Question

Yang Hebat bisa bantu saya???

Answer 1

13.
nP2= 72
n! / (n-2)! = 72
(n)(n-1) (n-2)! / (n-2)! = 72
(n)(n-1) = 72
n²-n-72 = 0
(n-9)(n+8) = 0
n = 9atau n = -8

14.
(n-1)P2 = 110
(n-1)! / (n-1-2)! = 110
(n-1)(n-2) (n-3)! / (n-3)! = 110
n²-3n+2 = 110
n²-3n-108 = 0
(n-12)(n+9) = 0
n = 12 atau n = -9

15.
8C5 = 8! / (8-5)!5! =
8. 7. 6. 5! / 3!5! =
8.7.6 / 3.2.1 =
8.7 = 56

16.
7C4 - 8C6 =
7! / 4!(7-4)! - 8! / 6!(8-6)! =
(7. 6. 5) / (3. 2. 1) - (8. 7) / (2. 1) =
35 - 28 = 7

17.
nC2 = 21
n! / 2!(n-2)! = 21
(n)(n-1) (n-2)! / 2(n-2)! = 21
n²-n = 42
n²-n-42 = 0
(n+7)(n-6) = 0
n=-7 atau n=6