Question

If the second term of a G.P. is 2 and the sum of its infinite terms is 8, then its first term is

• A. $\frac { 1 } { 2 }$
• B. $\frac { 1 } { 4 }$
• C. 2
• D. 4

Answer 1

Answer: (D)

4

Answer 2

Let a be the first term and r be the common ratio of infinite G.P. then

ar = 2 ….(1)

Also, $\frac { a } { 1 - r } = 8$ ….(2)

form equation (1), r = $\frac { 2 } { \mathrm { a } }$ put in equation (2)

a = 4.