Grade 12 / Limit of sequences 62 exercises (100% corrected)

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1. Reminders: arithmetic and geometric sequences E.3393 Consider the arithmetic sequence u n n N of first term 3 4 and reason 1 2 . 1 Determine the value of the first five terms of this se-quence. 2 Give the explicit formula of u n giving the value of a term as a function of its rank. 3 Determine the value of the following sequence : S = u 5 + u 6 + · · · + u 12 E.3394 Consider the geometric sequence u n n N of first term 16 27 and reason 3 2 . 1 Determine the value of the first five terms of this se-quence. 2 Give the explicit formula of u n giving the value of a term as a function of its rank. 3 Determine the value of the following sequence : S = u 3 + u 4 + · · · + u 16 E.5012 1 Let u n be an arithmetic sequence defined for n N . We have the value of the following two terms : u 4 = 3 ; u 7 = 15 a Determine the characteristic elements of the suite u n . b Give the recurrence formula, then the explicit formula for the sequence u n 2 Let v n be a geometric sequence defined for n N . We have the value of the following two terms : v 2 = 2 ; v 5 = 54 a Determine the characteristic elements of the suite v n . b Give the recurrence formula, then the explicit formula for the sequence v n E.6724 Consider the two sequences of numbers below, whose first seven terms are given : a 3 ; 5 ; 7 ; 10 ; 12 ; 14 ; 16 b 6 ; 3.5 ; 1 ; -1.5 ; -4 ; -6.5 ; -9 For each of the questions, can we conjecture that the sequence is an arithmetic sequence? If yes, give the first term and the reason. If no, justify your rejection of this statement. E.6725 Consider the two sequences of numbers below given the first six terms : a 8 ; 4 ; 2 ; 1 ; 1 2 ; 1 4 b 1 ; 3 ; 9 ; 18 ; 54 ; 162 For each of the questions, can we conjecture that the sequence is a geometric sequence? If so, specify the first term and the reason. If not, justify your rejection of the conjecture. E.3398 Identifying each of the sums as a sum of the terms of an arithmetic or geometric sequence, determine each of their values : a 12 + 7 + 2 + ( 3) + · · · + ( 28) b 27 + 3 + 1 3 + · · · + 1 243 c 2 3 + 8 3 + 14 3 + · · · + 62 3 d 1 2 4 + 1 2 6 + 1 2 8 + · · · + 1 2 24 E.3807 Consider the sequence p n n N whose first six terms verify: The first six terms are all positive and their sum is 1 . The first six terms of the sequence are non-constant. The first six terms of p n are consecutive terms of an arithmetic sequence. The numbers p 1 , p 2 , p 4 are three consecutive terms of a geometric sequence. Determine the value of the first six terms of the sequence ( p n ) . 2. Reminders: other E.3395 1 Consider the sequence u n n N defined by: u 0 = 1 u 1 = 1 u n +2 = u n +1 + u n pour tout n N Determine the value of the first eight terms of the se-quence u n . 2 Consider the sequence v n n N defined by: v 1 = 2 ; v n +1 = 1 v n + n for all n N Determine the first five terms of the sequence v n . E.3396 Determine the value of each of the fol-lowing sums : a 7 i =0 i b 8 i =3 i 2 i c 7 i =0 i 4 d 6 i =1 1 i e 4 i =1 1 i 2 f 3 =0 i =0 i https://chingmath.fr chapExoCorrec/3393 sacados/3393 chapExoCorrec/3394 sacados/3394 chapExoCorrec/5012 sacados/5012 chapExoCorrec/6724 sacados/6724 chapExoCorrec/6725 sacados/6725 chapExoCorrec/3398 sacados/3398 chapExoCorrec/3807 sacados/3807 chapExoCorrec/3395 sacados/3395 chapExoCorrec/3396 sacados/3396
