Write the element of a 3 × 3 matrix A = () whose elements are given by

Let A and B are matrices of order 3 x 2 and 2 x 4 respectively. Write the order of matrix (AB).
Write the value of λ so that the vectors = and = are perpendicular to each other ?
Let f : {1, 3, 4} → {1, 2, 5} and g : {1, 2, 5} → {1, 3} given by f = {(1, 2) (3, 5) (4, 1)} and g = {(1, 3), (2, 3), (5, 1)} Write down gof.