Recall that a rational number is a number that can be written as a fraction $\frac { a } { b }$ where $a$ and $b$ are integers and $b ≠ 0$.

1. In part (a) of problem 11-17 you multiplied two rational numbers and your result was a rational number. Will that always be true? In other words, is the set of rational numbers closed under multiplication? Justify your answer.

   Hint (a):

   Is this answer a rational number?

2. In part (b) of problem 11-17 you divided two rational numbers and your result was a rational number. Are the rational numbers closed under division? Justify your answer.

   Hint (b):

   Use the same method as part (a).