Question

Explain term of ap is 2n+1 what is the sum of first three terms

Answer 1

given AP of n th term is 2n+1
put n=1
2(1)+1=3
put n=2
2(2)+1=5
put n=3
2(3)+1
=7
so 3+5+7=15
answer is 15
I HOPE THIS WILL HELP U

Answer 2

a1 = 2x1 + 1 = 3

a2 =2x2 +1 = 5

a3 =2x3 +1 = 7

d= a2-a1 = 2

Sn = n/2[2a+(n-1)d]

S3 =3/2[2x3+(3-1)2]

S3 = 3/2[6+4]

S3 = 3/2(10)

S3 = 3(5)

S3 =15 (answer)