I have a fraction in the denominator of another fraction, and I'm trying to put a set of brackets around it. However, I can't seem to get them to size properly. Example below:
Q_1 \left[ \frac{Q_2}{4\pi \left( r_2+\sqrt{ \dfrac{Q_2\gamma A}{4\pi}} \right)^2 } + Q_3 \right]
which comes...