Anonymous
Anonymous asked in Science & MathematicsMathematics · 9 years ago

Solve x^2 + 9x + 9 = 0 ((10 points best answer))?

Using the quadratic formula

3 Answers

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  • Anonymous
    9 years ago
    Favorite Answer

    a = 1, b = 9, c = 9

    - 9 +/- Sqrt(81 - 4*1*9) / 2

    - 9 +/- Sqrt(81 - 36) / 2

    - 9 +/- Sqrt45 / 2

    - 9 +/- Sqrt9*Sqrt5 / 2

    - 3 +/- 3Sqrt5 / 2

    x = 3/2(-3 - Sqrt5)

    x = 3/2(Sqrt5 - 3)

  • Anonymous
    9 years ago

    Answer: x = [-9 +/- 3sqrt5]/2

    Method:

    The quadratic formula states that x = [-b +/- sqrt(b^2 - 4ac)]/2a. In this case, a = 1, b = 9, and c = 9, so just plug those values into the formula:

    x = [-9 +/- sqrt(9^2 - 4*1*9)]/2*1

    x = [-9 +/- sqrt(81 - 36)]/2

    x = [-9 +/- sqrt(45)]/2

    x = [-9 +/- 3sqrt5]/2

  • 9 years ago

    x^2 + 9*x + 9 = 0

    a = 1, b = 9, c = 9

    b^2 - 4*a*c = 81 - 4*1*9 = 45 = 9*5

    x1 = ( - 9 + 3*sqrt(5))/2 = - 9/2 + (3/2)*sqrt(5)

    x2 = - 9/2 - (3/2)*sqrt(5)

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