The Square Root Trick
When you run into the indeterminate form(Indeterminate Forms and Dealing with Them) $\frac{0}{0}$ while taking the limit of a function $f$ and either the numerator or denominator of the function is in the form $a + b\sqrt{c}$, you can just multiply both sides of the fraction with $a-b\sqrt{c}$ and then calculate the limit from there.
HOT TIP! If you run into the case where both sides are of the form above, you can do the method twice, once for the numerator and once for the denominator, this should get you to the answer in most cases.