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Calle87

  • 3 years ago

Need some help identifying the increase intervals of the graph of xtanx

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  1. Calle87
    • 3 years ago
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    |dw:1349987981581:dw|

  2. Venomblast
    • 3 years ago
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    is this in radian?

  3. Calle87
    • 3 years ago
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    i know this is a even function about the y axis, and the domain and asymptotes are pi/2,-pi/2

  4. Calle87
    • 3 years ago
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    just wondering how to show the intervals of increase and decrease

  5. Venomblast
    • 3 years ago
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    so -90 degrees <x<90 degrees

  6. Calle87
    • 3 years ago
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    usually i take f'x and solve for 0

  7. Venomblast
    • 3 years ago
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    i see

  8. Venomblast
    • 3 years ago
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    i see no 0. is this is an equation?

  9. Calle87
    • 3 years ago
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    f'x=tanx+xsec^2x

  10. Calle87
    • 3 years ago
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    @zepdrix hey do you think you could explain how they designate zero as a critical point?

  11. Calle87
    • 3 years ago
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    |dw:1349988599121:dw|

  12. Calle87
    • 3 years ago
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    should i just know that, from the x and y intercepts and the even symetry? and a basic knowledge of the tanx graph?

  13. Calle87
    • 3 years ago
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    because when i set my derivative = 0 i have problems

  14. zepdrix
    • 3 years ago
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    |dw:1349988578994:dw| Hmm yah this derivative does seem to be putting up a fight :\ Hmmmmm

  15. Calle87
    • 3 years ago
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    i tried changing everything to sines and cosines and still a mess

  16. zepdrix
    • 3 years ago
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    |dw:1349988855254:dw| Ah good call, I think that's how you find it! :) The top is a big mess, yes. But the bottom I think you can solve for a critical point.

  17. Calle87
    • 3 years ago
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    |dw:1349988866328:dw|

  18. Venomblast
    • 3 years ago
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    get the common denominator. so multiply cosx on the 1st term

  19. Calle87
    • 3 years ago
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    thats it zep!!!!!!!!

  20. Venomblast
    • 3 years ago
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    ? zep?

  21. Calle87
    • 3 years ago
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    @zepdrix :D

  22. Venomblast
    • 3 years ago
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    i guess he/she got it from here

  23. zepdrix
    • 3 years ago
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    |dw:1349989056773:dw|

  24. Calle87
    • 3 years ago
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    i think the top should be ignored

  25. Calle87
    • 3 years ago
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    the book doesent have a mention of it

  26. Calle87
    • 3 years ago
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    neither does the graph

  27. Calle87
    • 3 years ago
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    the only root is 0

  28. Calle87
    • 3 years ago
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    http://www.wolframalpha.com/input/?i=graph+xtanx

  29. Calle87
    • 3 years ago
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    maybe it would matter if the interval was larger than -pi/2,pi/2

  30. zepdrix
    • 3 years ago
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    yah fair enough c:

  31. zepdrix
    • 3 years ago
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    Hmmm wait what was I saying? cos x = 0 Hmm that should give you x = pi/2 right? why did i say it was x = 0? Hmmmmmmmmmmmmmmmmm Now I'm back to being confused about where the 0 critical point is coming from :D lol

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