Возьмём 2-ое выражение и упростим его:
(16у+х^2) / xy-x-4y+4 = (16y+x^2) / [(xy-x)-(4y-4)] = (16y+x^2 ) / [x(y-1) -4(y-1)] = (16y+x^2)/[(x-4)(y-1)]
Далее выполняем действие задания:
(x^2y+16)/[(y-1)(x-4)] - (16x^2+x^2)/ [(y-1)(x-4)] =( x^2y +16-16y-x^2) /[(y-1)(x-4) =
=[(x^2y-x^2) -(16y+16)] / [(y-1)(x-4) = [x^2(y-1)-16(y-1)] / [(y-1)(x-4)] = [(y-1)(x^2-16)] /[(y-1)(x-4) =
=[(x^2 -4^2)] / (x-4) = [(x-4)(x+4)] / (x-4) = x+4