Matematika

Pertanyaan

diketahui f(x) = 2x^2-3x+6 dan (g°f)(x) = 10x^2-15x+32. Nilai g(-1) = ………

1 Jawaban

  • (gof)(x) = 10x² - 15x + 32
    g(f(x)) = 10x² - 15x + 32
    g(2x² - 3x + 6) = 10x² - 15x + 32

    Misal 2x² - 3x + 6 = a
             2x² - 3x = a - 6

    g(2x² - 3x + 6) = 5(2x² - 3x) + 32
    g(a) = 5(a - 6) + 32
           = 5a - 30 + 32
           = 5a + 2
    g(x) = 5x + 2

    g(-1) = 5(-1) + 2 = -3

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