A geometric progression has common ratio = 3 and last term = 486. If the sum of its terms is 728; find its first term.
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Question

A geometric progression has common ratio = 3 and last term = 486. If the sum of its terms is 728; find its first term.

KnowledgeBoat · Accepted Answer

Let n^th term be the last term. ⇒ ar^{n - 1} = 486 ⇒ a(3)^{n - 1} = 486 ⇒ a.3ⁿ.3^-1 = 486 ⇒ Since, r 1 Hence, first term = 2.

Mathematics