Step-by-step explanation:
No, the LaTeX that the app uses starts and ends with the [ tex ] and [/ tex ] tags (without the spaces). In (1), simply remove the \latex tag and the integral will appear in embedded form:
[tex] \int_a^b f(x)\, dx[/tex]
This is meant to maintain the line spacing. If you want show the full size of the integral (or in display mode), add the \displaystyle tag after the [ tex ] like this
[ tex ]\displaystyle \int_a^b f(x)\, dx[/ tex ]
and the integral will look like this
[tex]\displaystyle \int_a^b f(x)\, dx[/tex]
after removing the spaces in the [tex] tag. This works also for sums and product of a series and limits.