已知M=x^2/x-y - y^2/x-y,N=(x+y)^2-2y(x+y),小敏和小丽两人在x=2,y=-1的条件下
已知P=X+Y,Q=(X-Y)(X-Y)-2Y(X+Y).小敏、小聪两人在X=2,Y=-1的条件下分别计算了P和Q的值.
已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
已知集合M={(x,y)|x^2+y^2=0},N={(x,y)||x|+|y|
已知4x=9y求(1)x+y/y (2)y-x/2x
已知P=x²/x-y-y²/x-y,Q=(x+y)²-2y(x+y),小红、小华两人在x=
若全集I={(x,y)|x,y∈R},集合M={(x,y)|(y-3)/(x-2)},N{(x,y)|y=x=1},则(
数学题已知p=x^/x-y-y^/x-y,q=(x+y)^-2Y(X+Y),
已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值?
先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y
已知2/x+2/y=根号24,求 x/y(x-y) - y/x(x-y)的值
已知2/x 2/y=根号24,求 x/y(x-y) - y/x(x-y)的值