Question

if the n term of an ap is (2n+1) then find the sum of first n terms ​

Answer 1

Answer:

Step-by-step explanation:n^2+ 2n is the answer

Answer 2

Answer:

Given nth term = 2n+1⇒ a1= 2(1)+1=3.

similarly a2= 5.

now d = a2-a1=2;

Sn (n/2)[a+l] where l is the last term=an= 2n+1;

sn=(n/2)(3+2n+1)⇒sn= n(n+2)=n^2+2n

Step-by-step explanation: