用消元法求2x+3y=0、3x+5y=—1(急,
用消元法求2x+3y=0、3x+5y=—1(急,
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
急!急!两道高数题!xy"+y'^2=y'求其通解;y"=(1+y')^3/2求:当y"|(x=0)=0,y'|(x=0
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)+...-(
微分方程(1)(y'')^2+5y'-y+x=0;(2)y''+5y'+4y^2-8x=0;(3)(3x+2y)dx+(
若2x-3y+4=0则x(x*x-1)+x(5-x*x)-6y+7
若3x-5y=0,则x+y/x=(),x-y/y=(),2x-3y/2x+3y=( )
(2x+y-1)(2x-y+1)-(3x+y)(3x-y),其中x=5分之1,
已知x/3=y/5=z/4,求x+y+z/y和x+y-z/y-x的值,2种方法.急等.
已知X,Y,满足(X+3Y)(X-3Y)=-10(Y^2-6/5)和2X(Y-1)+4(1/2X-1)=0