1/4x-3y=8 y-2x=5
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)+...-(
(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+(
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
9y=3x-(x-1),4(x+y)-(2x+4)=8y
若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( )
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
3x-2y=1 4x-5y
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
化简求值{(x=2y)(5x-2y)-(3x+2y)(3x-2y)]/4x,其中x=2,y=-1