Question

(-x-y+2y)的平方是多少？

Answer 1

(x y)的平方-(x y)的平方=[(x y)(x y)][(x y)-(x y)]=(x y x y)(x y y y)= 2x * 2y = 4xy
(x y)的平方-(x y)的平方=[(x y)(x y)][(x y)-(x y)]= 2x×2y = 4xy
(x y)的平方-(x y)的平方= (x y x y) (x y x y) = 2x * 2y = 4xy。如果不理解，请接受。谢谢大家！
(x y)-(x y) = x y 2xy-(x y 2xy) = 4xy这是平方和的公式(x y)=(x y)*(x y)= x * x x * y y y * y = x 2xy y(x y)=(x y)
= {(x y)(x-y)} * {(x y)-(x-y)} = 2x * 2y = 4xy

Answer 2

（一x一y十2y）²=（y一x）²
=（y一x）（y一x）
=y²一2xy十x²