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Question
The 4th term of a G.P. is 16 and the 7th term is 128. Find the first term and common ratio of the series
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Solution
The 4th term of a G.P. = 16
`=> ar^(4-1) = 16`
7th term of G.P. = 128
`=> ar^(7-1) = 128`
so, `(ar^3)/(ar^6) = 16/128`
`=> 1/r^3 = 1/8`
=> r = 2
`ar^3 = 16`
`a xx 2^3 = 16`
a x 8 = 16
a = 2
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