2.1 EXERCISES In Exercises 1 and 2, compute each matrix sum or product if it is defined. If an expression is undefined, explain why. Let 2 0 -1 4 -5 2 3 2] D= [-³ 1. -2A, B - 2A, AC, CD A = c = [₁ C 1 -2 4 3. Let A = [4 [$ A = - B 5 -2 -11 2. Let A be a 4 A²x? Count the multiplica 3. Suppose A is an m x n mat matrix, all of whose colum = 2. A + 2B, 3C - E, CB, EB In the rest of this exercise set and in those to follow, you should assume that each matrix expression is defined. That is, the sizes of the matrices (and vectors) involved "match" appropriately. Compute 312 - A and (31₂) A. 7 -5 -4 Compute A - 513 and (513)A, when 9 -1 3 -8 7 -6 -4 1 8 - E = -5 3 In Exercises 5 and 6, compute the product AB in two ways: (a) by the definition, where Ab, and Ab2 are computed separately, and (b) by the row-column rule for computing AB. 5 7 8 10. 11.