[2x²-(x+y) (x-y)] [(-x-y) (y-x)+2y²] 其中x=1,y=2

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[2x²-(x+y) (x-y)] [(-x-y) (y-x)+2y²] 其中x=1,y=2
数学：[2x²-(x+y) (x-y)] [(-x-y) (y-x)+2y²] 其中x=1，y=2

[2x²-(x+y) (x-y)] [(-x-y) (y-x)+2y²]
=[2x²-(x²-y²)][(x+y)(x-y)+2y²]
=(2x²-x²+y²)(x²-y²+2y²)
=(x²+y²)²
=(1²+2²)²
=5²
=25
再问：请问一下就是原式那个答案在哪呢？25是正确答案，25的上一个式子的答案在哪里？
再答： [2x²-(x+y) (x-y)] [(-x-y) (y-x)+2y²] =[2x²-(x²-y²)][(x+y)(x-y)+2y²] =(2x²-x²+y²)(x²-y²+2y²) =(x²+y²)² =(1²+2²)² =(1+4)² =5² =25

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