Equation isn't an equation
File in which the problem appears
Basics of the Monte Carlo method
Problematic sentence
\int p(x)f(x)dx \underbrace{\approx}_\text{xi sampled from p(x)}\frac{1}{N}\sum_i f(x_i) + \mathcal{O}(\frac{1}{\sqrt{N}},. \tag{2}
Correct version
It should be a nice-looking equation but now it's only code (I'm not sure how)