Question

if the last term of an ap Is (2n-+1) then find the sum of 1st three terms

Answer 1

given in a ap

an= 2n+1

then a1=3
a2=5
a3=7

a1+a2+a3=3+5+7=15

Answer 2

Answer:

Step-by-step explanation:

since

an = 2n + 1

a1 = 2(1) + 1

a1 = 3

a2 = 2(2)+ 1

a2 = 5

a3 = 2(3)+ 1

a3 = 7

so the sum of .1st three term = 3 + 5 + 7

= 15