x+y=8,x^2 - y^2=48 ,则y-x=()
【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=
[x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013
若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于
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)
(x+2y)(x-2y)-(2y-x)(-2x-y)其中x=8,y=-8
[(x+2y)(x-2y)-(x-2y)^2+8y(x+y)]除以4x=
已知x*x+4x+y*y-2y+5=0,则x*x+y*y=?
设x>1,y>0,若x^y+x^-y=2根号2,则x^y-x^-y等于
y'-2y=(e^x)-x
y'+2y/x=x通解
已知方程组{2x+y=7,x+2y=8,则x-y=(),x+y=().