The 3rd term and 9th term of a G.P are 54 and 39,366 respectively.Find the:6th term,sum of the 4th and 7th term and product of 2nd and 5th term?

3 answers

54 r^6 = 39366 ... r^6 = 729 ... looks like the ratio (r) is 3

start with the 3rd term , and keep multiplying by 3

you'll have to divide by 3 to find the 2nd term
the two terms are 6 apart, so
r^6 = 39366/54 = 729
r = ±3
So now you want to find a, and then
a_6 = ar^5
a_4 + a_7 = ar^3(1+r^3)
a_2 * a_5 = a^2 r^5
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