How do you write the explicit formula for the following geometric sequence: -0.1, 0.03, -0.009, 0.0027, -0.00081, ...?

1 Answer
Shwetank Mauria
Sep 13, 2016

n^(th) term of given geometric series is (-0.1)xx(-0.3)^(n-1)

Explanation:

In the given geometric series

{-0.1,0.03,-0.009,0.0027,-0.00081,......},

the first term is -0.1 and common ratio is 0.03/(-0.1)=(-0.009)/0.03=0.0027/(-0.009)=(-0.00081)/0.0027=-0.3

As the n^(th) term of a geometric series whose first term is a and common ratio is r is axxr^(n-1)

Hence n^(th) term of given geometric series is

(-0.1)xx(-0.3)^(n-1)

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