Question

If n+1c3=4.nc2 then n-4​

Answer 1

Answer:

Given that,

n+1

C

3

=4.

n

C

2

Then n=?

n+1

C

3

=4.

n

C

2

⇒

3!(n+1−3)!

(n+1)!

=4.

2!(n−2)!

n!

⇒

3×2!(n−2)!

(n+1)n!

=4.

2!(n−2)!

n!

⇒

3

(n+1)

=4

⇒n+1=12

⇒n=12−1=11