Approximate ∫abf(x)dx≈h∑i=1nf(xi−1+xi2)\int_a^b f(x) dx \approx h \sum_{i=1}^n f\left(\frac{x_{i-1}+x_i}{2}\right)∫abf(x)dx≈h∑i=1nf(2xi−1+xi).
