Question

Question 12

Write the correct answer from the given four options.

The sum of first n odd natural numbers is

a) $2n+1$
b) $n^2$
c) $n^2-1$
d) $n^2+1$

Answer 1

Sum of first n odd natural numbers $=\sum (2n-1)=2\sum n-n$
$=\frac{2\times n(n+1)}{2}-n=n(n+1)-n=n^2+n-n=n^2$