The second example sheet for Math 221 is here: pdf
The third example sheet for Math 221 is here: pdf
The fourth example sheet for Math 221 is here: pdf
The fifth example sheet for Math 221 is here: pdf
The sixth example sheet for Math 221 is here: pdf
The seventh example sheet for Math 221 is here: pdf
The eighth example sheet for Math 221 is here: pdf
The ninth example sheet for Math 221 is here: pdf