Question

ajudaaa

(n-3)! dividido por (n-5)! = 42 ???????

Answer 1

Resposta:

(n-3)!/(n-5)!=42

(n-3).(n-4).(n-5)!/(n-5)! =42

(n-3).(n-4)=42

n^2+4n-3n+12=42

n^2+n+12-42=0

n^2+n-30=0

∆=1+120

∆=121

n'=-1+11/2

n'=10/2=5

n"-1-11/2

n"=-12/2=-6

Answer 2

Resposta:

N=10

Explicação passo-a-passo:

(n-3)! /(n-5)! = 42

(n-3).(n-4).(n-5)!/(n-5)!=42

(n-3).(n-4)=42

n²-4n-3n+12=42

n²-7n+12-42=0

n²-7n-30=0

∆=b²-4.a.c

∆=(-7)²-4.(1).(-30)

∆=49+120

∆=169

n'=-(-7)+√169/2=7+13/2=20/2=10

n"=-(-7)-√169/2=7-13/2=-6/2=-3

n=10 (serve)

n"=-3 (não serve)

Espero ter ajudado!