Outside the high school program / Arithmetic 17 exercises (including 15 corrected)

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20euro2020s0021291386s0021291386 DividendeDiviseurReste64523241..............................×6452...3241...×............×............×............ 1. Euclidean division E.1718 We give the Euclidean division of 195 695 by 3 : 195695 = 65231 × 3 + 2 1 By studying the product (65231 × 3+2) × 2 , determine the Euclidean division of 195695 × 2 by 3. 2 Do the same for the Euclidean division of 195 695 × 3 by 3. 3 Complete the following table : n 1 2 3 4 5 6 7 Euclidean division of 195695 × n E.16 It is admitted that we obtain the même remainder by dividing an integer by 9 than by dividing the sum of its digits by 9. For example: 8753 = 972 × 9 + 5 the remainder is therefore 5. 8 + 7 + 5 + 3 = 23 = 2 × 9 + 5 the remainder is also 5. Euro banknotes feature an 11-digit code preceded by a letter. The letter is replaced by its place in the usual alphabet of 26 digits. This produces an integer with 12 or 13 digits, and we find the remainder of dividing this number by 9 . This re-mainder is the même for all genuine banknotes and is worth 8 . Example : Code : s 00 212 913 862 Rank in the alphabet of the letter s : 19 Number obtained : 1 900 212 913 862 Remainder for this banknote : 8 1 The code u 01 308 937 097 appears on a banknote. a Give the 13 -digit integer corresponding to this code. b Calculate the remainder of the division by 9 of the sum of the 13 digits of this integer. c What can we say about this banknote? 2 On a genuine banknote appears the code s 02 166 448 10 x , x for the last illegible digit. Show that x +42 is congruent to 8 modulo 9. Deduce x . 3 On another authentic banknote, the part of the code formed by the 11 digits is 16 122 340 242 , but the letter preceding them has been erased. We call n the position of the erased letter in the alphabet. a Determine the possible values of n . b What are the possibilities for the erased letter?? 2. Pgcd with the Euclidean algorithm E.13 To make the fraction 6452 3241 irreducible, we will calculate the PGCD of the integers 6452 and 3241? https://chingmath.fr sacados/1718 chapExoCorrec/16 sacados/16 20euro2020s0021291386s0021291386 chapExoCorrec/13 sacados/13 DividendeDiviseurReste64523241..............................×6452...3241...×............×............×............
DividendeDiviseurReste24036.....................×240...36...×............×............ DividendeDiviseurReste410246.....................×410...246...×............×............ E.14 In a newly built house, we want to tile the floors in certain rooms. 1 The dining room floor is a rectangle of length 4.54 m and width 3.75 m . We want to tile this room with square tiles 33 cm square. We start the installation with a ˇ corner ı of the room as suggested in the adjacent figure. Calculate the number of uncut tiles that will have been laid. 2 The kitchen floor is a rectangle of length 4.55 m and width 3.85 m . We want to tile this room with a whole number of square tiles, without any cutting. a Give the list of divisors of 455 and then the list of divisors of 385. b Give the list of divisors common to 455 and 385. c What is then the largest possible side of the square tiles to be used to tile this kitchen? 3 We have rectangular tiles of length 24 cm and width 15 cm . a Give the list of multiples of 24 less than 400, then the list of multiples of 15 less than 400 b Give the list of multiples common to 24 and 15, less than 400. c What would be the side length of the smallest square room that could be tiled with an integer number of such tiles, without any cutting? E.3328 1 Using Euclid’s algorithm, complete the table below to determine the PGCD of the numbers 240 and 36 : 2 Make the fraction 240 36 irreducible by performing a sin- gle simplification. By what integer have you simplified? Justify your approach. E.4995 1 Using Euclid’s algorithm, determine the PGCD of the integers 410 and 246 : 2 a Simplify the fraction 246 410 . b Perform the following calculations : 246 410 8 5 ; 1 246 1 410 E.3329 1 Calculate the Greatest Common Divisor (PGCD) of 496 and 806. 2 Write 496 806 as an irreducible fraction. 3 Calculate 496 806 3 26 (we’ll give the result as an irreducible fraction) E.3749 Using Euclid’s algorithm, determine the PGCD of the integers a and b : a a = 354 ; b = 20 b a = 1 456 ; b = 256 c a = 17 ; b = 3941 d a = 256 419 ; b = 3 866 E.6077 Consider the equation ( E ) : 44 · x + 35 · y = 2 x N ; y N 1 a Using Euclid’s algorithm, show that the integers 44 and 35 are prime to each other. b Determine a pair ( x 0 ; y 0 ) verifying the relation: 44 · x 0 + 35 · y 0 = 1 2 Deduce the set of solutions to the equation ( E ) . 