Thinking Mathematically (6th Edition)

$\sqrt3 - \sqrt3 = 0$ $\sqrt3$ is irrational, but 0 is not.
Irrational numbers are not closed with respect to subtraction, as can be seen in the example below: $\sqrt3$ is an irrational number. However, $\sqrt3 - \sqrt3 = 0$, which is not an irrational number.