M201A, F'14: First graded homework
For each question, state the proposition and write a formal proof.
(
4 points.
) If
x
is an integer, then
x
^{2}
- 3
x
+1 is odd.
(
4 points.
) If
x
is an integer, and
x
^{2}
- 2 is odd, then
x
is odd.