The sum of the first "n" terms of series is 2^(n+3) -8.Find the 7th term.

Answer 1

Assuming a geometric series,

Sn = a(r^n-1)/(r-1)
So, since
2^(n+3)-8 = 2^n*2^3 - 8 = 8*2^n-8 = 8(2^n-1)

Looks like a=8 and r=2.
S7 = 8*2^6 = 512