[Tex/LaTex] Double superscript error in fractions

errorssuperscripts

I'm basically new to LaTex and still learning, and while I'm trying to write this fraction:

$\frac{x}{sin({b_{2}})} = \frac{{A_{b}}{B_{a}}}{sin(C’’)}$

I get error: double superscript. I tried putting brackets in diffrent combinations but so far none have worked. Any ideas how can I make it work?

Edit:
When I put into a separate file, like that:

    \documentclass[b5paper,11pt,twoside,titlepage]{article}

\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsfonts}

\begin{document}
$\frac{x}{\sin{b_2}} = \frac{{A_b}{B_a}}{\sin{C’’}}$ \\
\end{document}

it works fine. But in the file I still get an error:

! Double superscript.
<recently read> ^
l.225 ...{b_2}} = \frac{{A_b}{B_a}}{\sin{C’’}}
\)
I treat `x^1^2' essentially like `x^1{}^2'.

And I should add the error appears as if it was in next line to the one with problematic code.

Edit 2:
I repaired it. Apparently I used a fancy version of ' when I was pasting part of my code form source. After putting a normal '' there everything was fine.

Best Answer

The minimal example doesn't show errors, but no prime appears either.

In the second example, you have \usepackage[utf8]{inputenc} and you get the error, together with

LaTeX Warning: Command \textquoteright invalid in math mode

You have to use an undirected quote for getting a prime in math mode.

$\frac{x}{\sin b_2} = \frac{A_bB_a}{\sin C''}$

By the way, you don't need braces after \sin, nor around A_b and B_b.

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