1.$\displaystyle \int\frac{sinx}{x}dx$
2.$\displaystyle \int_{-00}^{00} (cosx)e^{-x^{2}/2}dx$
You can not solve this integrals in terms of elementary function.
This well-known integral is used in electrical engineering.
See:
integrate sin(x)/x - Wolfram|Alpha
Hi. It's a suggestion to treat "special functions" like antiderivatives of integrals that can't be expressed in simple terms, in the same way that you treat $\displaystyle \sin(x)$ so if I have $\displaystyle \int \cos(x)dx$ you say "hey, that's easy, it's $\displaystyle \sin(x)$. So hey, $\displaystyle \int \frac{sin x}{x}$ is easy. It's . . .
Also, for that second we did that one here:
http://www.mathhelpforum.com/math-he...x-e-x-2-a.html