Calculate integral for the function :
$\displaystyle \begin{array}{l}
\frac{{\sin (bx)}}{{e^{ax} }} \\
\frac{{\cos (bx)}}{{e^{ax} }} \\
\end{array}
$
Please post one problem per thread and try to show some effort. This is the third thread that you've posted a pair of integral problems without showing any work. I'm not saying that you haven't tried but you need to show us that, even if you can't start the problem. Say you tried this u-sub method, or thought it was this kind of situation, etc. but couldn't get anywhere.
You need to learn to use the \frac Latex command. The form is:
\frac{a}{b} outputs $\displaystyle \frac{a}{b}$
However you have demonstrated proficiency in Latex beyond this basic command so I would think you know how to use it. If that is the case, which it probably is, please put spaces inbetween the pairs of problems to avoid confusion. But since you will only be posting one problem per thread now, that won't be a problem