若x^2-y^2=40 x+y=8/5 则x-y=——
若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于
若3x-5y=0,则x+y/x=(),x-y/y=(),2x-3y/2x+3y=( )
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
设x>1,y>0,若x^y+x^-y=2根号2,则x^y-x^-y等于
已知x*x+4x+y*y-2y+5=0,则x*x+y*y=?
若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( )
若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*
【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=
若5x+3y=3x+4y=x+2y+6,则x+y=___
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—y)的2次方×(x—y)的5次方×(y-x)=()
若x/y=4/3 则3x+2y/2x-5y=