Question

the sum of first n odd positive integers is​

Answer 1

Answer:

the sum of first n positive integers is n(n+1)/2

Answer 2

The sequence of the first n odd positive integer numbers is 1,3,5,7,9,...,2n−1.
a
1
​
=1,d=2
We know that S
n
​
=a
1
​
+a
2
​
+a
3
​
+....a
n
​
=
2
n
​
[2a
1
​
+(n−1)d]
S
n
​
=
2
2n−1
​
[(2×1+2n−1−1)×2]
S
n
​
=
2
2n−1
​
[(2n)×2]
S
n
​
=2n(2n−1)
S
n
​
=4n
2