Question

The
sum
of first
natural
term 20 odd
number​

Answer 1

Answer:

400

Step-by-step explanation:

Hope It Helps!

Hope It Helps!Please Mark It As Brainlist!

Answer 2

Step-by-step explanation:

Given : 20 odd natural numbers.

To find : The sum of first 20 odd natural numbers by A.P

Solution :

The first 20 odd natural numbers are given by :

1,3,5,7,9......,37,39.

These form an A.P with $a_1=1$ , d=2 , n=20

Formula of sum of an A.P series s_n=\frac{n}{2}[2a_1+(n-1)d]s

n

=

2

n

[2a

1

+(n−1)d]

Put all the values in the formula,

s_n=\frac{n}{2}[2a_1+(n-1)d]s

n

=

2

n

[2a

1

+(n−1)d]

s_{20}=\frac{20}{2}[2(1)+(20-1)2]s

20

=

2

20

[2(1)+(20−1)2]

s_{20}=10[2+(19)2]s

20

=10[2+(19)2]

s_{20}=10[2+38]s

20

=10[2+38]

s_{20}=10[40]s

20

=10[40]

s_{20}=400s

20

=400

Therefore,The sum of first 20 odd natural numbers is 400.