Solution of a simple differential equation, but now I forget it

Question

$\frac{dp}{dr}+\frac{p}{r}$=0

what's p?

It was originally a simple equation......

I have learned this part of knowledge before, but now I forget it......thanks

Answer 1

$$\dfrac{dp}{dr}r+p=0$$

Or more generally

$$\dfrac{dp}{dr}F(r)+G(p)=0$$

Is a linear first order homogeneous ODE. As suggested in the comments can be solved by separation of variables or integrating factor.