Mark the correct alternative in each of the following: If second term of a G.P. is 2 and the sum of its infinite terms is 8, then its first term is

Question

Philoid · Accepted Answer

Let the GP be a,ar,ar²

Sum of infinite terms is given by

⇒

Also according to the question ar =2

∴

Substituting in above equation

⇒

⇒ 8(a-2) =a²

⇒ a²-8a+16 = 0

⇒ (a-4)² = 0

⇒ a =4.