Hey guys, I just have quick question:
How does $\displaystyle \frac{\sqrt{9x^2+x}}{x} = \sqrt{9+1/x}$ knowing that $\displaystyle \sqrt{x^2} = x$
big thanks.
Assuming that $\displaystyle \displaystyle x \geq 0$, then $\displaystyle \displaystyle \sqrt{x^2} = x$.
Since $\displaystyle \displaystyle \frac{\sqrt{9x^2 + x}}{x} = \frac{\sqrt{9x^2 + x}}{\sqrt{x^2}}$
$\displaystyle \displaystyle = \sqrt{\frac{9x^2 + x}{x^2}}$.
Go from here.