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Can you find the next two terms?

1, 5, 17, 53, 161, ..., ...,

4 Answers

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  • pc-5
    Lv 6
    9 years ago
    Favorite Answer

    The general term for this sequence is 2*3^n - 1.

    So t5 = 2*3^5 - 1 = 2*243 - 1 = 485.

    And t6 = 2*3^6 - 1 = 2*729 - 1 = 1457

  • brainy
    Lv 4
    9 years ago

    T 1 = 1

    T 2 = 5 = 3 x 1 + 2 = 3 + 2 = 5 = 3 x T1 + 2

    T 3 = 17 = 3 x 5 + 2 = 15 + 2 = 17 = 3 x T2 + 2

    T 4 = 53 = 3 x 17 + 2 = 51 + 2 = 53 = 3 x T3 + 2

    T 5 = 161 = 3 x 53 + 2 = 159 + 2 = 161 = 3 x T4 + 2

    T 6 = 161 = 3 x 161+ 2 = 483 + 2 = 485 = 3 x T5 + 2

    T 7 = 161 = 3 x 485 + 2 = 1455+ 2 = 1457 = 3 x T6 + 2

    T 8 = 161 = 3 x 1457+ 2 = 4371 + 2 = 4373 = 3 x T7 + 2

    The Formula for the series Tn = { 3 x T(n-1) } + 2

    Where Tn in the n th term and T (n-1) is the previous term of the series

    So by using this formula you can find any term in this series, but you must work for each term

    If you or your frind is competent in EXCEL , you can apply the formula and see how the series is going up

    For example by excel the series is this one

    1

    5

    17

    53

    161

    485

    1457

    4373

    13121

    39365

    118097

    354293

    1062881

    3188645

    9565937

    28697813

    86093441

    258280325

    774840977

    2324522933

    6973568801

    Source(s): OWN & EXCEL
  • ?
    Lv 7
    9 years ago

    The given terms increase by 4, 12, 36, 108...

    ie the increase is multiplied by 3 each time.

    The next increases are 3*108 = 324 and 3*324 = 972

    161 + 324 = 485 <<<

    485 + 972 = 1457<<<

  • Anonymous
    9 years ago

    3x1 = 3 [+2] = 5

    3x5 = 15 [+2] = 17

    3x17 = 51 [+2] = 53

    3x53 = 159 [+2] = 161

    3x161 = 483 [+2] = 485

    3x485 = 1455 [+2] = 1457

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