# Thread: Major Math Graphing Assignment

1. ## Major Math Graphing Assignment

I have to graph this function as part of my math assignment for calculus.

f(x) = x2 (supposed to be x squared) - 2x - 15
x + 3

** it's x squared minus 2x minus 15 all over x+3

i know that it is a straight line with a whole in it at x= -3. However, i just want to make sure i have all the steps correct in coming up with this answer. And even though it's a straight line, i need to determine f'(x) and f''(x) to find critical points and intervals of concavity and inflection point.

Any help at all would be much appreciated.. thank-you very much

2. Originally Posted by jmailloux
I have to graph this function as part of my math assignment for calculus.

f(x) = x2 (supposed to be x squared) - 2x - 15
x + 3

** it's x squared minus 2x minus 15 all over x+3

i know that it is a straight line with a hole in it at x= -3. However, i just want to make sure i have all the steps correct in coming up with this answer. And even though it's a straight line, i need to determine f'(x) and f''(x) to find critical points and intervals of concavity and inflection point.

Any help at all would be much appreciated.. thank-you very much
$\displaystyle f(x) = \frac{x^2 - 2x - 15}{x + 3}$

$\displaystyle f(x) = \frac{(x + 3)(x - 5)}{x + 3}$

So
$\displaystyle f(x) = x - 5$, $\displaystyle x \neq -3$.

So now take your derivatives using this form. You CAN take the derivatives using the original form, but it'll get messy quickly.

-Dan