3x-2y=1 5x+3y=8
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
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
已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(
【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=
已知:3x=8y.求(1)x+y/y (2)2x+3y/x-2y
(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai
微分方程(1)(y'')^2+5y'-y+x=0;(2)y''+5y'+4y^2-8x=0;(3)(3x+2y)dx+(
9y=3x-(x-1),4(x+y)-(2x+4)=8y
3x-2y=9 x-3y=2 x+y=5 x+2y=3 y=x 2x+y=8
(2x+y-1)(2x-y+1)-(3x+y)(3x-y),其中x=5分之1,
若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( )