Answer
$63 - 9\sqrt {35a} - 7\sqrt {10a} + 5a\sqrt {14}$
Work Step by Step
We can use the FOIL method to distribute the terms. In the FOIL method, we multiply the first terms, the outer terms, the inner terms, and then the last terms:
$(9)(7) - 9\sqrt {35a} - 7\sqrt {10a} + (\sqrt {10a})(\sqrt {35a}$
Multiply to simplify:
$63 - 9\sqrt {35a} - 7\sqrt {10a} + \sqrt {350a^2}$
Rewrite radicands as the product of two factors. One of the factors should be a perfect square so we can take its square root to remove it from under the radical sign:
$63 - 9\sqrt {35a} - 7\sqrt {10a} + \sqrt {25 • 14 • a^2}$
Take the square root of the perfect squares:
$63 - 9\sqrt {35a} - 7\sqrt {10a} + 5a\sqrt {14}$