计算题 xy【y^2+x^2】-y^2【xy+2x】-3xy

(2×y+x²-y²)-(x²-y²-3xy) 计算题, 计算题(-3x^2y^2+6x^2y^2-1/3xy)÷(-1/3xy) 计算题：(-3x^2y^3+6x^2y^2-1/3xy)÷(-1/3xy) （xy-x^2)乘以(xy)/(x-y) 一道计算题：(2x^3y^2-3x^2y+4xy^3)/(-2x)/(-y) (x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y) x^2-xy-6y^2+3xy+y+2 （x^2+xy/x-y)/（xy/x-y)计算 计算3xy[2xy-x(y-2)+x-1] 计算：3xy[2xy-x（y-2）+x] （-3x^y+2xy)-( )=4x^+xy 有这样一道计算题：“计算(2x-3xy-2xy)-(x-2x+y)+(-x+3xy-y)的值,其中“x=1/2,y=-1