Diketahui f(x) = 3x - 2 dan g(x) = x2 + 2x - 10. Tentukan: a. (g o f)(x) b. (g o f)(-1) c. g(a) jika (g o f)(a) = 14

Diketahui f(x) = 3x - 2 dan g(x) = x² + 2x - 10. Tentukan:

a. (g o f)(x)

b. (g o f)(-1)

c. g(a) jika (g o f)(a) = 14

Jawab:

f(x) = 3x – 2 dan g(x) = x² + 2x – 10

a. (g o f)(x) = g(f(x))

    = g(3x – 2)

    = (3x – 2)² + 2(3x – 2) – 10

    = 9x² – 12x + 4 + 6x – 4 – 10

    = 9x² – 6x – 10

b. (g o f)(-1) = 9(-1)² – 6(-1) – 10 = 9 + 6 – 10 = 5

c. (g o f)(a) = 14

    ⇔ 9a² – 6a – 10 = 14

    ⇔ 9a² – 6a – 24 = 0

    ⇔ 3a² – 2a – 8 = 0

    ⇔ 3a² – 2a – 8 = 0

    ⇔ (3a + 4)(a – 2) = 0

    ⇔ a = -4/3 atau a = 2

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Jangan Lupa Belajar Terus

Ingat Cita-Cita, Orang Tua, dan Keluarga

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