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Math Help - Power Functions Help

  1. #1
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    Power Functions Help

    Hey I'm having trouble with trying to figure these two problems out:


    Let f(x) = cx^3.31. How do the function values f(3.6) and f(5.5) compare?


    Let f(x) = cx^4.2 and suppose that f(4) = 18. Find the value of c.


    I've tried plugging them all in and subtracting but i can't seem to figure it out
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  2. #2
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    Quote Originally Posted by MrOoh View Post
    Hey I'm having trouble with trying to figure these two problems out:


    Let f(x) = cx^3.31. How do the function values f(3.6) and f(5.5) compare?


    Let f(x) = cx^4.2 and suppose that f(4) = 18. Find the value of c.


    I've tried plugging them all in and subtracting but i can't seem to figure it out

    1. to compare the two values, divide f(5.5) by f(3.6)

    2. 18 = c \cdot 4^{4.2} ... solve for c
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  3. #3
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    Figured out #1

    5.3^3.27 / 3.4^3.27

    For #2 I get .05 but it's incorrect;

    18 = c4^4.2
    18 = c337.79
    .053 = c
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  4. #4
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    Quote Originally Posted by MrOoh View Post
    Figured out #1

    5.3^3.27 / 3.4^3.27

    For #2 I get .05 but it's incorrect;

    18 = c4^4.2
    18 = c337.79
    .053 = c
    how do you know it's incorrect?
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  5. #5
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    Quote Originally Posted by skeeter View Post
    how do you know it's incorrect?


    I plugged it in as you said the first time and I thought i was doing something wrong- The webApp is WebAssign; .053 == .05
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  6. #6
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    the value of c is correct.
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  7. #7
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    Interesting. I will contact my professor about this. Thanks so much for your help, I really do appreciate it
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