3. Integers, PGCD, PPCM E.259 1 Give the product decomposition of prime factors of the following natural integers : a 25 × 72 b 54 × 12 c 32 × 84 d 100 × 98 2 From question 1 , determine : a The PGCD of the pair (25 × 72 ; 54 × 12) ; b The PPCM of the pair (32 × 84 ; 100 × 98) of natural in- tegers. 3 Use a divisor tree to determine the set of divisors of the integer 315. E.277 1 Determine the decompositions into prime factors of the following integers : A 36 × 54 b 125 × 134 c 280 × 24 2 Deduce the PGCD and PPCM of the pair (6720 ; 16750) of natural numbers. https://chingmath.fr chapExoCorrec/14 sacados/14 chapExoCorrec/3328 sacados/3328 DividendeDiviseurReste24036.....................×240...36...×............×............ chapExoCorrec/4995 sacados/4995 DividendeDiviseurReste410246.....................×410...246...×............×............ chapExoCorrec/3329 sacados/3329 chapExoCorrec/3749 sacados/3749 chapExoCorrec/6077 sacados/6077 chapExoCorrec/259 sacados/259 chapExoCorrec/277 sacados/277
4. Unlimited development E.1822 Consider the geometric sequence ( u n ) with first term u 0 =2 and reason 3. 1 a Determine the terms u 1 , u 2 , u 3 and u 4 . b Give the base 7 writing of u 2 . c Show that writing in base 7 is 105 7 . d To obtain the base 7 writing of u 4 , a student has per-formed the multiplication below. Say whether or not he is right and explain why. 1 0 5 × 3 3 1 5 2 a Show that : u 5 =486 . b Consider the function f , taken from an algorithm, and taking as argument a a natural number: Function f(a) L empty list x a As long as x>0 r remainder of the division euclidean division of x by 7 Add r at the top of the list L x q End While Return L Complete the tablebelow to record the different val-ues taken by the variables of function f when calling function function f using parameter a =486 : r q L x Initialisation vide 486 End of stage 1 End of stage 2 . . . . . . Explain the link between the items in the list L and the writing of u 5 in base 7. 3 We divide the term u 10 of the sequence ( u n ) by some in-teger. We obtain the quotient Q whose decimal writing is Q =14.727 272 727 272 72 ::: writing in which the digits 7 and 2 repeat to infinity. Let ( v n ) be the geometric sequence of first term 0.72 and reason 0.01 . a Calculate v 0 + v 1 + v 2 b We pose S n = v 0 + v 1 + v 2 + ··· + c n where n is a non-zero natural number. c Calculate S n . Deduce lim n ↦→ + S n . d Deduce a writing of 0.727 272 : : : where the digits 7 and 2 repeat to infinity in the form of the quotient of two integers. What is the number by which we divided u 10 ? 5. Bezout’s theorem and Euclid’s algorithm E.3751 For each equation, determine a pair of integer solutions ( u ; v ) : a 354 · u + 49 · v = 1 b 34 · u + 57 · v = 1 E.3753 1 Determine a couple ( x ; y ) of integers solutions of the equation : 56 · x + 45 · y = 1 2 Deduce a couple ( x ; y ) ’of relative integers verifying the equality: 56 · x + 45 · y = 3 6. Unclassified financial years E.29 1 Without the calculator, perform the Euclidean division of 372 by 15 . 2 With the calculator, determine the Euclidean division of 37 852 by 23 . 3 a 2456 = 17 × 143 + 25 Deduce the Euclidean division of 2 456 by 17 . b 32 247 143 = 225 + 72 143 Deduce the Euclidean division of 32 247 by 143 . c 516 43 = 12 Deduce the Euclidean division of 516 by 43 . d 674 24 = 28 + 1 12 Deduce the Euclidean division of 674 by 24 . e 5460 63 = 86 + 2 3 Deduce the Euclidean division of 5 460 by 63 . https://chingmath.fr sacados/1822 chapExoCorrec/3751 sacados/3751 chapExoCorrec/3753 sacados/3753 chapExoCorrec/29 sacados/29
E.336 We want to determine the sign of the following expressions : 2 y ; x + y ; x y ; x (2 y 1) ; x + y In the following cases : x> 0 and y> 0 : Positive Négatif On ne peut conclude 2 y x + y x y x (2 y 1) x + y x> 0 and y< 0 : Positive Négatif On ne peut conclude 2 y x + y x y x (2 y 1) x + y E.5302 The aim of this exercise is to prove by absurdity that there are infinitely many prime integers of the form 4 n 1 , where n is an element of N (set of non-zero nat-ural numbers) . 1 Let E be the set of prime integers of the form 4 n 1 where n is an element of N . Show that E has at least two elements. 2 Assume E finite . Let P be the product of all elements of E and X =4 P 1 . a Find a minorant of X . b Show that X is not divisible by 2 , and deduce that any prime factor of X is either of the form 4 n +1 , or of the form 4 n 1 where n is an element of N . c Show that X has at least one prime factor of the form 4 n 1 where n is an element of N . 3 Considering a prime factor p of X of the form 4 n 1 , the definition of P and the relation X =4 P 1 , complete the demonstration by the absurd. https://chingmath.fr chapExoCorrec/336 sacados/336 chapExoCorrec/5302 sacados/5302