Matematika

Pertanyaan

jika 7p + 4q =2 dan 4p + 2q =2 maka nilai dari 3p +5q adalah?

2 Jawaban

  • Memakai cara eliminasi
    7p + 4q = 2 |x4|
    4p + 2q = 2 |x7|
    ____________
    28p + 16q = 8
    28p + 14q = 14
    ____________ -
    2q = -6
    q = -6/2
    q = -3

    7p + 4q = 2
    7p + 4(-3) = 2
    7p + (-12) = 2
    7p = 2 + 12
    7p = 14
    p = 14/7
    p = 2

    3p + 5q = 3(2) + 5(-3)= 6 + (-15) = -9
  • persamaan
    7p + 4q = 2
    4p + 2q = 2 [x2] 8p + 4q = 4

    eliminasi
    8p + 4q = 4
    7p + 4q = 2
    -----------------(-)
    p = 2

    substitusi
    4p + 2q = 2
    4(2) + 2q = 2
    8 + 2q = 2
    2q = 2 - 8
    2q = -6
    q = -6/2
    q = -3

    maka nilai 3p +5q 
    3(2) +5(-3)
    = 6 + (-15) 
    = 6 - 15
    = -9

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