Partial Fractions are used to turn functions that cannot be integrated into simple fractions that can.

When the denominator is linear the integration will use logarithms.

When the denominator is a quadratic, you may still be able to use logarithms, but probably will need to use a trigonometric integration rule (usually studied in Further Maths, so check with your teacher if you need to know about this).

By rewriting a function as partial fractions, we are able to make approximations to the value of the function using the binomial expansion.