x+y=15 2X+1/2Y=15
10/x+y+3/x-y=-5 15/x+y-2/x-y=-1(用换元法解此方程组)
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
x+2y=3 x+y+z=36 2x+y+z=15 2y=3z x-y=1 x+2y+z x-z=-1 2x+z-y=1
(3x-y)^2+(3x+y)(3x-y),x=1,y=-2
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
已知4x=9y求(1)x+y/y (2)y-x/2x
y=(x^2+x)/(x+1)
[x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013
2(x+y) 3x+3y=24 x+y/2x x y/2y= 1
设x>1,y>0,若x^y+x^-y=2根号2,则x^y-x^-y等于
已知2x+2y=-8,4x+y=15求(x-y)^-(3x+2y)^
解方程x+y+(x+y/2)=15 3x+5y+4(x+y/2)=62