13. Prove or disprove each of the following statements:
- If \(n\) is an integer, then \(3 n ^ { 2 } - 11 n + 13\) is a prime number.
- If \(x\) is a real number, then \(x ^ { 2 } - 8 x + 17\) is positive.
- If \(p\) and \(q\) are irrational numbers, then \(p q\) is irrational.
[0pt]
[BLANK PAGE]