Problem 1PP: Since vectors in n may be regarded as n 1 matrices, the properties of transposes in Theorem 3 apply... Problem 2PP: Let A be a 4 4 matrix and let x be a vector in 4. What is the fastest way to compute A2x? Count the... Problem 3PP: Suppose A is an m n matrix, all of whose rows are identical. Suppose B is an n p matrix, all of... Problem 1E: In Exercises 1 and 2, compute each matrix sum or product if it is defined. If an expression is... Problem 2E: In Exercises 1 and 2, compute each matrix sum or product if it is defined. If an expression is... Problem 3E: In the rest of this exercise set and in those to follow, you should assume that each matrix... Problem 4E: Compute A 5I3 and (5I3)A, when A=[913876418]. Problem 5E: In Exercises 5 and 6, compute die product AB in two ways: (a) by the definition, where Ab1 and Ab2... Problem 6E: In Exercises 5 and 6, compute die product AB in two ways: (a) by the definition, where Ab1 and Ab2... Problem 7E: If a matrix A is 5 3 and the product AB is 5 7, what is the size of B? Problem 8E: How many rows does B have if BC is a 3 4 matrix? Problem 9E: Let A=[2531] and B=[453k]. What value(s) of k, if any, will make AB = BA? Problem 10E: Let A=[2346], B=[8455], and C=[5231]. Verify that AB = AC and yet B C. Problem 11E: Let A=[111123145] and D=[200030005]. Compute AD and DA. Explain how the columns or rows of A change... Problem 12E: Let A=[3612]. Construct a 2 2 matrix B such that AB is the zero matrix. Use two different nonzero... Problem 13E: Let r1,..., rp be vectors in n, and let Q be an m n matrix. Write the matrix [Qr1 Qrp] as a product... Problem 14E: Let U be the 3 2 cost matrix described in Example 6 of Section 1.8. The first column of U lists the... Problem 15E: Exercises 15 and 16 concern arbitrary matrices A, B, and C for which the indicated sums and products... Problem 16E: a. If A and B are 3 3 and B = [b1 b2 b3], then AB = [Ab1 + Ab2 + Ab3]. b. The second row of AB is... Problem 17E: If A=[1225] and AB=[121693], determine the first and second columns of B. Problem 18E: Suppose the first two columns, b1 and b2, of B are equal. What can you say about the columns of AB... Problem 19E: Suppose die third column of B is die sum of die first two columns. What can you say about the third... Problem 20E: Suppose the second column of B is all zeros. What can you say about the second column of AB? Problem 21E: Suppose the last column of AB is entirely zero but B itself has no column of zeros. What can you say... Problem 22E: Show that if the columns of B are linearly dependent, then so are the columns of AB. Problem 23E: Suppose CA = In (the n n identity matrix). Show that the equation Ax = 0 has only the trivial... Problem 24E: Suppose AD = Im (the m m identity matrix). Show that for any b in m, the equation Ax = b has a... Problem 25E: Suppose A is an m n matrix and there exist n m matrices C and D such that CA = In and AD = Im.... Problem 26E: Suppose A is a 3 n matrix whose columns span 3. Explain, how to construct an n 3 matrix D such... Problem 27E: In Exercises 27 and 28, view vectors in n as n 1 matrices. For u and v in n the matrix product uTv... Problem 28E: If u and v are in n. how are uTv and vTu related? How are uvT and vuT related? Problem 29E: Prove Theorem 2(b) and 2(c). Use the row-column rule. The (i, j)-entry in A(B + C) can be written as... Problem 30E: Prove Theorem 2(d). [Hint: The (i, j)-entry in (rA)B is (rai1)b1j + ... + (rain)bnj.] Problem 31E: Show that ImA = A when A is an m n matrix. You can assume Imx = x for all x in m. Problem 32E: Show that AIn = A when A is an m n matrix. [Hint: Use the (column) definition of AIn.] Problem 33E: Prove Theorem 3(d). [Hint: Consider the jth row of (A B)T.] Problem 34E: Give a formula for (A Bx)T, where x is a vector and A and B are matrices of appropriate sizes. format_list_bulleted