Matematika

Pertanyaan

diketahui f(x+5)=3x^2+10x-3 dan g(4x-1)=1-8x/2x+2
Tentukan hasil berikut
a] f(x) dan g(x)
b] (f+3g) (-6)
c] (f.g) (-1)

1 Jawaban

  • a) misalkan p = x + 5
    p - 5 = x (ganti x dengan p-5)
    f(p) = 3(p-5)² + 10(p-5) - 3
    f(p) = 3(p² - 10p + 25) + 10p - 50 - 3
    f(p) = 3p² - 30p + 75 + 10p - 53
    f(p) = 3p² - 20p + 22
    f(x) = 3x² - 20x + 22
    g(4x-1) = 8x / 2x+2
    g(4x-1) = 2(4x-1)+2 / 0,5(4x-1)+2,5
    g(x) = 2x+2 / 0,5x+2,5

    b) f(6) = 3(-6²) - 20(-6) + 22 = 108+120+22 = 240
    f(6) = 2(-6)+2 / 0,5(-6)+2,5 = 10/0,5 = 20
    (f+3g)(-6) = 240 + 3(20) = 300

    c) f(-1) = 3(-1²) - 20(-1) + 22 = 3 + 20 + 22 = 45
    g(-1) = 2(-1)+2 / 0,5(-1)+2,5 = 0/2 = 0
    (f.g)(-1) = 45 × 0 = 0

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