x+2y=9 3x－2y=-1 5x+2y=25 3x+4y=15 2x+3y=x+2y=9 3x－2y=-1 5x+2y=25 3x+4y=15 2x+3y=6 3x－2y=-2 x+2y=9 3x－2y=-1 解二元一次方程组,,解出来

4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 (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=? x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 (x-y)/4+(x+y)/5=1/4 (x+y)/9-(x-y)/3=//2(x-y)/4+(x+y)/5=1/4(x+y)/9-(x-y)/3=//2 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 解方程组 3(x+y)-2(x-y)=9,5(x+y)+2(x-y)=-1 解方程组:{3(x+y)-2(x-y)=9,5(x+y)+2(x-y)=-1} 3x(2x＋y)－2x(x-y),其中x＝1,y=1/5 5x=3y,(2x+y)的平方=5x(x+y)+9 9y=3x-(x-1),4(x+y)-(2x+4)=8y （2x+y-1)(2x-y+1)-(3x+y)(3x-y),其中x=5分之1, x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2