the sum of the first n terms of a sequence is 20 – 10 / 2 ^ n – 1 find the sum of the first five terms​

Question

the sum of the first n terms of a sequence is 20 – 10 / 2 ^ n – 1 find the sum of the first five terms​

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Thanh Thu 3 years 2021-08-01T22:18:56+00:00 1 Answers 34 views 0

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  1. mit
    0
    2021-08-01T22:20:44+00:00
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    Answer:

    S_5=\dfrac{170}{9}

    Step-by-step explanation:

    Given that,

    The sum of first n term of a sequence isS_n=20-\dfrac{10}{2n-1}

    We need to find the sum of the first 5 terms.

    Put n = 5,

    S_5=20-\dfrac{10}{2(5)-1}\\\\=20-\dfrac{10}{10-1}\\\\=20-\dfrac{10}{9}\\\\=\dfrac{170}{9}

    So, the sum of first 5 terms is equal to \dfrac{170}{9}.

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