2x+9y=81 3x+y=34
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)
5x=3y,(2x+y)的平方=5x(x+y)+9
9y=3x-(x-1),4(x+y)-(2x+4)=8y
3x-2y=9 x-3y=2 x+y=5 x+2y=3 y=x 2x+y=8
3y=2x y/3=x/2 12/x=9/y y/x=?y/x=?x/y=?
已知2x-y/x+2y=3,求2(2x-y)/x+2y-9(x+2y)/2x-y+3的值.
【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=
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
{4/(x+y)+6/(x-y)=3 {9/(x-y)-1/(x+y)=1
(3x-y)^2+(3x+y)(3x-y),x=1,y=-2
已知4x=9y求(1)x+y/y (2)y-x/2x