先化简,再求值:(6x-2y)*3/2xy^2-(xy-3)(xy+1)-(3x-4y)(3x+4y)+(2x-1/2y)^2其中x=-2,y=1/2要过程,

问题描述:

先化简,再求值:(6x-2y)*3/2xy^2-(xy-3)(xy+1)-(3x-4y)(3x+4y)+(2x-1/2y)^2
其中x=-2,y=1/2要过程,

个人觉得,不如直接计算6x-2y=-12-1=-132xy^2=2*(-2)*1/4=-1所以(6x-2y)*3/2xy^2=(-13)^3/(-1)=2197xy=-1(xy-3)(xy+1)=0(3x-4y)(3x+4y)=9x^2-16y^2=9×4-16×1/4=32(2x-1/2y)^2=(-4-1/4)^2=18.0625原式=2197-0-32+18...