问题标题:
1/2(x+y)^5+2(x+y)^2-4/3(x+y)^3-1/2(x+y)^5+1/3(x+y)^3,其中x=3-y
问题描述:
1/2(x+y)^5+2(x+y)^2-4/3(x+y)^3-1/2(x+y)^5+1/3(x+y)^3,其中x=3-y
胡金莲回答:
1/2(x+y)^5+2(x+y)^2-4/3(x+y)^3-1/2(x+y)^5+1/3(x+y)^3
=-(x+y)³+2(x+y)²
x=3-y
∴x+y=3
∴原式=-3³+2*3²
=-27+18
=-9
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