3(2x-7y)(7y+2x)+(4x+5y)(-5y-4x)

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) x^8-x^7y+x^6y^2-x^5y^3+x^4y^4-x^3y^5+x^2y^-xy^7+y^8 (3x-4y)(5x-4y)-(7x-8y)(6y-5x) （x+2)(x+3) (x-4)(x+1) (y+4)(y-2) (y-5)(y-3) 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 化简2（2X-7Y)(7Y+2X)+X^2-(-4X+5Y)(-5Y-4X) 3(x-y)-2(x+y)-5(x-y)+4(x+y)+3(x-y) 化简合并同类项 1) (2x+5y)(2x-5y)(-4x^2-25y^2) 2) [（x+y)(x-y)-(x-y)^2+2y(x-y 计算:1/(x-y)-1/(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8x^7/(x^8+y^8 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 先化简在求值 （x+5y）（x+4y）-（x-y）（x+y）,其中,x=-2又2/3,y=3/7