Evaluate the following integrals:

We will use basic formula : (a + b)² = a² + b² + 2ab

Or, a² + b² = (a + b)² -2ab

Here,

=

Applying above formula, we get

=

=

Hence, =

Separate the numerator terms,

= { add and subtract 2 to the second term)

= { }

=

= { since }

=