Question

化简求值 【2x²-(x+y)(x-y)][(x+y-1)(x-y+1)+1-2y],其中x=-1，y=-2

帮帮忙吧！我思考了很久还没想出来，这是我的暑假作业的一道题，谢谢！

Answer 1

【2x²-(x+y)(x-y)][(x+y-1)(x-y+1)+1-2y],
=(2x²-x²+y²)[x²-(y-1)²+1-2y]
=(x²+y²)(x²-y²+2y-1+1-2y)
=(x²+y²)(x²-y²)
=X^4-Y^4
把x=-1,y=-2代人上式得：
(-1)^4-(-2)^4
=1-16
=-15

Answer 2

结果是x的4次方－y的4次方
带入x，y的值，得﹣15