已知x=22/75,y=25/44,求(x+y)-(x-y)

问题描述:

已知x=22/75,y=25/44,求(x+y)-(x-y)

(x+y)-(x-y) =[(x+y)+(x-y)][(x+y)-(x-y)]=(2x)(2y)=4xy=4×22/75×25/44=2/3