{5x-2y=6 3x-2y=20这么解

{5x-2y=6 3x-2y=20这么解 (2x-y)(x+y)-(4x-5y)-6=(2x-y+2)(x+y-3) 为什么这么做,原理是什么? x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 解方程组;x+y/2=x-y/3=6 4(x+y)-3(x-y)=-20 解方程组 X+Y/2+X-Y/3=6 4[X+Y]-5[X-Y]=2 解二元一次方程：x+y/2+x-y/3=6 4(x+y)-5(x-y)=2 解二元一次方程组{x+y/2+x-y/3=6,4(x+y)-2=5(x-y) 解方程组2分之x+y+3分之x-y=6 4(x+y)-5(x-y)=2 解方程组 {(x+y)/2+(x-y)/3=6 5(x+y)-2(x-y)=4 解方程组：x+y/2+x-y/3=6 4(x+y)-5(x-y)=12 解方程组：3(x+y)+2(x-y)=11,6(x+y)-5(x-y)=13. 解方程组：x+y/2+x-y/3=6,（x+y）+5（x-y）=38 谢. 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=