x-y=-3,3x+5y=31

（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 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) （5x+3y)(3y-5x)-(4x-y)(4y+x)= (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 已知x/5=y/3,则(x/x+y)+(y/x-y)-(yxy/xxx-yxy) x-y=-3,3x+5y=31 先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5 推倒公式:(x+y)(x*x-3x+y*y)=x*x*x+y*y*y怎么做. {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? |x|=3 |y|=5 |x-y|=|x|+|y| 求 X+Y和 X-Y 等于多少 6x+5Y=31 2X+3Y=17求X求 Y 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1