What is the sum of the geometric sequence 2, 10, 50, ... if there are 7 terms?
r = 5
2 + 10 + 50 + 250 + 1250 + 6250 +31250 =...........
GP = 2,10,50,...
Let first term a, no. of terms n and common ratio r.
⇒a = 2
n = 7
Sum = \({a(r^n-1) \over (r-1)}\)
= \({2(5^7-1) \over (5-1)}\)
= 39062
+526 
