Evaluate:
\(\int \frac{1}{\sqrt{x^{2}+81}}\ dx\)
1
\(\frac{1}{9}ln\left ( x+\sqrt{x^{2}+81} \right)+C\)
2
\(\frac{1}{9}ln\left ( x-\sqrt{x^{2}+81} \right)+C\)
3
\(ln\left ( x+\sqrt{x^{2}+81} \right)+C\)
4
\(ln\left ( x-\sqrt{x^{2}+81} \right)+C\)
Evaluate:
\(\int \frac{1}{\sqrt{x^{2}+81}}\ dx\)