若5x-4y=6,4x-5y=8,则x+y=( ),x-y=( )
若5x+3y=3x+4y=x+2y+6,则x+y=___
已知x*x+4x+y*y-2y+5=0,则x*x+y*y=?
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*
若2x-3y+4=0则x(x*x-1)+x(5-x*x)-6y+7
(5x+3y)(3y-5x)-(4x-y)(4y+x)=
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
已知:4x = 5y,求(x+y) :y
若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( )
(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai
x-y+5x-4x= ?
若x/y=4/3 则3x+2y/2x-5y=
若4x-5y=0,则x+y分之x-y的值是