A community for students. Sign up today!
Here's the question you clicked on:
 0 viewing
 2 years ago
I can only find derivative for x>0 , but I don't know why (according to wolfram).
 2 years ago
I can only find derivative for x>0 , but I don't know why (according to wolfram).

This Question is Closed

TomLikesPhysics
 2 years ago
Best ResponseYou've already chosen the best response.0mom I need to attach the equations

TomLikesPhysics
 2 years ago
Best ResponseYou've already chosen the best response.0My f`is apparently only true for x>0 and I have no clue where I make that assumption in my differentiation.

Zekarias
 2 years ago
Best ResponseYou've already chosen the best response.0Your f' is defined only for R\{6^{0.5), 6^(0.5)}, actually

TuringTest
 2 years ago
Best ResponseYou've already chosen the best response.0how do you figure @Zekarias

TuringTest
 2 years ago
Best ResponseYou've already chosen the best response.0f' is not defined at +/6^(0.5), but it is for all other points as far as I see

TuringTest
 2 years ago
Best ResponseYou've already chosen the best response.0I do see one problem which is that for 6^(0.5)<x0 the slope should be negative, but the derivative is positive

TuringTest
 2 years ago
Best ResponseYou've already chosen the best response.06^(0.5)<x<0 I meant

TuringTest
 2 years ago
Best ResponseYou've already chosen the best response.0http://www.wolframalpha.com/input/?i=plot%20y%3D(x%5E26)%5E(2%2F3)&t=crmtb01 you can see the slope is negative for 6^(1/2)<x<0, but the derivative would be positive as you have it

TomLikesPhysics
 2 years ago
Best ResponseYou've already chosen the best response.0ok, so how should I take the derivative then? Without rewriting it and using the chainrule over and over?

TuringTest
 2 years ago
Best ResponseYou've already chosen the best response.0that I'm not so sure about. I'm thinking on it.

TuringTest
 2 years ago
Best ResponseYou've already chosen the best response.0@amistre64 any ideas here?

amistre64
 2 years ago
Best ResponseYou've already chosen the best response.2the derivative on the attachment looks fine; im not sure what the question is tho

TuringTest
 2 years ago
Best ResponseYou've already chosen the best response.0http://www.wolframalpha.com/input/?i=derivative+of+y%3D%28x%5E26%29%5E%282%2F3%29 true I don't see wolf giving the condition that x>0

TuringTest
 2 years ago
Best ResponseYou've already chosen the best response.0but what about the point I brought up? f' for 6^(1/2)<x<0 should be negative, but it's positive

amistre64
 2 years ago
Best ResponseYou've already chosen the best response.2http://www.wolframalpha.com/input/?i=derivative+cbrt%28%28x%5E26%29%5E2%29 i think this has more intricate workings than we think

amistre64
 2 years ago
Best ResponseYou've already chosen the best response.2\[u=(x^26)^2~:~u'=4x(x^26)\] \[D[u^{1/3}]=\frac{u^{1/3}}{3}u'\] \[D[u^{1/3}]=\frac{4x(x^26)}{3((x^26)^2)^{1/3}}\]

amistre64
 2 years ago
Best ResponseYou've already chosen the best response.2at 1\[\frac{*}{+}=+\]

TuringTest
 2 years ago
Best ResponseYou've already chosen the best response.0but that should not be if you look at the graph http://www.wolframalpha.com/input/?i=plot%20y%3D(x%5E26)%5E(2%2F3)&t=crmtb01 should be f'<0 at x=1

amistre64
 2 years ago
Best ResponseYou've already chosen the best response.2notice that the function\[\sqrt[3]{((x^26)^2)}\ne \left(\sqrt[3]{(x^26)}\right)^2\]at all points http://www.wolframalpha.com/input/?i=%28%28x%5E26%29%5E2%29%5E%281%2F3%29++%28%28x%5E26%29%5E%281%2F3%29%29%5E2

amistre64
 2 years ago
Best ResponseYou've already chosen the best response.2the subtlties are in how we are not using the "correct" use of a derivative

amistre64
 2 years ago
Best ResponseYou've already chosen the best response.2the way we are used to working with exponents seems to be a misuse of notation and doesnt express the full nature of the problem http://www.wolframalpha.com/input/?i=y%3D%28%28x%5E26%29%5E2%29%5E%281%2F3%29%2C+y%3D+%28%28x%5E26%29%5E%281%2F3%29%29%5E2

TomLikesPhysics
 2 years ago
Best ResponseYou've already chosen the best response.0So I should not rewrite the equation and just use the chainrule multiple times then to end up with the same answer as wolfram does?

amistre64
 2 years ago
Best ResponseYou've already chosen the best response.2correct, I would simplify it by making a substitution; then replacing those values in the end

TomLikesPhysics
 2 years ago
Best ResponseYou've already chosen the best response.0k, thx. I will try that now.

TomLikesPhysics
 2 years ago
Best ResponseYou've already chosen the best response.0Damn. That went well and it was pretty quick and easy too. So the first attempt did not work because I messed the exponents up?
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.