2x-7(7x-2y)-2(x+6y)

3(x-y)^2-7(x-y)+8(y-x)^2+6(y-x)合并同类项. 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 计算：(x-y)^7÷(y-x)^6+(-x-y)^3÷(x+y)^2 2(y-x)的平方-7(x-y)+6(x-y)-3(y-x)的平方 计算(x-y)^7÷(y-x)^6+9-x-y)^3÷(x+y)^2 【2(x-y)(x-y)(x-y)-8(x-y)(x-y)(x+y)+6y(x-y)(x-y)]/2(x-y)(x-y) 化简3(x-y)-7(x--y)+2(y-x) 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) -6x-y-7x+6x-2y-10x+8y+x+6x-8y的值 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) -8(2x-y)-{7x-[6x+2y-(10x-8y)]}等于多少? 3x+5y-(x+y)=6 2(x+y)-3x=-7 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 将(x-y)看成一个整体,将3(x-y)²-4(x-y)+7(x-y)-6(y-x)²-2(y-x)合并同类项. x+2y=2x+y+1=7x-y 求：2x-y? (-3x+7y)(-7y-3x)-(x-3y)(2x+3y) 解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7