Question

Calcule o valor de N

Answer 1

Resposta:

n=14

Explicação passo-a-passo:

(n+1)! /(n-1)!= 210

(n+1).n.(n-1)! /(n-1)!=210

(n+1).n= 210

n²+n=210

n²+n-210=0

a=1

b=1

c=-210

∆=b²-4.a.c

∆=(1)²-4.(1).(-210)

∆=1 +840

∆=841

n'=[ -(+1)+√841]/2.(1)

n'=[-1 +29] /2

n'= 28/2

n'= 14 ( serve)

n"=[-(+1)-√841]/2.(1)

n"=[ -1 -29]/2

n"=-30/2

n"=-15 (não serve )