Matematika

Pertanyaan

diketahui fungsi f :r=r dan fungsi g :r=r ditentukan oleh rumus f (x) = 2x-3 dan g (x) =x kuadrat -x-2 tentukan:
a.rumus fungsi (gof) x (x) dan (fog) (x)
b. nilai fungsi (gof) (-4)
c. nilai fungsi (fog) (4)

2 Jawaban

  • f(x) = 2x - 3
    g(x) = x² - x - 2

    a) (fog) (x) dan (gof) (x)
    (fog) (x) = f(x² - x - 2)
    (fog) (x) = 2(x² - x - 2) - 3
    (fog) (x) = 2x² - 2x - 4 - 3
    (fog) (x) = 2x² - 2x - 7

    (gof) (x) = (2x - 3)² - (2x - 3) - 2
    (gof) (x) = 4x² - 12x + 9 - 2x + 3 - 2
    (gof) (x) = 4x² - 14x + 10

    B) (gof) (-4) = 4(-4)² - 14(-4) + 10
    (gof) (-4) = 64 + 56 + 10
    (gof) (-4) = 130

    C) (fog) (4) = 2(4)² - 2(4) - 7
    (fog) (4) = 32 - 8 - 7
    (fog) (4) = 17
  • Diket :
    f(x)= 2x-3
    g(x)= x²-x-2
    ditanya :
    a.) rumus (gof) (x) Dan (fog) (x)...?
    b.) (gof) (-4)...?
    c.) (fog) (4)...?
    jawab :
    a.) (gof) (x)
    = g(fx)
    = g(2x-3)
    = (2x-3)²-(2x-3)-2
    = (2x-3)(2x-3)-2x+3-2
    = 4x²-6x-6x+9-2x+1
    = 4x²-14x+10
    (fog) (x)
    = f(gx)
    = f(x²-x-2)
    = 2(x²-x-2)-3
    = 2x²-2x-4-3
    = 2x²-2x-7
    b.) (gof) (-4)
    = g(f-4)
    = g(2.-4 - 3)
    = g(-8-3)
    = g(-11)
    = (-11)²-(11)-2
    = 121-11-2
    = 108
    c.) (fog) (4)
    = f(g4)
    = f(4²-4-2)
    = f(16-4-2)
    = f(10)
    = 2(10)-3
    = 20-3
    = 17

    SEMOGA MEMBANTU

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