Science:Math Exam Resources/Courses/MATH152/April 2017/Question A 23/Statement

Let $A$ and $B$ be matrices and let ${\mathbf {x}}$ be a vector. If $(A{\mathbf {x}})^{T}B$ is an $4\times 7$ matrix, is ${\mathbf {x}}$ a row vector or a column vector, and how many entries does it have? Justify your answer.