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Math Help - Discrete Maths question

  1. #1
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    Arrow Discrete Maths question

    What is the approximate value of c which minimises |a_100|?

    Where a_n = (8+c)*2^n - (7+c)*3^n

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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by DaRush19 View Post
    What is the approximate value of c which minimises |a_100|?

    Where a_n = (8+c)*2^n - (7+c)*3^n

    Thank you for helping out!
    |a_{100}| is minimised when (8+c)\times 2^n=(7+c) \times 3^c when it is zero. Which is equivalent to:

    (8+c)=(7+c)(3/2)^{100}

    now rearrange:

     <br />
c=\frac{8-7(3/2)^{100}}{(3/2)^{100}-1}\approx -7<br />

    CB
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