E.5042 Justify that, in each question, the infor-mation below does not define sequences : a u 0 = 5 ; u n +1 = 2 · u n 3 for all n N b u 0 = 1 ; u 1 = 4 ; u n +1 = u n 3 for all n N c u 0 = 3 ; u n = 2 · u n 1 2 for all n N d u 0 = 1 ; u n = u n 1 2 u n 1 + 1 for all n N 3. Limits of arithmetic and geometric sequences E.6726 1 Consider the sequence u n arithmetic with first term 4 and reason 5 : a Complete the table below : n 0 1 2 3 4 5 6 7 u n 4 1 6 11 16 21 b What conjecture can be made about the value of the term u n as the rank n becomes larger and larger? Note: lim n ↦→ + u n = : : : : : : 2 Consider the sequence v n arithmetic of first term 3 and reason 1.2 : a Complete the table below : n 0 1 2 3 4 5 6 7 v n 3 1.8 0.6 0.6 1.8 3 b What conjecture can be made about the value of the term v n as the rank n becomes larger and larger? Note: lim n ↦→ + v n = : : : : : : E.6727 1 Consider the sequence u n geometric with first term 4 and reason 2 : a Complete the table below : n 0 1 2 3 4 5 6 7 u n 4 8 16 32 64 128 b What conjecture can be made about the value of the term u n as the rank n becomes larger and larger? Note: lim n ↦→ + u n = : : : : : : 2 Consider the sequence v n geometric with first term 81 and reason 1 3 : a Complete the table below : n 0 1 2 3 4 5 6 7 v n 81 27 9 3 1 1 3 b What conjecture can be made about the value of the term v n as the rank n becomes larger and larger? Note: lim n ↦→ + v n = : : : : : : E.6728 Consider the sequence u n geometric with first term 2.8 and reason 0.9 . 1 Using the calculator, complete the table below using val-ues approximated to the hundredth : n 0 1 2 3 4 5 6 7 u n 2.8 2.52 2.268 2.041 2 Using the calculator, what conjecture can be made for the limit of the terms in the sequence u n ? We note : lim n ↦→ + u n = : : : E.2557 1 Consider the sequence u n n N defined explicitly by: u n = 9 n 5 a Determine the nature of the sequence u n , specifying its characteristics. b Determine the limit of the sequence u n . 2 Consider the sequence v n n N defined explicitly by: v n = 2 · 1 3 n a Determine the nature of the sequence v n , specifying its characteristics. b Determine the limit of the sequence v n . E.6729 Give, if possible, the limits of the follow-ing sequences : 1 The sequence u n is geometric with strictly negative first term and reason 2 . 2 The sequence v n is geometric with strictly positive first term and reason 3 . 3 The suite w n is geometric with strictly negative first term and reason 0.2 . 4. Sum limits of terms of sequences E.2559 1 Let u n n N be the arithmetic sequence of first term 2 and reason 1 . a Determine the explicit expression of the terms of the sequence as a function of rank n . b Note S n = u 0 + u 1 + ··· + u n the sum of the first ( n +1) terms of the sequence. Give the expression of S n as a https://chingmath.fr chapExoCorrec/5042 sacados/5042 chapExoCorrec/6726 sacados/6726 chapExoCorrec/6727 sacados/6727 chapExoCorrec/6728 sacados/6728 chapExoCorrec/2557 sacados/2557 chapExoCorrec/6729 sacados/6729 chapExoCorrec/2559 sacados/2559
function of n . c Deduce the limit: lim n ↦→ + S n . 2 Let v n n N be the geometric sequence of first term 5 and reason 1 2 . a Determine the explicit expression of the terms of the sequence as a function of rank n . b Note S n = v 0 + v 1 + ··· + v n the sum of the first ( n +1) terms of the sequence. Give the expression of S n as a function of n . c Deduce the limit: lim n ↦→ + S n . E.2588 Let u n n N be a geometric sequence of first term 2 and reason 2 5 : 1 Determine the first three terms of this sequence. 2 a Determine the expression of the sum of the first n +1 terms of this sequence as a function of n . b Deduce the value of the following limit: lim n ↦→ + u 0 + u 1 + · · · + u n E.2622 Consider the sequence u n n N geomet-ric with first term 4 × 5 2 and reason 1 5 and sum S n defined by: S n = u 3 + u 4 + · · · + u n for any n 5 1 Determine the expression of S n as a function of n . 