Question

find th sum of first n of odd natural numbers?

Answer 1

a(n) =a+(n-1).d Hope this is helpful for you

Answer 2

The first n natural numbers are
1, 3, 5, 7, 9.......(2n+1)
As they are in AP with
common difference=2,
first term =1,
number of terms = n
last term= 2n+1
So now applying the formula for sum of n terms in AP
$\frac{n}{2} (2a + (n - 1)d) = \frac{n}{2} (a + l)$
So now substituting the values in the formula:
$\frac{n}{2} (1 + 2n + 1) \\ = \frac{n}{2} (2 + 2n) \\ = \frac{n}{2} (2)(1 + n) \\ = n(n + 1)$
I HOPE IT HELPS YOU...!!!