Matematika

Pertanyaan

Jika x + x^-1 = 3
Maka tentukan a. X^2+x^-2
B. X^3 + x^-3
C. X^4 + x^-4
D. X^5 + x^-5
Jika x + x^-1 = 3 Maka tentukan a. X^2+x^-2 B. X^3 + x^-3 C. X^4 + x^-4 D. X^5 + x^-5

1 Jawaban

  • kedua ruas kuadrat kan
    a) (x¹ + x^-1)² = 3²
    x² + 2 + x^-2 = 9
    x² + x^-2 = 9-2
    x² + x^-2 = 7

    b) (x^1 + x^-1)(x^2 + x^-2) = (3)(9)
    x^3 + x^1 + x^-1 + x^-3 = 27
    x^3 + 3 + x^-3 = 27
    x^3 + x^-3 = 27-3 = 24

    c) (x^2 + x^-2)² = 7²
    x^4 + 2 + x^-4 = 49
    x^4 + x^-4 = 49 - 2 = 47

    d) (x^3 + x^-3)(x^2 + x^-2) = (24)(7)
    x^5 + x^1 + x^-1 + x^5 = 168
    x^5 + 3 + x^-5 = 168
    x^5 + x^-5 = 168 - 3 = 165