先化简,再求值(x+y/2)^2-(x-y/2)^2,其中x=-1/16,y=8

问题描述:

先化简,再求值(x+y/2)^2-(x-y/2)^2,其中x=-1/16,y=8

(x+y/2)^2-(x-y/2)^2
=(x+y/2+x-y/2)(x+y/2-x+y/2)
=2x*y=2xy
x=-1/16,y=8时
2xy=2*(-1/16)*8
=-1