2 Justify that the sequence S n converges to 1. E.2621 Consider the sequence u n n N geomet-ric of first term 1 and reason 1 2 and the sequence ( R n ) defined, for n 2 , by the sum : R n = u n + u n +1 + · · · + u 2 n Determine the limit of the sequence ( R n ) . E.3105 Determine and justify the limits of the following amounts : a S = 1 2 + 1 2 2 + 1 2 3 + · · · + 1 2 n b S = 15 4 +5 × 3 4 2 5 × 3 4 3 +5 × 3 4 4 + ··· +5 × 3 4 n E.6174 A runner sets himself a challenge : he wants to circumnavigate Europe. On the first day, he covers 50 km . Through fatigue, from day to day, his daily distance travelled is reduced by 1 % . We note u n the length covered by the runner on the n -th day. Assuming that the runner continues his run indefinitely, we obtain a sequence u n defined for any non-zero natural number. 1 Determine the value of the first four terms of the se-quence u n . 2 a What is the nature of the sequence u n ? Give the characteristic elements of the sequence u n . b Express the term u n as a function of rank n . c What distance will the runner cover on 100 e day? We’ll round the value to the tenth of a kilometer. 3 Note S the sum of the first n terms of the sequence u n : S n = u 1 + u 2 + · · · + u n a Express the sum S n as a function of rank n . b Complete the following table, rounding values to the nearest tenth of a kilometer: n 10 100 500 750 1000 S n c What conjecture can be made about the limit of the sum S n when the value of n becomes larger and larger? E.2560 A globetrotter has bet to cover 5 000 km on foot. He can, fresh and ready, cover 50 km in a day, but every day fatigue builds up and so his performance decreases by 1 % every day. We’ll note d n the distance covered during the n -th day. 1 Calculate the distances d 1 , d 2 , d 3 covered during the first three days. 2 What precisely is the nature of the sequence? Determine the value of d n as a function of n . 3 Note L n the distance in kilometers traveled after n days. L n = d 1 + d 2 + · · · + d n a Determine the expression of L n as a function of n . b Deduce the limit of L n when n tends towards + . Can the globetrotter win? c Using the calculator, determine the minimum number of days N it would take him to travel 4 999 km E.5738 Consider the sequence u n de-fined on N by: u 0 = 2 ; u n = 2 × 2 3 n + n For any non-zero natural number n , we pose : S n = n k =0 u k = u 0 + · · · + u n ; T n = S n n 2 1 Express the term S n in terms of n . 2 Determine the limit of the sequence T n . 5. Other limits E.3397 Consider the function f defined on [ 4 ; 4] whose representative curve C f is given below : https://chingmath.fr chapExoCorrec/2588 sacados/2588 chapExoCorrec/2622 sacados/2622 chapExoCorrec/2621 sacados/2621 chapExoCorrec/3105 sacados/3105 chapExoCorrec/6174 sacados/6174 chapExoCorrec/2560 sacados/2560 extrait de Polynesie - 2006 - Obligatoire - 4 points chapExoCorrec/5738 sacados/5738 chapExoCorrec/3397 sacados/3397
-4-3-2-1234I-4-3-2-123JOCf 23I2JO(d -3-2-123456I23456JOCf Consider the sequence u n n N defined by the relation: u 0 = 2 ; u n +1 = f u n 1 Show that the term u 1 is equal to 3 . 2 Justify the following equalities: a u 2 = 0.5 b u 3 = 2.5 3 Complete the following table : n 0 1 2 3 4 5 6 7 8 9 u n 4 What can be said about the limit of the terms of the sequence u n ? E.3411 Consider the sequence u n n N defined by the recurrence relation: u 0 = 5 2 ; u n +1 = 1 2 · u n + 3 2 for any n N The graph below represents, in a reference frame O ; I ; J orthonormal, the straight line ( d ) having equation : y = 1 2 · x + 3 2 1 Graphically, on the x-axis represented the first five terms of this sequence (constructions must be left) . 