1.(3x+2y)/4=(2x+5)/5

3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 1.已知:x-2y=3,求[(3x+2y)(3x-2y)-(x+2y)(5x-2y)]除4x 的值 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 数学题……555{(3x+y)(3x-y)-(x-5y)(5x-y)-(x-2y)²÷(-4x),x=-2.y 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai （x+2)(x+3) (x-4)(x+1) (y+4)(y-2) (y-5)(y-3) 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 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)