Question

11. Find the sum of first n even natural number​

Answer 1

0+1+2+3+4+5+6+7+8+9 =45

Answer 2

Answer:

First n even natural numbers: 2,4,6,8,10,,n

Here, a=2,d=4−2=2

Sum =S

n

=

2

n

[2a+(n−1)d]

=S

n

=

2

n

[2(2)+(n−1)2]

=n(n+1).