2x-5y=7 2x+3y=1 求x,y等于几

(x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 x+2y=2x+y+1=7x-y 求：2x-y? 1、(-y^3)^5/y^3/ y^2+2(-y)^102、(x-y)^7/(y-x)^6+(x+y)^3/(x+y)^23、已知X^a=5,x^b=3,求X^(3a-2b)的值 已知(3x+1)(3x-3)-3x+2)^2=-7,(y+7)(y-7)-y(y-7)=0,求8y^2-5y(-y+3x)+4y(-4y-5/2x)的值 若x-y=2(x+y),求代数式x-y/x+y+x+y/x-y求代数式 x+y分之x-y+x-y分之x+y 已知:y=ax的3次方+bx+3,当x=-1/2时,y=-7,试求x=1/2时,y的值 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值 {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 已知2x-y=-3,求代数式5(x-3y)-2(x-7y) 4x-3y=5 x^2+y^2=1 求x,y 3x+4y-5=0 x^2+y^2=1求x.y