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in a certain geometric sequence, the third term is 8 and the sixth term is 125. what is the first term?

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  1. ar^2 = 8
    ar^5 = 125

    divide the 2nd by the 1st ....
    r^3 = 128/8
    r = 5/2

    back into the first
    a(25/4) = 8
    etc.

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    posted by Reiny

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