(1) {3x-y=5 {5y-1=3x+5 (2) {2x>1-x {x+21+2x {3x+2

(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 5(x-y)³-3（x-y）²+7(x-y)-5(x-y)³+（x-y）²-5（x-y）,其中,x-y=1/3.5(x-y)³-3（x-y）²+7(x-y)-5(x-y)³+（x-y）²-5（x-y）,其中,x-y=1/3先化简,再求值； （x+y-5)*（x+y-5)+（x-y+3)=0 x*x-y*y 已知:3x-5y=0,求x/y,x-y/y,x-y/x x+y=1 5x-2y=8 3x-y=7 2x-y=3x表示y和用y表示x （2x+y-1)(2x-y+1)-(3x+y)(3x-y),其中x=5分之1, (x+2y)(x-2y)-(2x-y)的平方+(3x-y)(2x-5y)其中x=-1 y=13分之1 y''-5y'+6y=3x+1通解 {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 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 3X+5y=2 x+y=1 3x-2y=1 4x-5y {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 化简求值(x+2y)^2-(2x+y)(2x-y)-5y(y-x) 其中 x=1/3 y= -1/2 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