College Algebra

3x^2-12x-24=0

asked by Edwin
  1. 3x^2- 12x - 24 = 0

    Solve the quadratic equation by completing the square:

    Divide both sides by 3:
    x^2 - 4x - 8 = 0
    Add 8 to both sides:
    x^2 - 4x = 8
    Add 4 to both sides:
    x^2 - 4x + 4 = 12
    Factor the left hand side:
    (x - 2)^2 = 12
    Take the square root of both sides:
    |x - 2| = 2 sqrt(3)
    Eliminate the absolute value:
    x - 2 = -2 sqrt(3) or x - 2 = 2 sqrt(3)
    Add 2 to both sides:
    x = 2 - 2 sqrt(3) or x - 2 = 2 sqrt(3)
    Add 2 to both sides:
    x = 2 - 2 sqrt(3) or x = 2 + 2 sqrt(3)

    posted by helper
  2. A wheel made 672 revolutions at 35 1/5 revolutions per minute. How many minutes did it rotates?

    posted by sharlette

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