已知丨x+3丨+丨y-x+4丨=0,求(x-y)(x+y)的值 越快分越多.

问题描述:

已知丨x+3丨+丨y-x+4丨=0,求(x-y)(x+y)的值 越快分越多.

丨x+3丨+丨y-x+4丨=0
丨x+3丨=丨y-x+4丨=0
x+3=0,y-x+4=0
x=-3,y=-7
(x-y)(x+y)=4*(-10)=-40