先化简再求值.1/2-(-3/2x+1/3y2)+(2x-2/3y2),
问题描述:
先化简再求值.1/2-(-3/2x+1/3y2)+(2x-2/3y2),
答
1/2+(-3/2x+1/3y2)-(2x-2/3y2)
原式=1/2-2x+2/3y^2-3/2x+1/3y^2
=1/2-7/2x+y^2
其中x=-1/4,y=-1/2
原式=1/2+7/8+1/4
=13/8