Question

find the sum of ap whose nth term is (2n+1)​

Answer 1

Answer:

given: an=(2n+1)

=> a=2(1)+1= 2+1=3

=> a2= 2(2)+1= 4+1=5

=>d= a2-a1= 5-3=2

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

= n/2 (2(5)+(n-1)2)

= n/2 (10+2n-2)

= n/2 (8+2n)

= n (4+n)

= n²+4n

hope it helps u......^_^