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maths sequences help

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    I'm in the process of completing my homework and I am struggling to do some of the questions.

    - find the 50th term of the following sequences:

    1. 5, 5√5,25,25√5

    2. 4a,4,4/a,4/a^2

    Any help and explanations would be appreciated
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    (Original post by goldenusername)
    I'm in the process of completing my homework and I am struggling to do some of the questions.

    - find the 50th term of the following sequences:

    1. 5, 5√5,25,25√5

    2. 4a,4,4/a,4/a^2

    Any help and explanations would be appreciated
    1. Common ratio is \sqrt{5}

    2. Common ratio is \frac{1}{a}

    and work from there using your sequence formulae. Just divide u_{n+1} by u_n and similarly down the line in order to be sure that these are indeed common ratios.
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    (Original post by RDKGames)
    1. Common ratio is \sqrt{5}

    2. Common ratio is \frac{1}{a}

    and work from there using your sequence formulae. Just divide u_{n+1} by u_n and similarly down the line in order to be sure that these are indeed common ratios.
    Thank you, and is that the formula for finding the 50th term or the formula for checking the common ratio?
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    (Original post by goldenusername)
    Thank you, and is that the formula for finding the 50th term or the formula for checking the common ratio?
    Think about it. Why would it for the 50th term?? If you divide a term by the one right before it you will get the ratio between the two.
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    They are both geometric progressions.
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    (Original post by RDKGames)
    Think about it. Why would it for the 50th term?? If you divide a term by the one right before it you will get the ratio between the two.
    I already worked out the common ratio for both sequences. Is the formula for finding any terms an=a x r^n-1 ?
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    (Original post by goldenusername)
    I already worked out the common ratio for both sequences. Is the formula for finding any terms an=a x r^n-1 ?
    Should be the formula in your formulae booklet, yes.

    u_n=a \cdot r^{n-1}
 
 
 
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