x+Y=12, 100x:200y=3:2怎么计算

二元一次方程帮忙解下(1)12.5x+13.3y-200=12x+13.5y12.9x+13.9y-1300=12.5x+13.3y x=?y=?(2)200x+150y=5500150x+100y=4000 x=?y=?(3)x+y=68100x+y-100y-x=2178 x=?y=? 12y(x-y)^2-8(x-y)^3=? 3x+y=2 -y/x+y=123x+y=2 （-y/x）+y=12 （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 (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) 化简 x / y(x+y) - y / x(x+y) = 化简 x-y/(y-x)^3= (x+y)(2x-3y)=? (x*x+y*y)(x*x+y*y)-(x*x+y*y)=12 求x*x+y*y等于多少 3y=2x y/3=x/2 12/x=9/y y/x=?y/x=?x/y=? 求 X Y公式X+Y=50Y/X=3X+Y=100Y/X=3求 x y...公式 21/(x+y)+4/(x-y)=12/(x+y)+7/(x-y)结果为(x+y)/(x-y)=3求过程! 已知2x-y/x+3y=2,求代数式4x-2y/x+3y减4x+12y除以2x-y