2 a Using a calculator, complete the table below, giving values approximated to the nearest tenth : n 0 1 2 3 4 5 6 7 8 9 u n 2.5 0.25 1.38 0.81 1.09 b What conjecture can be made about the limit of the sequence u n ? E.3412 Consider the sequence u n n N defined by the recurrence relation: u 0 = 1 ; u n +1 = f u n for all n N where the function f is defined by: f ( x )= x 2 +7 · x +14 2 · x +3 The graph below represents, in an orthonormal coordinate system O ; I ; J , the curve C f representing the function f . 1 Graphically represent the first five terms of this sequence on the x-axis (the constructions must be left) . 2 a Using a calculator, complete the table below by indi-cating the values of the terms rounded to two decimal places. n 0 1 2 3 4 5 u n 1 2 3 ; 2 3 ; 76 4 ; 03 n 6 7 8 9 10 11 u n b What conjecture can be made about the limit of the terms of the sequence u n ? 6. With a spreadsheet https://chingmath.fr -4-3-2-1234I-4-3-2-123JOCf chapExoCorrec/3411 sacados/3411 23I2JO(d chapExoCorrec/3412 sacados/3412 -3-2-123456I23456JOCf
123456ABCDExnynwntn1128,339,258,949,029,009,009,009,00 1234567ABxnyn-34-4,81,4-4,681,76-2,688-4,2160,3792-4,98563,29472-3,76096 E.6732 Use the calculator to complete the ta-ble of values for each of the following sequences. If necessary, round the values to the nearest hundredth : 1 Let u n be defined by the relation: u n = 2 · n + 3 for any n N n 0 1 2 3 4 5 6 7 u n 2 Let v n be defined by the relation: v 0 = 5 ; v n +1 = 0.75 · v n + 3 for any n N Let w n be defined by the relation: w n = v n 12 for any n N a Complete the table of values : n 0 1 2 3 4 5 6 7 v n w n b Verify that the 8 terms of the sequence w n allow us to conjecture that the sequence w n is geometric. 3 Let t n be defined by the relationship : t 0 =0 ; t 1 =1 ; t n +1 = t n + t n 1 for all n N n 0 1 2 3 4 5 6 7 t n 4 Let a n and b n be defined by the relations : a 0 =2 b 0 = 1 ; a n +1 =2 · a n b n b n +1 = a n +3 · b n for any n N n 0 1 2 3 4 5 6 7 a n b n E.6731 We define the two sequences u and v by: u 0 = 1 v 0 = 12 ; u n +1 = 1 3 · u n +2 · v n v n +1 = 1 4 · u n +3 · v n for any n N 1 Using a spreadsheet, generate the first 20 terms of these two sequences to obtain a table sim-ilar to the one shown opposite. 2 We define the sequence w n by: w n = v n u n a In the column C , express the first 20 terms of the sequence w . b What can be done to demonstrate that the sequence w follows a geometric progression over its first 20 terms? 2 We define the sequence t defined by: t n =3 · u n +8 · v n a Express the first 20 terms of the sequence t . b What conjecture can be made about the nature of the sequence t ? E.6722 Consider the two sequences x n and y n jointly defined by the relations : x 0 = 3 y 0 = 4 et x n +1 = 0.8 · x n 0.6 · y n y n +1 = 0.6 · x n + 0.8 · y n for all n N 1 Using a spreadsheet, generate the first 100 terms of the sequence in a table similar to the one shown oppo-site. 2 Use the graphics tool, selecting the range A2:B101 to represent in the plane the points M n defined by M n ( x n ; y n ) . The representation mode ˇ XY (dis-persion) ı will be chosen. 3 a What conjecture can be made about the position of the sequence of points M n in the plane? b Verify that the point M 0 verifies this conjecture. c Establish the relationship : OM n +1 = OM n d Complete the following sentence : ˇ If, for any natural number, the terms of a se-quence verify the relation u n +1 = u n then the se-quence is . . . . . . . . . ı 7. Arithmetic-geometric sequences E.6733 Consider the sequence u n defined by the relation: u 0 = 8 ; u n +1 = 0.95 · u n + 0.5 for any n N 1 We define the sequence v n defined by the relation: v n = u n 10 for all n N a Justify that the sequence v n is a geometric sequence of reason 0.95 . Specify the value of its first term. b Express the terms of the sequence v n as a function of n . 