Question 1: Evaluate      (i) 8!       (ii) 4! – 3!

Answer 1:

(i) 8! = 1 × 2 × 3 × 4 × 5 × 6 × 7 × 8 = 40320

(ii) 4! = 1 × 2 × 3 × 4 = 24

 3! = 1 × 2 × 3 = 6

∴ 4! – 3! = 24 – 6 = 18

Question 2: Is 3! + 4! = 7!?

Answer 2: 3! = 1 × 2 × 3 = 6

4! = 1 × 2 × 3 × 4 = 24

∴ 3! + 4! = 6 + 24 = 30 7!

= 1 × 2 × 3 × 4 × 5 × 6 × 7 = 5040

∴ 3! + 4! ≠ 7!

Question 3: Compute

Answer 3:

Question 4: If , find x.

Answer 4:

∴ x=64

Question 5: Evaluate , when

(i) n = 6, r = 2          (ii) n = 9, r = 5

Answer 5:

(i) When n = 6, r = 2:

(ii) When n = 9, r = 5:

= 9 x 8 x 7 x 6 x 5 = 15120