Question

Preform the indicated operation:
4 over a^2+12a+27 + 5 over a^2+10a+21

What are the values that would be excluded from the domain?

a. 9, -3 and -7
b. -9, 3, and -7
c. -9,-3, and 7
d. -9, -3, and -7

Answer 1

equation attatched

Answer 2

I think any value that results in a denominator of zero for either of the terms should be excluded. Any of the positive numbers result in non-zero denominators, but all three of the negative numbers result in at least one of the denominators being zero.

I would circle d.

Answer 3

These factor to
\[\frac{4}{(a+3)(a+9)}+\frac{5}{(a+7)(a+3)}\]The values that make the numerator zero are, like MathDrills said, -9, -3, and -7.