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Question
Find:
the ninth term of the G.P. 1, 4, 16, 64, ...
Solution
Here,
\[\text { First term, } a = 1 \]
\[\text { Common ratio }, r = \frac{a_2}{a_1} = \frac{4}{1} = 4\]
\[ \therefore 9th\text { term } = a_9 = a r^{(9 - 1)} = 1(4 )^8 = 4^8 = 65536\]
\[\text { Thus, the 9th term of the given GP is } 65536 .\]
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