I tried to adapt this part of a template:

y=&ax+b&&\text{(definition of a straight line)}\nonumber\\
  &f'(a)x+b&&\text{(definition of the derivative)}\nonumber\\
  &f'(a)x+f(a)-f'(a)a&&\text{(we know that the line intersects $f$ at $(a,f(a))$}\nonumber

By writing:

$c^j_{0}$ = &($x_{j}$-30)^4($x_{j}$-32)^4&&\text{(si $x_{j}$ \in [30,32])}\nonumber\\

But this error message appears no matter what I try do to to fix it:

Missing } inserted.
<inserted text> 
l.30 \end{align}
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    – Werner
    Commented Dec 24, 2016 at 5:17

1 Answer 1


You are using $ to go into math mode when LaTeX is already in math mode because the align environment is usually maths. You still need to go into math mode inside your \text bit though, although I expect there's a better way to do it.

Reproducible example:


c^j_{0} = &(x_{j}-30)^4(x_{j}-32)^4&&\text{(si $x_{j} \in [30,32]$)}\nonumber\\


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