Question

Tolong dibantu yaa soal peluang matematika kelas X

Answer 1

NC3 = 2n
n!/(n-3)!3! = 2n
n(n-1)(n-2)(n-3)!/(n-3)!3! = 2n
n(n-1)(n-2)/3! = 2n
(n-1)(n-2)/3! = 2
(n-1)(n-2)/3x2x1 = 2
(n-1)(n-2)/6 = 2
(n-1)(n-2) = 12
n² - 3n + 2 = 12
n² - 3n - 10 = 0
(n - 5)(n + 2) = 0

n = 5 atau n = -2

karena n harus positif, jadi ambil n = 5

2nC3 = 2(5)C3
= 10C3
= 10!/(10-3)!3!
= 10!/7!3!
= 120