作业帮先化简再求值 [2x²-(x+y)(x-y)]·[(-x-y)(y-x)+2y²] 其中x=1y=2
来源：学生作业帮助网 编辑：作业帮 时间：2024/04/27 15:15:04
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先化简再求值 [2x²-(x+y)(x-y)]·[(-x-y)(y-x)+2y²] 其中x=1y=2
先化简再求值 [2x²-(x+y)(x-y)]·[(-x-y)(y-x)+2y²] 其中x=1y=2
先化简再求值 [2x²-(x+y)(x-y)]·[(-x-y)(y-x)+2y²] 其中x=1y=2
[2x²-(x+y)(x-y)]·[(-x-y)(y-x)+2y²]
=(2x^2-x^2+y^2)(x^2-y^2+2y^2)
=(x^2+y^2)(x^2+y^2)
=(x^2+y^2)^2
代入x y
=25
[2x²-(x+y)(x-y)]·[(-x-y)(y-x)+2y²]= [2x²-x²+y²]·[x²-y²+2y²]=(x²+y²)²=(1+4)²=25