2 Deduce an expression for the sequence u n as a function of n 3 Determine the limit of the terms of the sequence u n when n tends to + . https://chingmath.fr chapExoCorrec/6732 sacados/6732 chapExoCorrec/6731 sacados/6731 123456ABCDExnynwntn1128,339,258,949,029,009,009,009,00 chapExoCorrec/6722 sacados/6722 1234567ABxnyn-34-4,81,4-4,681,76-2,688-4,2160,3792-4,98563,29472-3,76096 chapExoCorrec/6733 sacados/6733
E.6734 Consider the sequence u n defined by the relation: u 0 = 2 ; u n +1 = 2 · u n + 0.5 for any n N 1 We define the sequence v n defined by the relation: v n = u n + 0.5 for all n N a Justify that the sequence v n is a geometric sequence whose characteristic elements will be specified b Express the terms of the sequence v n as a function of n . 2 Deduce an expression for the sequence u n as a function of n 3 Determine the limit of the terms of the sequence u n when n tends to + . E.3399 We wish to study the sequence ( u n ) of first term u 0 =5 defined by the following recurrence relation: u n +1 = 1 3 u n + 4 for all n N We define the sequence v n by: v n = u n 6 for all n N 1 Show that the sequence ( v n ) is a geometric sequence whose first term and reason will be specified. 2 Express v n as a function of rank n . 3 Deduce the expression of u n as a function of n . 4 Deduce the limit of the sequence u n . E.5740 Consider the sequence u n ) de-fined on N by: u 1 = 0 ; u n +1 = 0.2 · u n + 0.04 for all n N We admit that for any natural number: u n < 0.05 We define the sequence v n on N by the relation: v n = u n 0.05 1 Show that the sequence v n is a geometric sequence whose reason will be specified. 2 Determine the expression of the terms of the sequence v n as a function of n . Deduce the expression of the terms of the sequence u n as a function of n . 3 Deduce the limit of the sequence u n . 8. Jointly defined sequences E.6739 Consider the two sequences u n and v n jointly defined by the following relationships : u 0 = 5 v 0 = 4 ; u n +1 = 2 · u n v n v n +1 = 3 · u n + 4 · v n for any n N 1 Consider the sequence w n defined by the relation: w n = v n u n for all n N a Establish that the sequence w n is a geometric se-quence of reason 5 . b Deduce that, for any natural number n , the term of rank n is expressed as : w n = 5 n 2 Consider the sequence t n defined by: t n = 3 · u n + v n a Show that : t 0 =19 b Establish that for any natural number, we have equal-ity: t n +1 = t n for any n N We will admit that, for any n N , we have : t n =19 3 Deduce an expression for the terms of the sequences u n and v n as a function of n . 4 Deduce the limits of the sequences u n and v n . E.6738 Consider the two sequences u n and v n jointly defined by the following relations : u 0 = 3 v 0 = 1 ; u n +1 = 3 · u n 2 · v n v n +1 = u n + 2 · v n 1 Consider the sequence w n defined by the relation: w n = v n u n for all n N a Establish that the sequence w n is a geometric se-quence of reason 4 . b Deduce that, for any natural number n , the term of rank n is expressed as : w n = 4 × 4 n 2 Consider the sequence t n defined by: t n = 4 · u n + 8 · v n for any n N a Give the value of the term t 0 . b Establish that for any natural number, we have the equality: t n +1 = t n We’ll admit that the sequence t n is constant. 3 Deduce an expression for the terms of the sequences u n and v n as a function of n . 4 Deduce the limits of the sequences u n and v n . https://chingmath.fr chapExoCorrec/6734 sacados/6734 chapExoCorrec/3399 sacados/3399 chapExoCorrec/5740 sacados/5740 chapExoCorrec/6739 sacados/6739 chapExoCorrec/6738 sacados/6738
