If A is 3 × 4 matrix and B is a matrix such that A′B and BA′ are both defined. Then B is of the type

Let the order of B be m × n.Since A is 3 × 4 matrix,∴ A′ is 4 × 3 matrix.Since A′ B is defined,∴number of columns of A′ must be equal to number of rows of B,∴ m = 3.Also, since BA′ is defined,∴ number of columns of B must be equal to number of rows of A′,∴ n = 4.∴B is 3 × 4 matrix