Missing } inserted

Question

I don't know where I've went wrong here. It pops up with "missing } inserted" and I'm not entirely sure what is wrong. It is happening after the "or" part of the code. When i have (x'(t))^2 by itself under the square root it works but when I add the y'(t) bit it doesn't. This is within a table btw.

\(\int_{x_1}^{x_2} {\sqrt{1+{(f'(x))}^2}}\,\mathrm{d}x\) or \(\int_{t_1}^{t_2} 
{\sqrt{{({x'(t)})}^{2}+{({y'(t)})}^{2}}\,\mathrm{d}t\)

Answer 1

You're using too many braces and it's easy to forget one.

\documentclass{article}
\usepackage{amsmath}

\newcommand{\diff}{\mathop{}\!\mathrm{d}}

\begin{document}

\(
  \int_{x_1}^{x_2} \sqrt{1+(f'(x))^{2}}\diff x
\)
or
\(
  \int_{t_1}^{t_2} \sqrt{(x'(t))^{2}+(y'(t))^{2}}\diff t
\)

\end{document}

Answer 2

you have a extra grouping here {\sqrt{