x-3y=-203x+7y=1003x-4y=105x+6y=42用代入法解方程写在纸上发给我谢谢

若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 （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 推倒公式:(x+y)(x*x-3x+y*y)=x*x*x+y*y*y怎么做. x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 计算3x/(x-3y)+(x+y)/(4y-x)-7y/(x-4y)=? 若x,y为正整数,且满足3x(x+y)-y(x+y)=7,求x,y 化简 x / y(x+y) - y / x(x+y) = 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 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!)+. (x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) x(x+y)(x-y)-y(y+x)(y-x)=(x-y)( )填空 7x:4y,x:y=( ):( 化简 x-y/(y-x)^3= (x+y)(2x-3y)=? y=x(x