E.3414 Consider the two sequences p n n N and q n n N whose first terms are: p 0 =5 ; q 0 = 2 They are defined by the following recurrence relations : p n +1 = 0.5 · p n + 0.4 · q n ; q n +1 = 0.4 · p n + 0.5 · q n We define the sequences u n n N and v n n N by the follow-ing relations : u n = q n + p n ; v n = p n q n 1 Determine the exact value of the first three terms of each of the sequences u n and v n . 2 a Show that the sequence u n is a geometric sequence of reason 0.9 . b Deduce the limit of the sequence u n . 3 Determine the limit of the sequence v n . 4 a Noting that u n + v n =2 · p n , deduce that the sequence p n is convergent ; specify its limit. b Establish that the sequence q n is convergent ; deter-mine its limit. E.6759 Consider the sequences a n and b n defined by: a 0 = 6 b 0 = 1 a n +1 = 0.2 · a n + 1.3 · b n b n +1 = 0.8 · a n 0.2 · b n for any n N 1 Express the terms a n +2 and b n +2 in terms of a n and b n . 2 What can be said about the terms of the sequence a 2 n ? E.6758 Consider the sequences a n and b n defined by: a 0 = 2 b 0 = 1 ; a n +1 = 0.8 · a n + 0.9 · b n b n +1 = 0.4 · a n 0.8 · b n n N 1 Establish the equalities: a n +2 = a n ; b n +2 = b n 2 What can we say about the limits of the sequences a n and b n ? 9. Other suites E.6765 Let u n be the sequence defined by its first term u 0 =5 and, for any natural number n by: u n +1 = 0.5 · u n + 0.5 · n 1.5 1 Let v n be the sequence defined for any natural number n by: v n = 0.1 · u n 0.1 · n + 0.5 Show that the sequence v n is geometric of reason 0.5 and then express v n as a function of n . 2 Deduce that, for any natural number n : u n = 10 × 0.5 n + n 5 3 Then determine the limit of the sequence u n E.6799 Consider the sequence u n defined by: u 0 = 6 ; u n +1 = 2 · u n 3 · n + 5 for all n N 1 Give the first three terms of the sequence u n . 2 Consider the sequence v n defined by: v n = u n 3 · n + 2 a Demonstrate that the sequence v n is a geometric se-quence of reason 2 . b Deduce an expression for the terms of the sequence v n as a function of their rank. 3 a Justify that for any natural number n , we have : u n = 8 × 2 n + 3 · n 2 b Deduce the limit of suite u n . E.5737 Let the numerical sequence u n be defined on N by: u 0 = 2 ; u n +1 = 2 3 · u n + 1 3 · n + 1 for all n N We denote by v n the sequence defined on N by: v n = u n n 1 Demonstrate that the sequence v n is a geometric se-quence of reason 2 3 . 2 Deduce that for any natural number n : u n = 2 · 2 3 n + n 3 Determine the limit of the sequence u n . E.2620 Consider the sequence u n n N whose first term is 0 defined by the following recurrence relation: u n +1 = 2 5 · u n 3 · n 8 pour tout n N 1 Determine the first three terms of this sequence. 2 Consider the sequence v n n N defined by the relation: v n = u n + 5 n + 5 for all n N a Show that the sequence v n is a geometric sequence whose reason and first term will be specified. b Deduce the explicit formula for the sequence u n of a term as a function of n its rank. 3 Deduce the limit of the sequence u n . https://chingmath.fr chapExoCorrec/3414 sacados/3414 chapExoCorrec/6759 sacados/6759 chapExoCorrec/6758 sacados/6758 chapExoCorrec/6765 sacados/6765 chapExoCorrec/6799 sacados/6799 chapExoCorrec/5737 sacados/5737 chapExoCorrec/2620 sacados/2620
