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Math Help - Simple quadratic question

  1. #1
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    Simple quadratic question

    When using the quadratic formula, if the coefficient of x squared is negative does that mean a is negative or absolute?
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  2. #2
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    Quote Originally Posted by olivia59 View Post
    When using the quadratic formula, if the coefficient of x squared is negative does that mean a is negative or absolute?
    Of course a is negative.

    Here is an example:

    Solve for x:

    -3x^2+21x-30=0 Using the quadratic formula:

    x=\dfrac{-21 \pm \sqrt{21^2-4 \cdot (-3) \cdot (-30)}}{2 \cdot (-3)}

    yields

    x=2~\vee~x=5
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  3. #3
    Senior Member pacman's Avatar
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    When using the quadratic formula, if the coefficient of x squared is negative does that mean a is negative or absolute?

    ax^2 + bx + c = 0 is the quadratic equation. The coefficient of x^2 which is a can be positive or negative.

    -2x^2 + x + 3 = 2x^2 - x - 3 = 0, but in case you have this -2x^2 + x + 3 = 0, using quadratic formula, a = -2. But if you choose 2x^2 - x - 3 = 0, then a = 2.
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  4. #4
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    Quote Originally Posted by olivia59 View Post
    When using the quadratic formula, if the coefficient of x squared is negative does that mean a is negative or absolute?
    If a is negative, then a is negative.
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