4x^2-3x^2-( )=5x^2+4xy-3y^2
(-3x^y+2xy)-( )=4x^+xy
[-(x-y)^2/xy]^-4*(y^2-xy/x)^3*(x^4/y^10)÷(xy-y^2/x)^-5=-y(y-
已知(x+2)^2+|x+y+5|=0,求3x^2y-[2x^2y-(2xy-x^2y)-4x^2]-xy
已知(x+2)^2+|x+y+5|=0,求3x^2y+{-2X^2y-[-2xy+(x^2y-4x^2)]-xy}
已知x,y>0 2x+y+3=xy 求5x+4y最小值
x^3y(-4y)^2+(-7xy)^2*(-xy)-5xy^3*(-3x)^2
已知x-y=4xy,则2x+3xy-2yx-2xy-y
若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( )
已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)}
5xy平方-2x平方y+[3xy平方-(4xy-2x平方y-2x平方y)],其中x=-2,y=-1求值
x*-2xy+3y*=9 4x*-5xy+6y*=30
已知x-y=4xy,求x-2xy-y分之2x+3xy-2y的值!