Re: displaymath negli array

`\[
\begin{array}{ll}
\hline\displaystyle \dd x x^\alpha=\alpha x^{\alpha-1} &\displaystyle
\int x^\alpha dx=\frac{x^{\alpha+1}}{\alpha+1}+c \\
\hline\displaystyle \dd x e^x=e^x &\displaystyle \int e^xdx=e^x+c \\
\hline\displaystyle \dd x \sin x=\cos x &\displaystyle \int\sin xdx=-\cos x+c \\
\hline\displaystyle \dd x \cos x=-\sin x &\displaystyle \int\cos xdx=\sin x+c \\
\hline
\end{array}
\]`