geometicExample12 Find the sum of first n terms and the sum of first 5

1.	geometicExample12 Find the sum of first n terms and the sum of first 5 terms of theseries 1t
Answer» Sum of n terms of geometric series 1 + 2/3 + 4/9+..... Sn = a(1-r^n)/(1-r)For given series a = 1, r = 2/3 Then,Sn = 1(1-(2/3)^n)/(1-2/3) = 3(1 - (2/3)^n) Sum of first 5 termsS5 = 3(1 - (2/3)^5) = 3(1 - 32/243) = 3(243-32)/243 = 211/81 Thanks

geometicExample12 Find the sum of first n terms and the sum of first 5 terms of theseries 1t

Answer»

Sum of n terms of geometric series 1 + 2/3 + 4/9+.....

Sn = a(1-r^n)/(1-r)For given series a = 1, r = 2/3

Then,Sn = 1(1-(2/3)^n)/(1-2/3) = 3(1 - (2/3)^n)

Sum of first 5 termsS5 = 3(1 - (2/3)^5) = 3(1 - 32/243) = 3(243-32)/243 = 211/81

Thanks