## Algebra 1

$315 \sqrt 2$
$(-5 \sqrt 21) \times (-3 \sqrt 42)$ We multiply the constants 5 and 3. We multiply the numbers inside the square root. $(-5)(-3) (\sqrt (21 \times 42))$ $15 \sqrt 882$ 882 has the factors of $49 \times 18$. $15 \sqrt (49 \times 18)$ 49 is a perfect square. Square root of 49 is 7. Because 7 x 7 = 49 $(15)(7) \sqrt 18$ 18 has the factors of $9 \times 2$. $105 \sqrt (9 \times 2)$ 9 is a perfect square. Square root of 9 is 3. Because 3 x 3 = 9 $(105)(3) \sqrt 2$ $315 \sqrt 2$