Question

Please help! Correct answer only, please! Matrix C has the dimensions 7 X 2 and Matrix D has the dimensions 2 X 7. Determine the dimensions of the matrix CD, if it is possible. Explain why if it is not. A. Matrix CD would have the dimensions 2 X 2 B. Matrix CD would have the dimensions 2 X 7 C. Matrix CD would have the dimensions 7 X 7 D. These matrices cannot be multiplied because their dimensions don't align.

Answer 1

Answer: C) CD has dimensions 7 x 7

Explanation:

When multiplying matrices the number of rows of the first matrix MUST equal the number of columns of the second matrix. I call these the "inside" numbers. The resulting dimension will be the "outside" numbers.

[7 x 2] × [2 x 7]

↓ ↓

inside These must match!

[7 x 2] × [2 x 7]

↓ ↓

outside These are the dimensions!

7 × 7 are the dimensions of CD