已知:x+y=1,xy=-1/2,求:(x+y)²(x-y)+2y²(x+y)的值.
4个回答
(x+y)²(x-y)+2y²(x+y)
=(x+y)(x²-y²+2y²)
=(x+y)(x²+y²)
=(x+y)[(x+y)²-2xy]
=1×【1-2×(-1/2)】
=2
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