E.3285 We define the sequence u n is defined by: u 0 = 1 ; u n +1 = 1 2 u n + n 1 for all n N We define the sequence ( v n ) by: v n =4 u n 8 n +24 1 By successive transformation, establish the following equality: v n +1 = 1 2 · v n . 2 Deduce an expression for the terms of the sequence u n as a function of n . E.3518 Consider the numerical sequence u defined by: u 0 = 1 ; u n +1 = 1 3 · u n + n 1 for any natural number n . Let v be the sequence defined for any integer ntaturel, by: v n = 4 · u n 6 n + 15 1 Show that v is a geometric sequence. 2 Calculate v 0 , then calculate v n as a function of n . Deduce that for any natural number n : u n = 19 4 × 1 3 n + 6 n 15 4 3 Show that the sequence u can be written as : u = t + w t is a geometric sequence w a sequence arithmétique 4 Calculate the value of the two sums : T n = t 0 + t 1 + · · · + t n ; W n = w 0 + w 1 + · · · + w n . Deduct : U n = u 0 + u 1 + ··· + u n . 10. Other sequences: linear recurrent sequences of order 2 E.3515 Consider the sequence u n n N defined by: u 0 = 0 u 1 = 1 ; u n +1 = 7 · u n + 8 · u n 1 pour tout n N 1 Determine the value of the first five terms of the sequence u n . 2 Show that the sequence s n n N defined by: s n = u n +1 + u n pour tout n N is a geometric sequence whose reason will be specified. Deduce s n as a function of n . 3 a We pose v n =( 1) n · u n and consider the sequence t n n N defined by: t n = v n +1 v n for all n N Express t n as a function of s n . b What is the nature of the sequence t n . 4 a Express v n , then u n , as a function of n (we can cal-culate, in two ways, the sum t 0 + ··· + t n 1 ) . b Determine : lim n ↦→ + u n 8 n . E.3421 Consider the set ( E ) of the se- quences x n defined on N and verifying the following rela-tion : for any non-zero natural number n , x n +1 x n =0.24 · x n 1 1 Consider a non-zero real and define on N the sequence t n by t n = n . Show that the sequence t n belongs to the set ( E ) if, and only if, is a solution of the equation : 2 0.24 = 0 Deduce the sequences t n belonging to the set ( E ) . Let ( E ) be the set of sequences u n defined on N by a rela-tion of the form : u n = ¸ · (1.2) n + ˛ · ( 0.2) n ¸ and ˛ are real numbers. 2 Consider a sequence u n of the set ( E ) . Determine the values of ¸ and ˛ such that : u 0 = 6 and u 1 = 6.6 Deduce that, for any natural number n : u n = 39 7 · (1.2) n + 3 7 · ( 0.2) n . 3 Determine : lim n ↦→ + u n . 11. Limits of explicitly defined sequences E.2558 Determine the limits of the sequences u n defined below : a n 3 × 5 n b n 2 7 n c 1 3 n 3 2 n d 8 n 3 n e 5 n 2 n 3 n + 2 n f 31 7 n · 2 8 n E.3104 In each case, determine the limit of the sequence u n whose general term as a function of n is given below a n 5 × 3 n 2 3 b 5 n 8 n c 2 3 n · 4 3 n +2 d 3 n 2 n 5 n 4 n 12. Gendarme theorems https://chingmath.fr chapExoCorrec/3285 sacados/3285 chapExoCorrec/3518 sacados/3518 chapExoCorrec/3515 sacados/3515 chapExoCorrec/3421 sacados/3421 chapExoCorrec/2558 sacados/2558 chapExoCorrec/3104 sacados/3104
E.2554 Consider the sequence u n n N de-fined, for any natural number n , by the explicit relation: u n = 3 n +( 1) n 2 n 1 1 Determine the first three terms of the sequence u n . 2 Establish the following frame : For any n N : 3 n 1 2 n 1 u n 3 n +1 2 n 1 3 Deduce the convergence value of u n . E.2567 Let u n n N be defined by the explicit formula of its rank term n : u n = 2 · n + 1 2 · n 1 Show the following equality for any n N : u n = 1 2 · n + 1 + 2 · n 2 For any non-zero natural number n , establish the follow-ing frame : 0 <u n < 1 2 · 2 · n 3 Deduce the limit of the sequence u n . E.3441 Consider the sequence u n n N whose rank term n is defined by the relation: u n = 1 n + 1 + 1 n + 2 + · · · + 1 n + n 1 Establish the following frame for any non-zero natural number n : n n + n u n n n + 1 2 Deduce the convergence of the sequence u n ; specify the value of the limit. E.2587 Consider the sequence u n n N is de-fined explicitly by the formula : u n = 3 4 n 2 + 1 + 3 4 n 2 + 2 + · · · + 3 4 n 2 + n 1 Compare the following two terms : 3 4 n 2 + 1 and 3 4 n 2 + n 2 Establish that the sequence u n converges to 3 2 . 