Diketahui matriks A = (2 -1 1 4), B = (x+y 2 3 y), dan C =

Diketahui matriks A = (2 -1 1 4), B = (x+y 2 3 y), dan C = (7 2 3 1). Apabila B-A=C'= transpos matriks C, maka nilai x.y= ....