Question

the sum of first 20 odd natural numbers is​

Answer 1

Answer:

First 20 odd natural numbers:

First term, a=1

Common difference, d=2

Sum of first n terms of and AP:

2

n

(2a+(n−1)d)

Here, n=20,a=1,d=2

Substituting these, we get

Sum of first 20 natural numbers:

2

20

(2(1)+(20−1)2)

=10×(2+19×2)=10×40=400