Question

Q: The value of n when nC3-n27 is​

Answer 1

Step-by-step explanation:

8

n

C

3

:

n−1

C

4

=8:5

n−1

C

4

n

C

3

=

5

8

(n−1−4)!4!

(n−1)!

(n−3)!3!

n!

=

5

8

(n−3)(n−4)

n

=

5

2

5n=2(n

2

−7n+12)

2n

2

−19n+24=0

2n

2

−16n−3n+24=0

(n−8)(2n−3)=0

n=8,

2

3

n=8,(n



=

2

3

)