A community for students. Sign up today!
Here's the question you clicked on:
 0 viewing
 2 years ago
General question about derivative.. When I take my second derivative I usually end up with crazy numbers and I'm asked for the Inflection point
An example of what happens to me is with this function:
x^3/(x^216)
I end up with maybe some x^7 and x^5 at the second derivative and its way too much for me to figure out the inflection point... any help?
 2 years ago
General question about derivative.. When I take my second derivative I usually end up with crazy numbers and I'm asked for the Inflection point An example of what happens to me is with this function: x^3/(x^216) I end up with maybe some x^7 and x^5 at the second derivative and its way too much for me to figure out the inflection point... any help?

This Question is Closed

bear4343
 2 years ago
Best ResponseYou've already chosen the best response.1I have to write this in parts so bear with me. d/dx(x^3/(16+x^2)) = (x^2 (x^248))/(x^216)^2

MarcLeclair
 2 years ago
Best ResponseYou've already chosen the best response.0its okay i got that part its just what comes afterward is insanely long and I can't find the inflection point afterwards

bear4343
 2 years ago
Best ResponseYou've already chosen the best response.1(32 x (x^2+48))/(x^216)^3 is the second derivative

bear4343
 2 years ago
Best ResponseYou've already chosen the best response.1do you get how I got to where I am?

MarcLeclair
 2 years ago
Best ResponseYou've already chosen the best response.0Nope, I don't understand how you simplified it, I used a website to get there.. I keep g etting insane numbers

bear4343
 2 years ago
Best ResponseYou've already chosen the best response.1I used the quotiant rule. This is the way i learned to remember it. low d high minus high d low and down below the low squareds go.

bear4343
 2 years ago
Best ResponseYou've already chosen the best response.1youalsohave to be careful because you also have to do the product rule

MarcLeclair
 2 years ago
Best ResponseYou've already chosen the best response.0well i mean after your first step this is what i got : (x^448x^2)'(x^216)^2(x^448x^2)(x^216)^2 / (x^216)^4 and then on the numerator to find my inflection point at the end i think i had something like 160x^5 somethingx^3... :/

bear4343
 2 years ago
Best ResponseYou've already chosen the best response.1well lets start with an inflection point, the inflection point is where the concavity of the original function changes.

MarcLeclair
 2 years ago
Best ResponseYou've already chosen the best response.0yeah where the second derivative is = 0. But I mean I can't do that i have 3 diferent x :/ especially at such high powers

bear4343
 2 years ago
Best ResponseYou've already chosen the best response.1what i always do in my mind when solving a problem like this I have to imagine what the graph would look like

MarcLeclair
 2 years ago
Best ResponseYou've already chosen the best response.0the problem is that I'm solving the graph at the moment, to me its hard picturing cubic over parabolas, never drew them and I'm new to graph sketching. So when come the time to do the derivative I don't understand how people simpliy that much like you just did

bear4343
 2 years ago
Best ResponseYou've already chosen the best response.1I can quickly tell the only point where f" i think also by looking at where you can make it zero because I Know it has to pass through zero when I get the second derivative. If youtake the second derivative and set it equal to zero you can then find the inflection point

MarcLeclair
 2 years ago
Best ResponseYou've already chosen the best response.0yeah but with what I get its nearly impossible to get to it because i get this: (x^448x^2)'(x^216)^2(x^448x^2)(x^216)^2' which then turns out as (4x^396x)(x^216)  2(x^448x^2)(2x) / (x^216)^3 and the numerator becomes crazy 4x^564x^396x^31536x  2(2x^496x^3) and I have so many leftovers that I can't deal with

MarcLeclair
 2 years ago
Best ResponseYou've already chosen the best response.0oh nevermidn i got it you simplified it, I'm really stupid today x.x thanks a lot bear :)

bear4343
 2 years ago
Best ResponseYou've already chosen the best response.1Just copied from above {d/dx(x^3/(16+x^2)) = (x^2 (x^248))/(x^216)^2 I simplified it on the right once i found the derivative because i don't want to have to deal with the bigger numbers.

bear4343
 2 years ago
Best ResponseYou've already chosen the best response.1Your welcome, if you need any help in the future with calculus let me know.
Ask your own question
Ask a QuestionFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.