｛3x+5（x+y）=36 3y+4（x+y）=36 二元一次的解法 每种都要

3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 （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 （5x+3y)(3y-5x)-(4x-y)(4y+x)= （x-y）^3×（y-x）^4+（x-y）^2×（y-x）^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/2=6 3(x+y)=4(x-y) （x+y）^6/(x+y)^4-(x-y)^5/(x-y)^3 化简 .. 先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5 3x+3y+2x-2y=36 4x+4y-5x-5y=2 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 解方程组 x+2y=3（x+y）+5 3x-4y=4（x+y）-15 (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) -4（y-x）-3x+3y+5,其中x-y=3 因式分解(x-2y)(x-3y)+(x-4y)(x-5y)+（x-3y)(x-5y)+(x-2y)(x-4y) 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1