13. Lesson - Sequences E.5741 Let be a real number. Consider a se-quence u n that converges to then the real to which the sequence u n converges is unique. E.3281 Prerequisite : definition of a se-quence tending to + . ˇA sequence tends to + if, for any real A , all the terms of the sequence are, from a certain rank, greater than A ı Prove the following theorem : a non-major increasing se-quence tends to + E.5496 Consider the two sequences u n and v n verifying: There exists n 0 such that from n 0 , the terms of the two sequences : n n 0 = v n u n lim n ↦→ + u n = + Establish that : lim n ↦→ + v n = + E.5497 Consider a growing sequence u n . If the sequence u n converges to a finite limit then all terms of the sequence u n are less than or equal to . 14. Unclassified financial years E.5570 Consider the numerical sequence v n defined for any natural number n by: v 0 = 1 ; v n +1 = 9 6 v n for any integer n N Consider the sequence w n defined by: w n = 1 v n 3 for any natural number n . 1 Demonstrate that w n is an arithmetic sequence of rea-son 1 3 and first term 1 2 2 a Determine the expression of the terms of the se-quence w n as a function of rank n . b Deduce the expression of the terms of the sequence v n as a function of rank n . (we will not simplify the expression of v n ) . 3 Determine the limit of the sequence v n . E.4012 Consider the sequence of real num-bers u n defined on N by: u 0 = 1 ; u 1 = 1 2 ; u n +2 = u n +1 1 4 · u n for all n N 1 Calculate u 2 and deduce that the sequence u n is nei-ther arithmetic nor geometric. 2 We define the sequence v n by posing : v n = u n +1 1 2 · u n for all n N a Calculate v 0 . b Establish that v n is geometric of reason 1 2 . c Express v n in terms of n . https://chingmath.fr chapExoCorrec/2554 sacados/2554 chapExoCorrec/2567 sacados/2567 chapExoCorrec/3441 sacados/3441 chapExoCorrec/2587 sacados/2587 chapExoCorrec/5741 sacados/5741 chapExoCorrec/3281 sacados/3281 chapExoCorrec/5496 sacados/5496 chapExoCorrec/5497 sacados/5497 chapExoCorrec/5570 sacados/5570 Extrait Liban 2013 chapExoCorrec/4012 sacados/4012 Extrait Antilles-Guyane Septembre 2010
E.4225 Peter and Claude play tennis. Both players have the same chance of winning the first game. Thereafter, when Peter wins a game, the probability that he wins the next is 0.7 . And if he loses one game, the probability that he will lose the next is 0.8 . Throughout the exercise, n is a non-zero natural number. Consider the events : G n : ˇ Pierre wins the n -game. ı P n : ˇ Pierre loses the n -th game. ı We pose : p n = P ( G n ) ; q n = P ( P n ) Finding a recurrence relation : 1 Determine p 1 then the conditional probabilities : P G 1 ( G 2 ) ; P P 1 ( G 2 ) . 2 Justify the equality: p n + q n =1 . 3 Demonstrate that for any non-zero natural number n : p n +1 = 0.5 · p n + 0.2 . E.2555 Determine the limits of the sequences u n n N below defined explicitly: a u n = 2 n 2 3 n + 1 n + 1 b u n = n 3 n 2 + 1 c u n = 2 n + 1 n + 1 d u n = 1 + n 2 n 2 + 3 n 3 E.6176 Determine the value of the following limits: a lim n ↦→ + n 2 + 2 b lim n ↦→ + 2 + 1 n c lim n ↦→ + n 3 + n + 2 d lim n ↦→ + n 1 n e lim n ↦→ + n · n 10 f lim n ↦→ + 1 + 1 n n + 1 E.6177 Determine the value of the following limits: a lim n ↦→ + n 2 n b lim n ↦→ + n 2 + n + 1 n c lim n ↦→ + 1 n 2 + 1 n d lim n ↦→ + n n 2 + n + 1 e lim n ↦→ + 2 n 2 + n + 1 n 2 f lim n ↦→ + n 2 1 n https://chingmath.fr chapExoCorrec/4225 sacados/4225 Extrait d'Asie Juin 2006 chapExoCorrec/2555 sacados/2555 chapExoCorrec/6176 sacados/6176 chapExoCorrec/6177 sacados/6177