Question

Find the first term of the geometric series having the following data: Sn = 1022, r = 2 , n = 9.

Answer 1

General formula for a GS is\(S_n =ar^{n-1}\), where \(S_n\) is the value of nth term, a is the frist term, r is the common ratio, n is the number of terms.
Put \(S_n = 1022\) , r=2 and n=9 into the formula.
\[1022 = a(2)^{9-1}\]Solve a.