These transformations help simplify complex integrals by changing variables. Substitution is a powerful method for evaluating integrals involving algebraic, trigonometric, exponential, or logarithmic expressions.
\[ \int F(ax + b) \, dx = \frac{1}{a} \int F(u) \, du, \quad u = ax + b \]
\[ \int F(\sqrt{ax + b}) \, dx = \frac{2}{a} \int u F(u) \, du, \quad u = \sqrt{ax + b} \]