Question 1202472
Find S9 of a geometric series if t1 = 2 and t6 = 486.



tn = ar^(n-1)

n= number of terms
a = first term

t1=2

t6 = 2*r^5= 486
r^5 =243
r=3

Sum of n terms ={{{Sn = a*(1 - r^n) / (1 - r)}}}

S9 = 2*(1-3^9)/(1-3)

= 19682