Integration durch Substitution

∫abf(g(x))⋅g′(x)dx=∫g(a)g(b)f(y)dy\begin{equation} \int_{a}^{b} f(g(x)) \cdot g^{\prime}(x) \mathrm{d} x=\int_{g(a)}^{g(b)} f(y) \mathrm{d} y \end{equation}