Question

Let A be 3×4 matrix, B be a 3×5 matrix and C a 3×4 matrix, then A.C^T. B + 2B.B^T is (a) a 3×5 matrix. (b) a 3×4 matrix. (c) a 3×3 matrix. (d) a 4×3 matrix. (e) Not defined.

Answer 1

Hi,

Explanation:

answer E: not defined

A: [3,4]
B: [3,5] => B^T:[5,3]

C: [3,4] => C^T:[4,3]

A.C^T => [3,4]*[4,3]=[3,3]

A.C^T.B => [3,3].[3,5]=[3,5]

2.B => [3,5]

2.B.B^T => [3,5].[5,3] = [3,3]

impossible to add [3,5] and [3,3]