Matematika

Pertanyaan

suatu fungsi dirumuskan dengan f(x) =ax + b. jika f(2) = 7 dan f(4) = 11, tentukan:
a. nilai a dan b
b. f(-3)

2 Jawaban

  • Jawab :
    Memakai cara Gabungan Eliminasi dan Substitusi

    f(x) = ax + b
    f(2) = 2a + b = 7.....(x2)
    f(4) = 4a + b = 11.....(x1)

    4a + 2b = 14
    4a + b = 11
    ------------------- -
    b = 3

    2a + b = 7
    2a + 3 = 7
    2a = 7-3
    a = 4/2
    a = 2

    Pembahasan soal :
    A.
    Nilai a = 2
    Nilai b = 3

    B.
    f(-3) = -3a + b
    f(-3) = -3(2)+3
    f(-3) = -6+3
    f(-3) = -3

    Selesai
  • f(x) =ax + b

    f(2) = 2a + b = 7
    f(4) = 4a + b = 11
          -------------------- (-)
              2a = 4
                
    a = 2

    2a + b = 7
    2(2) + b = 7
    b = 7 - 4
    b = 3

    f(x) = 2x + 3

    f(-3) = 2(-3) + 3
    f(-3) = -6 + 3
    f(-3) = -3

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