Questões de matemática (FATORIAL)?

lauro-p

Pessoal, eu faltei aula por causa de uma viagem, e perdi a explicação

mas preciso entregar umas quetões, me ajudem?????

a) (n+3)! - (n+4)! / (n+2)!

b) (x+2)! / 3! x! = x! / (x-1)!

c) (n+2)! . (n-2)! / (n+1)! . (n-1)! = 4

miguel

a) (n+3)! - (n+4)! / (n+2)!

(n+3)(n+2)! - (n+4)(n+3)(n+2)! / (n+2)!

(n+3)- (n+4)(n+3)=

=n+3-{n²+3n+4n+12}

=n+3-n²-3n-4n-12

=-n²-6n-9

b) (x+2)! / 3! x! = x! / (x-1)!

(x+2)(x+1)x! / 3! x(x-1)! = x! / (x-1)!

(x+2)(x+1)/ 3! x = 1

(x+2)(x+1) = 3! x

x²+x+2x+2=6x

x²-3x-4=0

c) (n+2)! . (n-2)! / (n+1)! . (n-1)! = 4

(n+2)(n+1)! . (n-2)(n-1)! / (n+1)! . (n-1)! = 4

(n+2) (n-2)= 4

n²-4=4

n²-8=0

fj

a) (n+3)! - n^2 - 7*n - 12

b)(1/6) * (x+2)! * x! = x

c) n + 2

----- = 4

n - 1

{n = 2}

einstein

a) (n+3)! - (n+4)! / (n+2)!

(n+3)(n+2)! - (n+4)(n+3)(n+2)! / (n+2)!

(n+3)- (n+4)(n+3)=

=n+3-{n²+3n+4n+12}

=n+3-n²-3n-4n-12

=-n²-6n-9

b) (x+2)! / 3! x! = x! / (x-1)!

(x+2)(x+1)x! / 3! x(x-1)! = x! / (x-1)!

(x+2)(x+1)/ 3! x = 1

(x+2)(x+1) = 3! x

x²+x+2x+2=6x

x²-3x-4=0

c) (n+2)! . (n-2)! / (n+1)! . (n-1)! = 4

(n+2)(n+1)! . (n-2)(n-1)! / (n+1)! . (n-1)! = 4

(n+2) (n-2)= 4

n²-4=4

n²-8=0