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the sum of first 3 terms of a G.P is 16 and the sum of the next 3 terms is 128.determine the first term ,the common ratio and the sum to n terms of the G.P
 If a is first term common ratio is r
a + ar + ar² = 16
and
ar³ + ar4 + r5 = 128
= r³ (a + ar + ar² ) = 128
= (16) (r³) = 128
r = 2
substituting we get a (1 + 2 + 2²) = 16
a = 16/7
Sum of n terms = a (rn -1)/(r -1) = (16/7) (2n -1)/(2 -1) = (16/7)(2n -1)


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