The 4th term of a G.P. is 16, and the 7th term is 128. Its first term is ______.

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The 4th term of a G.P. is 16, and the 7th term is 128. Its first term is 2. Explanation: 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) = $\frac{16}{128}$ => 1/r^3 = $\frac{1}{8}$ => r = 2 ar^3 = 16 a xx 2^3 = 16 a x 8 = 16 a = 2

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