Tentukan nilai n yang memenuhi : 6nC2=(n+2)C4
Matematika
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Pertanyaan
Tentukan nilai n yang memenuhi : 6nC2=(n+2)C4
2 Jawaban
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1. Jawaban CAPTAINROCKY1
6nC2=(n+2)C4
6nC2= nC4+8
6-8= nC4/nC2
-2= 2n
-1 = n -
2. Jawaban arsetpopeye
6 . nC2 = (n + 2)C4
6 . n!/(n - 2)!2! = (n + 2)!/(n + 2 - 4)!4!
6 . n(n - 1)(n - 2)!/(n - 2)!.2.1 = (n + 2)(n + 1)(n)(n - 1)(n - 2)!/(n - 2)!4.3.2.1
6 . n(n - 1) / 2 = (n + 2)(n + 1)n(n - 1)/24
6 / 2 = (n + 2)(n + 1)/24
3 = (n^2 + 3n + 2)/24
3(24) = n^2 + 3n + 2
n^2 + 3n + 2 - 72 = 0
n^2 + 3n - 70 = 0
(n + 10)(n - 7) = 0
n = -10 atau n = 7
Yang kita ambil n = 7 => harus bilangan asli