We have just had an introduction to differential equations, and I need a little help as I left a bit confused and am still fumbling around with two problems:

Suppose $\displaystyle Q=Ce^{-kt}$ and that $\displaystyle \frac {dQ} {dt} = -0.06Q$

What does this say about k and C?

At this point, I thought that $\displaystyle k = -.06$ and that $\displaystyle C$ could be any value at all, but there are apparently two different answers and I am not sure if what I had mentioned before is even correct.

The other one that I am having troubles with is:

$\displaystyle

x\frac{dy} {dx} - 4y = 0$

I found that the general solution was $\displaystyle Cx^4$, but the problem asks for a second solution $\displaystyle y=Cx^n$ that might not be a general solution and which may have a different value of n than the one that was previously found. Could the answer be $\displaystyle y=0$ or is there an other answer that I am just not thinking of?

Thanks for the help everyone.