{x+y=7 {3x+y=17

把(x-y)看作一个整体,化解:5(x-y)+2(x-y)-4(x-y)= 3(x-y)把(x-y)看作一个整体,化解:5(x-y)+2(x-y)-4(x-y)=3(x-y)²-4(x-y)+7(x-y)-6(x-y)²= x+y =7 3x+y=17 {x+y=7 {3x+y=17 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 初二上学期方程题 4x+y=5 5x+4y=63x-2y=1 2x+3y=13x-2y=7 7x+5y=32x+3y=17 2x-y=-4x+5y=6 2x+y=23x-6y=4 3x+2y=52x+y=73x-4y=53x+y=1x-2y=-1x+y=42x+3y=92x-3y=74x+5y=3x+y=20004x+6y=90003x+5y=113x-2y=42x+3y=215x-2y=5x+y=54x+3y=182x+3y=16x+4y=132x+3y=40x 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 （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. 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 x+y=5; x^y+y^x=17 7y(x-3y)-2(3y-x)=0 .x=?,y=? (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) =