This may be a limitation of how the filter tex works, generating the image per the equation/formula being used.

If the notation is long, the generated image will overflow the HTML elements.

Replication:

1. Create a quiz.
2. Add an essay question and attempt or preview it.
3. Use the following as an answer:
   $$ x\ =\ \frac{\sqrt{144}}{2}\ \times\ (y\ +\ 12) x\ =\ \frac{\sqrt{144}}{2}\ \times\ (y\ +\ 12) x\ =\ \frac{\sqrt{144}}{2}\ \times\ (y\ +\ 12) x\ =\ \frac{\sqrt{144}}{2}\ \times\ (y\ +\ 12) x\ =\ \frac{\sqrt{144}}{2}\ \times\ (y\ +\ 12)$$

RESULT: The generated formula / image is overflowing.