To simplify the square root of 63, we can find the largest perfect square that is a factor of 63, which is 9. We can rewrite √63 as √(9*7). Using the property of square roots, this can be further simplified as √9 * √7, or 3√7. So, the irrational square root √63 can be rewritten as the product of 3 and the irrational square root √7, in simplest form.
