先化简再求值：已知2x+y=1/2,xy=2,求(x^3y^4-2x^4y^3)^3的值
问题描述：
先化简再求值：已知2x+y=1/2,xy=2,求(x^3y^4-2x^4y^3)^3的值
答
解；
(x^3y^4-2x^4y^3)^3
=[x^3y^3（y-2x)]^3
=[(8*(-1/2)]^3
=(-4)^3
=-64
答
(x^3y^4-2x^4y^3)^3
=[ x³y³(y-2x)]³
=-[(xy)³]³ (2x-y)³
=-8³ ×1/8
=-64