化简求值:2xy-1/2(4xy-8x^2y^2)+2(3xy-5x^2y^2),其中x=1/2,y=-2/3

问题描述:

化简求值:2xy-1/2(4xy-8x^2y^2)+2(3xy-5x^2y^2),其中x=1/2,y=-2/3

原式=2xy-2xy+4x^2y^2+6xy-10x^2y^2
=6xy-6x^2y^2
=6xy(1-xy)
xy= - 1/3 ∴原式= - 2X4/3= - 8/3