Question

Calculați integrală de la 1 la 9 din
$\frac{1}{ \sqrt{ {x}^{2} } }$
dx.

Answer 1

$\displaystyle \mathtt{\int\limits_1^9 \frac{1}{ \sqrt{x^2}}dx =\int\limits_1^9 \frac{1}{x}dx =ln|x|\Bigg|_1^9=ln|9|-ln|1|=ln~9-0=ln~9}$