已知(4x-2y -1)^2+根号xy-2=0 求4x^3Y-4x^2Y^2+xY^3
问题描述:
已知(4x-2y -1)^2+根号xy-2=0 求4x^3Y-4x^2Y^2+xY^3
答
由题意知:
4x-2y -1=0
xy-2=0
于是有,2x-y=1/2,xy=2
所以4x^3Y-4x^2Y^2+xY^3
=4x^3Y-2x^2y^2-2x^2y^2+xY^3
=2x^2y(2x-y)-xy^2(2x-y)
=(2x-y)(2x^2y-xy^2)
=xy(2x-y)(2x-y)
=2*(1/2)*(1/2)
=1/2