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Math Help - Determining Quadrants of Logarithmic Function

  1. #1
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    Determining Quadrants of Logarithmic Function

    How can I determine what quadrants y = log_4(x) lies in?

    I know that this is equivalent to 4^y = x but is there a way I can put that into terms of y so I can plug it into the graphing calculator?

    Thanks!
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  2. #2
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    e^(i*pi)'s Avatar
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    Why not use the change of base rule?

    y = \dfrac{\log_e(x)}{\log_e(4)}
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  3. #3
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    Quote Originally Posted by mathguy20 View Post
    How can I determine what quadrants y = log_4(x) lies in?

    I know that this is equivalent to 4^y = x but is there a way I can put that into terms of y so I can plug it into the graphing calculator?

    Thanks!
    y = \log_b{x} has domain x > 0 and a range of all real numbers ... what quadrants would that be?


    for graphing purposes, note the change of base formula ...

    if y = \log_b{x} , then y = \frac{\log(x)}{\log(b)}

    ... where log is base 10 or base e (your choice on the calculator)

    also, note that the new operating system for the TI-84 will graph logs for any base.
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  4. #4
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    Thanks for the help -- I understand it now.

    And I just updated the OS on my TI-84 as well. Thanks for letting me know about that!
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