Diketahui rumus fungsi f(2x – 3) = 4x – 5. Nilai dari f(-7)

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Pembahasan:

Cara 1:
f(2x – 3) = 4x – 5
f(2x – 3) = 2(2x – 3) + 6 – 5
               = 2(2x – 3) + 1
⇔ f(x) = 2x + 1
    f(-7) = 2 × (-7) + 1
            = -14 + 1 = -13
Cara 2:
f(2x – 3) = 4x – 5
    2x – 3 = -7
⇔     2x = -7 + 3
⇔     2x = -4
⇔       x = -4 ÷ 2 = -2
f(-7) = 4 × (-2) – 5
        = -8 – 5 = -13
  Jika f(x) = (x - 2)² - 4 dan g(x) = -f(x),