Question

If nth term of an ap is 2n + 1 what is the sum of its first three terms

Answer 1

so let n=1

then n=2

hope its helpful

Answer 2

nth term: 2n+1

1st term: 2(1)+1=3

2nd term: 2(2)+1=5

3rd term: 2(3)+1=7

Sum of the three terms are 15