Permutations and Combinations Exercise 7.2

Exercise 7.2

1. Evaluate:

(i) 8!

(ii) (ii) 4! – 3!

Ans. (i) 8! = = 40320

(ii) 4! – 3! =

= 24 – 6 = 18

2. Is 3! + 4! = 7!?

Ans. L.H.S. = 3! + 4! =

= 6 + 24 = 30

R.H.S. = 7! = = 5040

L.H.S. R.H.S.

3. Compute:

Ans. Given: =

= = 28

4. If find

Ans. Given:

5. Evaluate: when

(i)

(ii)

Ans. (i) Given: and

= 30

(ii) Given: and

= 15120