How many terms of the sequence 
must be taken to make the sum 
?
Given:
Sum of GP = 39 + 13√3
∴ Common Ratio = r = 
a = √3
To find: Number of terms = n.
Sum of GP for n terms = 
⇒ 
⇒ 
⇒ 
⇒ 26√3 = √3(3n - 1)
⇒ 27 = 3n
⇒ n = 3.
7
How many terms of the sequence must be taken to make the sum ?
Given:
Sum of GP = 39 + 13√3
∴ Common Ratio = r =
a = √3
To find: Number of terms = n.
Sum of GP for n terms =
⇒
⇒
⇒
⇒ 26√3 = √3(3n - 1)
⇒ 27 = 3n
⇒ n = 3.