b) (x – y)^2 – x(x + 2y);
b) (x – y)2 – x(x + 2y);
b) (x – y)2 – x(x + 2y)
= x2 ‒ 2xy + y2 ‒ x2 ‒ 2xy
= (x2 ‒ x2) + (‒2xy ‒ 2xy) + y2
= ‒4xy + y2.