# taking intro to ordinary differential equations; need some help

• September 17th 2008, 02:40 PM
valguerra
taking intro to ordinary differential equations; need some help
If somebody can help me how to solve couple of equations:

tandr + 2rDo=0

(x+4)(y^2+1)dx +y(x^2+3x+2)dy=0

(2xy+3y^2)dx-(2xy+x^2)dy=0

is first oder equations
• September 17th 2008, 11:24 PM
CaptainBlack
Quote:

Originally Posted by valguerra
If somebody can help me how to solve couple of equations:

tandr + 2rDo=0

this is incomprehensible

Quote:

(x+4)(y^2+1)dx +y(x^2+3x+2)dy=0
this is of variables seperable type:

$\frac{dy}{dx}=-\frac{(x+4)(y^2+1)}{y(x^2+3x+2)}=-\frac{x+4}{x^2+3x+2}\ \frac{y^2+1}{y}$

$\frac{y}{y^2+1}\frac{dy}{dx}=-\frac{x+4}{x^2+3x+2}$

RonL