Question

if A and B are matrices AB=0 then find x and y

Answer 1

When you are given with the matrix A and B, multiply them. Then equate the result with the Zero Matrix. It is because 0 in Matrix is Zero Matrix. A zero matrix is a square matrix with only zeroes. Now you will get equation with x and y. Note the AB matrix would be having x and y as their elements in some place. Then you will get the answer.