Linear algebra

Compute each matrix sum or product if it is defined. If an expression is undefined, explain why. Let A = -5 -6 - 3A, B - 3A, AC, CD Compute the matrix product - 3A. Select the correct choice below and, if necessary, fill in the answer box within your choice. - 3A = O A. (Simplify your answer.) O B. The expression - 3A is undefined because matrices cannot have negative coefficients. O c. The expression - 3A is undefined because A is not a square matrix. O D. The expression - 3A is undefined because matrices cannot be multiplied by numbers