若2x+y/3=x+3y/5=1,则3x+4y=

化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 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 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( ) {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 若5x+3y=3x+4y=x+2y+6,则x+y=___ 若x/y=4/3 则3x+2y/2x-5y= 若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( )