Outside the high school program / Matrix 19 exercises (100% corrected)

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1. Newton’s binomial formula E.5130 Consider the two matrices : I = 1 0 0 0 1 0 0 0 1 ; A = 0 2 5 0 0 2 0 0 0 1 Determine for any natural number, the expression of the powers I n and A n . 2 Deduce the expression of the matrix I + A 5 . E.5162 Consider the matrix A defined by: A = 1 2 3 0 1 3 0 0 1 The aim of this exercise is to give an expression for A n for any natural number n . 1 Consider the matrix B defined by B = A I 3 . Give the expression of B 2 and B 3 . 2 a Can we use Newton’s binomial formula to develop the expression I 3 + B n for n non-zero natural num-ber? Justify your answer. b Demonstrate that for any natural number n greater than or equal to 3 , we have : A n = n 0 · I 3 + n 1 · B + n 2 · B 2 E.5163 Consider the two matrices A and D de-fined by: A = 1 1 2 0 1 2 0 0 1 ; D = 1 0 0 0 1 0 0 0 1 The aim of this exercise is to give an expression for A n for any natural number n . 1 Consider the matrix B defined by B = A D . Give the expression of B 2 and B 3 . 2 a Can we use Newton’s binomial formula to develop the expression D + B n for n non-zero natural num-ber? Justify your answer. b Demonstrate that for any natural number n greater than or equal to 3 , we have : A n = ( 1) n · n 0 · I 3 + ( 1) n 1 · n 1 · B + ( 1) n 2 · n 2 · B 2 E.5131 Consider the matrix A defined by: A = 3 1 2 0 3 1 0 0 3 1 Write the matrix A in the form B + C where B is a square diagonal matrix. 2 a For any integer n , give the expression for C n . b Verify that the matrices B and C are commutative. c Establish the following equality for any integer n greater than or equal to 2: A n = B n + n · C · B n + n 2 · C 2 · B n 2 2. Newton’s binomial formula and sequences E.5164 Consider the A square matrix of dimen-sion 3 defined by: A = 2 0 3 0 1 0 0 0 2 1 Consider the sequence u n defined by: u 0 = 0 ; u n +1 = 2 · u n + 3 × 2 n for all n N Establish that for any integer n , we have : A n = 2 n 0 u n 0 1 0 0 0 2 n 2 Consider the two matrices D and S defined by: D = 2 0 0 0 1 0 0 0 2 ; S = 0 0 3 0 0 0 0 0 0 a Show that : D · S = S · D . b Show that for any k 2 , we have : S k =0 3 . c Using Newton’s binomial formula, determine the ex-pression of A n for any non-zero natural number. 3 Deduce the explicit formula for the sequence u n . 3. Matrices and complex numbers E.5447 Consider the square matrix A of order 2 defined by: A = 1 1 2 1 Consider the matrices P and Q defined by: P = 1 1 1 + i 1 i ; Q = 1 2 + 1 2 · i 1 2 · i 1 2 1 2 · i 1 2 · i https://chingmath.fr chapExoCorrec/5130 sacados/5130 chapExoCorrec/5162 sacados/5162 chapExoCorrec/5163 sacados/5163 chapExoCorrec/5131 sacados/5131 chapExoCorrec/5164 sacados/5164 chapExoCorrec/5447 sacados/5447
where i is the complex number verifying: i 2 = 1 . 1 Show that the matrices P and Q are inverses of each other. 2 Show that matrix P 1 · A · P is a diagonal matrix. We note D this diagonal matrix in the rest of the exercise. 3 a Establish, using reasoning by recurrence, the follow-ing relationship for any natural number n : A n = P · D n · P 1 b Justify that for any integer n , we have the relation A n +4 = A n 4. Diagonalizable matrix E.5161 Consider the matrices A and P defined by: A = 5 3 6 4 ; P = 1 1 1 2 1 Show that the matrix P is an invertible matrix and give the expression for the matrix P 1 . 2 a Establish the existence of a matrix D verifying the equality: A = P · D · P 1 b Using reasoning by recurrence, establish that for any natural number n , we have the equality: A n = P · D n · P 1 c Deduce, for any non-zero natural number n , the ex-pression for A n . E.5160 Consider the matrices A and P defined by: A = 4 3 2 1 ; P = 3 1 2 1 1 Show that the matrix P is an invertible matrix and give the expression of the matrix P 1 . 2 a Establish the following equality: A = P · 2 0 0 1 · P 1 b Deduce, for any non-zero natural number n , the ex-pression for A n . E.5158 Consider the matrix A defined by: A = 2 2 1 1 1 1 2 4 3 and the two matrices P and Q defined by: P = 1 3 2 1 1 1 2 1 0 ; Q = 1 2 1 2 4 1 3 7 2 1 Show that the matrices P and Q are two matrices that are inverses of each other. 