(3x^2+1/2y-2/3y^2)*(-1/2xy)^2

x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² x(x-y)2-(y-x)3 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 计算：x+2y/x-y+2x/y-x-3y/x-y 化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方 [(3x+y)(x-y)-(2x+3y)(x-y)]*(x-y) (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 二元一次方程 ：2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 2(x+y)-3(x-y)=1 6(x+y)+(x-y)=51 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 变量x,y满足约束条件,x+y>=3,x-y>=-1,2x-y (Y-X)^3*(X-Y)^m+(X-Y) ^m+1*(Y-X)^2 (x-y)^2+(x+y)(x-y) 其中 X =3 Y=-1 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) x+y+2(-x-y+1)=3(1-y-x)-4-(y+x-1),x+y=? 2X(2X-3Y)-3Y(X+Y) (-2x y)^2-(3y-x)(-x-3y)