Question

If nC2017:nC2018=2018:2017nC2017:nC2018=2018:2017 , then the value of nn  is​

Answer 1

Answer:

We have for

n

C

r

=

n

C

n−r

.

Now given

n

C

12

=

n

C

8

or,

n

C

n−12

=

n

C

8

⇒n−12=8

or, n=20.

Then

n

C

17

=

20

C

17

=

20

C

20−17

=

20

C

3

=

3.2.1

20.19.18

=20.57

=1140