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krypton

y=lmx->inf (xe^x)/(x^2+2x-1) use l hopitals rule

  • one year ago
  • one year ago

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  1. zepdrix
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    Before using L'Hopital's Rule, verify that the limit is of an indeterminate form. This limit appears to be of the indeterminate form: \[\frac{ \infty }{ \infty }\] So we can apply L'Hopital's Rule. Do you need help applying the rule? :)

    • one year ago
  2. krypton
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    yeah i do pls

    • one year ago
  3. krypton
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    beacuse after applying the rule, i syill got inf/inf

    • one year ago
  4. zepdrix
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    |dw:1349037732010:dw| Still getting Inf/Inf? Good that is still an indeterminate form, which means you can apply L'Hop again! :)

    • one year ago
  5. krypton
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    so how do i apply it again?

    • one year ago
  6. krypton
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    after the 1st derivative, i got e^x(1+x)/(2x+2) then i plugged in inf and got inf/inf

    • one year ago
  7. zepdrix
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    |dw:1349037925108:dw| Yah you need to apply L'Hop from that spot again :)

    • one year ago
  8. zepdrix
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    The important thing to remember is that - You can only apply L'Hop rule a second time (or even third time, etc.. ) if it is STILL of an indeterminate form after the first application of L'Hop. Still confused? :O

    • one year ago
  9. krypton
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    yeah i now understand thanks alot :)

    • one year ago
  10. zepdrix
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    yay \c:/

    • one year ago
  11. krypton
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    hey so the answer will be?

    • one year ago
  12. krypton
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    infinity?

    • one year ago
  13. zepdrix
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    So it looks like it simplifies to:\[\frac{ \infty }{ 2 }\] Which, yes is simply Infinity. Good job! :)

    • one year ago
  14. krypton
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    hi i need a bit help with one other scenario as i wasnt in the class when the whole topic was thought how about this y=limx->0^+ x^2x

    • one year ago
  15. krypton
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    thats x approches 0 from the right

    • one year ago
  16. zepdrix
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    |dw:1349039331256:dw|

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  17. zepdrix
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    |dw:1349039504362:dw|

    • one year ago
  18. zepdrix
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    |dw:1349039633140:dw|

    • one year ago
  19. zepdrix
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    |dw:1349039718975:dw|

    • one year ago
  20. zepdrix
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    |dw:1349039844810:dw|

    • one year ago
  21. zepdrix
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    |dw:1349039949728:dw| Get stuck on any part of that? I tried to be detailed, since you missed the concept in class D': It's a little tricky.

    • one year ago
  22. krypton
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    1?

    • one year ago
  23. zepdrix
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    Yay \:D/

    • one year ago
  24. krypton
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    does this math change if the say x approaches 0 from the left??

    • one year ago
  25. krypton
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    0^-

    • one year ago
  26. zepdrix
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    Yes. The reason they made that distinction, is because the Natural log is only defined for values greater than 0. If we were approaching 0 from the left, it wouldn't make any sense, because that value isn't in the domain of lnx. So we are forced to approach from positive values! :)

    • one year ago
  27. zepdrix
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    |dw:1349040248054:dw|

    • one year ago
  28. krypton
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    oh! ok thanks alot for your help.so this as far as l'hopitals rule goes, no other thing? if is inderterminant u keep using the rule and taking the 2nd derivate

    • one year ago
  29. zepdrix
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    Yes repeat as often as you are able to. :) Important note: You need the CORRECT indeterminate form to apply L'Hop. If I remember correctly you need one of these two forms:\[\frac{ 0 }{ 0 },\frac{ \infty }{ \infty }\] In this problem we just did, we had the indeterminate form: \[\infty*0\]So we had to move things around before we could apply L'Hop :)

    • one year ago
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