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Homework Help: How solve the instantaneous rate

  1. Feb 28, 2008 #1
    how solve a limit

    do anyone how do you solve a limit how work because im beginning this heres one problom

    y= [tex]\overline{}2x[/tex]
    Last edited: Feb 28, 2008
  2. jcsd
  3. Feb 28, 2008 #2
    [tex]y=\frac{2x}{x+1}[/tex] is this what u wrote?

    And you want to find the instantaneous rate of change, right?

    Any thoughts from your side on how to do it?
    We are not supposed to do your homework!

    EDIT: to find the instantaneous rate of change you need to evaluate the limit
    [tex]lim_{h\rightarrow\ 0}\frac{f(x+h)-f(x)}{h}[/tex] which actually is the derivative of that function! Assuming that this fucntion represents the velocity!
    Last edited: Feb 28, 2008
  4. Feb 28, 2008 #3

    yes it is and yes im trying to find the instantaneous and it is not homework i want to learn how you solve it step by step
    Last edited: Feb 28, 2008
  5. Feb 28, 2008 #4
    Have you given any thoughts so far on how to do it??? SHow us what have u done so far, so someone here might point u on the right direction. People here won't just give you the answer, especially here at the Homework Forum!
  6. Feb 28, 2008 #5

    the truth is im 14 and i want to be the smartest person on earth and want to be physics professor so i figure you have to learn calculus before going into QUANTUM PHYSICS
  7. Feb 28, 2008 #6
    Well, are u trying to find the limit or the instantenaous rate of change? Because i do not see any limits here?? Can you post the whole question first?
  8. Feb 28, 2008 #7
    I do not think quantum physics is taught at high school is it?
    I envy you for trying to deal with these things at this age! well, i must ask you again, are you trying to find some kind of limits, or what? Because you edited your original post, so i do not know what exactly are you looking for! then i might try to point you on the right direction!
    Last edited: Feb 28, 2008
  9. Feb 28, 2008 #8
    in college

    no way its taught in college but you start learning about physics
  10. Feb 28, 2008 #9

    how do you evaluate instantaneous rate of change and where is the derivative
  11. Feb 28, 2008 #10
    Hi there! Welcome aboard! I too admire your enthusiasm. It is hard, though, to tell where to start, especially without knowing your background in mathematics. If you have a strong background in algebra and geometry, that will definitely help.

    I would suggest searching around online first like http://en.wikipedia.org/wiki/Derivative" [Broken] and seeing what you can extrapolate for yourself. Then come on back here to PF and show us exactly where you are having trouble.

    Do you understand what the derivative means? If not, do a little reading in Wiki or elsewhere and come back with questions.

    Hope to hear from you soon!
    Last edited by a moderator: May 3, 2017
  12. Feb 28, 2008 #11

    I Only Know The Power Rule To Find Dervitives But Geometry I Get
  13. Feb 28, 2008 #12
    Google "the quotient rule" and see what you get. Come back with questions.
  14. Feb 28, 2008 #13
    is that how you do it because i Google the quiotent rule but just didn't know what it meant

    \frac{d}{dx}f(x) = f'(x) = \frac{h(x)g'(x) - g(x)h'(x)}{[h(x)]^2}.
  15. Feb 29, 2008 #14
    The deal is that if you really want to learn this material, then you have to start from something that is really elementary, and do things one step at a time! so if you have no idea what a limit is, and what a derivative is, then my advice is buy a book that is really elementary but that will introduce you to some quite important concepts!
  16. Feb 29, 2008 #15
    I'd recommend reading the theory behind derivatives as rate of change, and it's geometric significance. And one more thing, be thorough with the concept of limits (not just some list of formulas), so that you can understand the "first principle" of derivatives and other elementary concepts.

    Here is a link to a complete video series on Calculus by Houston University,


  17. Feb 29, 2008 #16

    i have a book about calculus its called super review calculus all you need to know but its just confusing
  18. Feb 29, 2008 #17
    Unfortunately, we cannot just teach you calculus. We can help you along, but you need to work through a lot of it on your own. You should find a different book to learn from. Like one of the demystified books. Something that explains the concepts. Then you can try to apply them to the specific problems.
  19. Feb 29, 2008 #18
    ok i have on the link on 1 page
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