คณิตศาสตร์ · hard · pol68-059
กำหนด และ
ข้อใดคือค่าของ
- a.512
- b.100
- c.1000
- d.1,331
C(n,r) = 120, P(n,r) = 720
P = C × r! → 720 = 120 × r! → r! = 6 → r = 3
C(n,3) = 120 → n(n-1)(n-2)/6 = 120 → n = 10
n^r = 10³ = 1000
P = C × r! → 720 = 120 × r! → r! = 6 → r = 3
C(n,3) = 120 → n(n-1)(n-2)/6 = 120 → n = 10
n^r = 10³ = 1000