x=3,y=-x+5(x＞1) y=-x+5(x≤1),y=?

（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)/(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=3,y=-x+5(x＞1) y=-x+5(x≤1),y=? 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 用递归法求y=x-(x*x*x/3!)+(x*x*x*x*x/5!)-(x*x*x*x*x*x*x/7!)+. 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 （2x+y-1)(2x-y+1)-(3x+y)(3x-y),其中x=5分之1, 化简 x / y(x+y) - y / x(x+y) = 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； 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 推倒公式:(x+y)(x*x-3x+y*y)=x*x*x+y*y*y怎么做. y(x+y)+(x-y)²-（x+y）（x-y）,其中x=-1/3,y=3 y=x(x x+y=1 5x-2y=8 3x-y=7 2x-y=3x表示y和用y表示x