Jerry started doing sit-ups everyday. The first day he did 14 sit-ups. Everyday after that he did 4 more sit-ups than he had done the previo

Question

Jerry started doing sit-ups everyday. The first day he did 14 sit-ups. Everyday after that he did 4 more sit-ups than he had done the previous day. Today jerry did 22 sit-ups . Write an equation that could be solved to find the number of days jerry has been doing sit-ups , not counting the first day .

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Amara 1 week 2021-10-05T19:29:15+00:00 1 Answer 0

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    2021-10-05T19:31:09+00:00

    Answer:

    2 days

    Step-by-step explanation:

    The first day Jerry did 14 sit-ups, so the first term of arithmetic sequence is

    a_1=14

    Everyday after that he did 4 more sit-ups than he had done the previous day, then the common differentce is

    d=4

    Today Jerry did 22 sit-ups, hence

    a_n=22

    Use formula for nth term of arithmetic sequence:

    a_n=a_1+(n-1)d

    So

    22=14+(n-1)\cdot 4\\ \\22=14+4n-4\\ \\22=4n+10\\ \\4n=22-10\\ \\4n=12\\ \\n=3

    If not counting the first day, Jerry needs 2 days

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