hi

i have to solve this

$\displaystyle \frac{dn}{dt} = f(t)n + g(t)$

i know the solution is

$\displaystyle n=e^{\mu(t)}(\int e^{-\mu(t)}g(t)dt + c)$

$\displaystyle \mu(t) = \int f(t) dt$

how do i arrive at this solution? do i just separate variables, can someone start me of or solve this so i can understand it

many thanks