latex large division sign in a math formula [closed]

I found the answer I was looking for. The thing to use here is the construct of

\left \middle \right

For example, in this case, two possible solutions are:

$\left( {\frac{a_1}{a_2}} \middle/ {\frac{b_1}{b_2}} \right) $

Or, in case the brackets are not necessary:

$\left. {\frac{a_1}{a_2}} \middle/ {\frac{b_1}{b_2}} \right. $

Another option is to use \dfrac instead of \frac, which makes the whole fraction larger and hence more readable.

And no, I don't know if there is an option to get something in between \frac and \dfrac, sorry.

A possible soluttion that requires tweaking, but is very flexible is to use one of \big, \Big, \bigg,\Bigg in front of your division sign - these will make it progressively larger. For your formula, I think

  $\frac{a_1}{a_2} \Big/ \frac{b_1}{b_2}$

looks nicer than \middle\ which is automatically sized and IMHO is a bit too large.