Celina Davis
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Does anyone know how to do this question? Any help will be greatly appreciated

The sum of the first two terms of a geometric series is 1 and the sum its first four terms is 5. If all of its terms are positive, find the first term and the common ratio.
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RDKGames
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(Original post by Celina Davis)
Does anyone know how to do this question? Any help will be greatly appreciated

The sum of the first two terms of a geometric series is 1 and the sum its first four terms is 5. If all of its terms are positive, find the first term and the common ratio.
Let a be the first term, and r be the common ratio.

Then a + ar = 1 and a+ar+ar^2+ar^3 = 5.

Note that the second one can be rewritten as (a+ar) + r^2(a+ar) = 5
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