=====Mathematics 255 - Fall 2012=====

==== Homework ====

**Section 2.10**: 3, 4, 5, 9, 10, 11, 13, 15, 19, 21, 22, 23


For Problem 19: Note that

$\displaystyle{\frac{1}{(s^2+1)^2} = \frac{1}{2}\left(\frac{d}{ds}\left(\frac{s}{s^2+1}\right) + \frac{1}{s^2+1}\right).}$

Or you can use:

$\displaystyle{\frac{1}{(s^2+1)^2} = \frac{1}{(s^2+1)^2} - \frac{s^2}{(s^2+1)^2} + \frac{s^2}{(s^2+1)^2}}$
$\displaystyle{= \frac{1}{(s^2+1)^2} - \frac{s^2}{(s^2+1)^2} + \frac{1}{s^2+1} - \frac{1}{(s^2+1)^2}}$