# Integration by Substitution

In this article, an integration technique called substitution method will be discussed. The basic concept of this method is to change integral problems into simpler forms.
The general form of internal substitution is as follows,

Example 1.
Solve the integral results of ∫ (x2 + 3)10 2x dx

Example 2.
Solve the integral results of ∫ (x4 – x2)3 (8x3 – 4x) dx

Example 3.
Solve the integral results of ∫ cos 4x dx.

Example 4.
Solve the integral results of ∫ sin3 x cos x dx