Question

Find the sum of first n even natural numbers and also find the sum of first 20 even natural
numbers. answer it urgently​

Answer 1

Answer:

a=2

D=2

s20 = n/2 (2a + n-1×d)

= 10 (4 + 38)

= 10 (42)

= 420

Answer 2

Answer:

a = 2

d = 2

sn = n/2(2a + (n - 1)d)

=> n/2(4 + (n - 1)2)

=> n(2 + n - 1)

=> n^2 + n

When n = 20:

=> 400 + 20

=> 420

_____________