if the sum of the first 14 terms of an ap is 175 and its first term is -7 , find the 21st term

Question

if the sum of the first 14 terms of an ap is 175 and its first term is -7 , find the 21st term

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Alexandra 3 weeks 2021-11-07T09:15:28+00:00 2 Answers 0 views 0

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    0
    2021-11-07T09:17:17+00:00

    \huge {\red {ⓐⓝⓢⓦⓔⓡ }}

    Given :

    First term a = -7

    Sum of 1st 14 terms = 175

    To find :

    21st term

    Solution :

    sum of n terms of an AP =

    </strong><strong>\frac{n}{2} (2a + (n - 1)d)

    so sum of 14 terms of an AP will be

     \frac{14}{2} (2\times - 7 + 13d)

    \implies 175 = 7(-14+13d)

     \implies 175 = -98 +91d)

     \implies 175+98 = 91d

     \implies d =273÷91

     \implies d = 3

    Now,

    Now,21st term = a+20d = -7 +20(3) = -7 + 60 = 53

    __________________________

    hope it helps

    mark as BRAINLIEST

    0
    2021-11-07T09:17:22+00:00

    Answer:

    is it 182

    Step-by-step explanation:

    14 term =175

    1 st = -7

    = -7 +175 = 185

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