Question

先化简在求值﹙x+y﹚²-2﹙x+y﹚﹙x-y﹚﹢﹙x-y﹚²,其中,x=-2013分之一,y=-5

Answer 1

(x+y)²-2(x+y)(x-y)+(x-y)²

=[(x+y)-(x-y)]²

=(2y)²

=4y²

=4×(-5)²

=100