Questões de matemática (FATORIAL)?

lauro-plauro-p
in Science & Mathematics

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

Comments

  • miguelmiguel

    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

  • fjfj

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

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

    c) n + 2

    ----- = 4

    n - 1

    {n = 2}

  • einsteineinstein

    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

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