2x+5y=1/2,3x-5y=1/3还有1道：x/2+Z/3=7,x/3-z/4=-1 //////用加减法

(x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 （2x+y-1)(2x-y+1)-(3x+y)(3x-y),其中x=5分之1, x+y=1 5x-2y=8 3x-y=7 2x-y=3x表示y和用y表示x (x+2y)(x-2y)-(2x-y)的平方+(3x-y)(2x-5y)其中x=-1 y=13分之1 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) {x+y=1 ,xy=-6{x(2x-3)=0,y=x²-1{(3x+4y-3)(3x+4y+3)=0,3x+2y=5{(x-y+2)(x+y)=0,x²+y²=8{(x+y)((x+y-1)=0,(x-y)(x-y-1)=0 3X+5y=2 x+y=1 3x-2y=1 4x-5y 化简求值(x+2y)^2-(2x+y)(2x-y)-5y(y-x) 其中 x=1/3 y= -1/2 {x+y}/2+{x-y}/3=5 {x+y}/2-{x+y}/3=-1 解二元一次方程 3Q!| {x+y}/2+{x-y}/3=5 | {x+y}/2-{x+y}/3=-1 x-y/7 - x+y/10 =1/2 2(x-y)-5(x+y)=3修改、、、、（x-y)/7-(x+y)/10=1/2 2(x-y)-5(x+y)=3 (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 7x-3y/5=5x-y/3-x+y/2 x-1/5=y+1/3 x-{y-2x+[3x-3(y+2x)+5y]},其中=2分之1,y=-1 x-{y-2x+[3x-3(y+2x)+5y]},其中=2分之1,y=-1 解方程组{(x-2)(y+3)=(x+1)(y-1) {(x+1)(y+1)=(x-1)(y+5)