问题
解答题
计算:(x-y)2-(-x+y)(x+y)
答案
(x-y)2-(-x+y)(x+y)=x2-2xy+y2-(-x2-xy+xy+y2)=x2-2xy+y2+x2+xy-xy-y2=2x2-2xy;
计算:(x-y)2-(-x+y)(x+y)
(x-y)2-(-x+y)(x+y)=x2-2xy+y2-(-x2-xy+xy+y2)=x2-2xy+y2+x2+xy-xy-y2=2x2-2xy;