2 We denote D the matrix defined by: I = 2 0 0 0 1 0 0 0 1 a Establish equality: A = P · D · Q b Establish, using reasoning by recurrence, that for any natural number n , we have : A n = P · D n · Q c Deduce, for any non-zero natural number n , the ex-pression of the matrix A n . E.5159 Consider the matrix A defined by: A = 2 1 3 7 4 9 1 1 2 and the two matrices P and Q defined by: P = 1 2 1 1 1 2 1 1 1 ; Q = 3 1 5 1 0 1 2 1 3 1 Show that the matrices P and Q are two matrices that are inverses of each other. 2 Establish the existence of a matrix D verifying the equal-ity: A = P · D · Q and admitting as expression : D = a 0 0 0 b 0 0 0 c where a , b , c are three real num-bers. 3 a Using reasoning by recurrence, establish that for any natural number n , we have the equality: A n = P · D n · Q b Deduce, for any non-zero natural number n , the ex-pression for the matrix A n . https://chingmath.fr chapExoCorrec/5161 sacados/5161 chapExoCorrec/5160 sacados/5160 chapExoCorrec/5158 sacados/5158 chapExoCorrec/5159 sacados/5159
E.5146 Consider the matrix A square of dimen-sion 3 defined by: A = 3 6 1 4 5 2 2 6 0 The aim of the exercise is to determine an expression for the matrix A n for any natural number n . To do this, consider the two square matrices P and Q : P = 1 3 2 0 2 1 2 3 2 ; Q = 1 0 1 2 2 1 4 3 2 1 Show that the matrices P and Q are two matrices that are inverses of each other. 2 Establish equality: A = P · 1 0 0 0 2 0 0 0 1 · Q Note D the matrix: D = 1 0 0 0 2 0 0 0 1 3 a Give the expression for the matrix D n where n is a natural number. b Establish for any natural number n , the equality: A n = P · D n · Q c Give the expression of A n as a function of n . E.5356 Consider the two matrices of dimensions 2 : A = 1 6 1 4 ; P = 3 2 1 1 1 a Justify that the matrix P is an invertible matrix. b Give the expression for the matrix P 1 inverse of the matrix P . 2 Determine the value of the reals ¸ and ˛ achieving the following equality: A = P · ¸ 0 0 ˛ · P 1 3 a Using reasoning by recurrence, establish the follow-ing equality for any natural number n : A n = P · ¸ n 0 0 ˛ n · P 1 b Give the expression of A n as a function of n . E.6099 Consider the two matrices : A = 4 1 2 1 ; P = 1 1 1 2 1 a Justify that the matrix P is invertible and give the expression for the inverse matrix of P . b Let’s note D = P 1 · A · P . Show that the matrix D is diagonal. 2 a Using reasoning by recurrence, show that for any natural number n , we have : A n = P · D n · P 1 b Give the expression of the matrix A n as a function of the non-zero natural number n . 5. Systems overview E.6118 At a coffee shop, here are two orders and their bill amounts : Invoice: 4.5 e . Invoice: 10.8 e In this café, what are the prices of a croissant and a coffee? E.6119 At a coffee shop, here are two orders and their bill amounts : Invoice: 11 e . Invoice: 14.3 e In this café, what are the prices of a croissant and a can? E.6120 At a cafe, here are two orders and their bill amounts : Invoice: 15.2 e . Invoice: 10 e What are the prices, in this café, for a coffee and a can? E.6121 1 Solve the following system using the linear combination method : ( S ) : 3 x + 2 y = 5 4 x + 3 y = 3 2 Solve the following system using the substitution method : ( T ) : 3 x + y = 16 8 x 5 y = 12 E.6122 Consider the system ( S ) of equations : x 3 y = 8 4 x + y = 7 Solve the system ( S ) . https://chingmath.fr chapExoCorrec/5146 sacados/5146 chapExoCorrec/5356 sacados/5356 chapExoCorrec/6099 sacados/6099 chapExoCorrec/6118 sacados/6118 chapExoCorrec/6119 sacados/6119 chapExoCorrec/6120 sacados/6120 chapExoCorrec/6121 sacados/6121 chapExoCorrec/6122 sacados/6122
6. Unclassified financial years E.5392 We consider an evolutionary process ad-mitting the following transition matrix: T = 7 10 3 10 1 5 1 5 1 We consider the matrix P définie by: P = 3 1 2 1 a Show that the matrix P est is an invertible matrix and determine the expression of its inverse matrix. b Determine the existence of a D diagonal matrix veri-fying the equality: T = P · D · P 1 . c Établir, à l’aide d’un raisonnement par récurrence, la relation suivante pour tout entier naturel n : T n = P · D n · P 1 . d Determine the expression of the matrix T n as a func-tion of the natural number n . 2 Consider the two sequences a n and b n with respec-tive first terms a 0 and b 0 and satisfying the relation: a n +1 b n +1 = T · a n b n a Using recursive reasoning, establish the following equality for all natural numbers n : a n b n = T n · a 0 b 0 b Determine an expression for the terms of these two sequences in terms of n , a 0 and b 0 . c Deduce the limit of these two sequences. https://chingmath.fr chapExoCorrec/5392 sacados/5392