Matematika

Pertanyaan

Jika akar-akar persamaan x^2+ax+b memenuhi persamaan 2x^2-(a+3)x+(3b-2)=0, maka...

2 Jawaban

  • x^2 + ax + b = 0
    x1 + x2 = -a
    x1x2 = b

    2x^2-(a+3)x+(3b-2)= 0
    x1 + x2 = -a-3/2
    x1x2 = 3b-2/2

    -a = -a-3/2
    -2a = -a-3
    -2a+a = -3
    -a = -3
    a = 3

    b = 3b-2/2
    2b = 3b-2
    2b-3b = -2
    -b = -2
    b = 2

    Jadi persamaannya adalah :
    x^2+3x+2
  • jawab

    (i) x² + ax + b = 0
    (ii) 2x² -(a+3)x + (3b -2)= 0

    2(i) = (ii)
    2(x² + ax + b) = 2x² - (a+3)x + (3b -2)
    2x² + 2ax + 2b= 2x² -(a+3)x + (3b -2)

    2a = -(a+3)
    2a = -a - 3
    3a = - 3
    a =  -1

    2b = 3b -2
    -b = - 2
    b = 2

    maka
    a= - 1, b = 2

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