-（x+y)+(3x-7y)

化简3(x-y)-7(x--y)+2(y-x) (3x+y)(3x-7y) -（x+y)+(3x-7y) (3x-y)(3y+x)-(x-y)(x+y) x-4y分之3x + 4y-x分之x+y - x*x-4y分之7y (-3x+7y)(-7y-3x)-(x-3y)(2x+3y) 18(x+y)^8(x-y)^7÷[3(x+y)^3(x-y)^3]^2 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 (3x-4y)(5x-4y)-(7x-8y)(6y-5x) 因式分解：(x-y)(3x-7y)²-4(x-y)(x+y)² 方程(X+Y)/X*X-X*Y+Y*Y等于3/7的所有正整数解 计算：(x-y)^7÷(y-x)^6+(-x-y)^3÷(x+y)^2 3(x+y)的平方-7(x-y)-9(x+y)的平方-6(x-y) 3(x-y)^2-7(x-y)+8(y-x)^2+6(y-x)合并同类项. 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 化简:3(x-y)²-7(x-y)+ 2(x-y)²+5(x-y) 计算(x^8-x^7y+x^5y^3-x^4y^4+x^3y^5-x^y^7+y^8)(x^2+xy+y^2)