# How do you find the LCD of 49/(s^2-100) , (s+7)/(s^2-8s-20)?

Sep 6, 2016

The LCD is $\left(s - 10\right) \left(s + 10\right) \left(s + 2\right)$.

#### Explanation:

Factor both denominators.

${s}^{2} - 100 = \left(s + 10\right) \left(s - 10\right)$

${s}^{2} - 8 s - 20 = \left(s - 10\right) \left(s + 2\right)$

What do these factorings have in common?

$s - 10$

What don't they have in common?

$s + 10$ and $s + 2$

Hence, the LCD will be $\left(s - 10\right) \left(s + 10\right) \left(s + 2\right)$.

Hopefully this helps!