To rewrite the irrational square root \( \sqrt{63} \) as the product of an integer and another irrational square root, we start by factoring \( 63 \).
We can express \( 63 \) as follows:
\[ 63 = 9 \times 7 \]
Now, we can take the square root of each factor:
\[ \sqrt{63} = \sqrt{9 \times 7} = \sqrt{9} \times \sqrt{7} \]
Since \( \sqrt{9} = 3 \), we have:
\[ \sqrt{63} = 3 \times \sqrt{7} \]
Thus, \( \sqrt{63} \) can be rewritten in simplest form as:
\[ \sqrt{63} = 3\sqrt{7} \]