Question

If the n th term of an AP is 2n+1. Then the sum of first three terms is

• A. 15
• B. 12
• C. 21
• D. 8

Answer 1

Answer:

A. 15

$a_n=2n+1$

$a_1= 3$

$a_2=5$

$a_3=7$

$3+5+7=15$