Question:
Show that the following statement is true by the method of contrapositive.
$p:$ If $x$ is an integer and $x^{2}$ is even, then $x$ is also even.
Solution:
$p$ : If $x$ is an integer and $x^{2}$ is even, then $x$ is also even.
Let $q: x$ is an integer and $x^{2}$ is even.
$r . x$ is even.
To prove that p is true by contrapositive method, we assume that r is false, and prove that q is also false.
Let x is not even.
To prove that $q$ is false, it has to be proved that $x$ is not an integer or $x^{2}$ is not even.
$x$ is not even implies that $x^{2}$ is also not even.
Therefore, statement q is false.
Thus, the given statement p is true.