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Math Help - Using discriminants

  1. #1
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    Using discriminants

    Use the discriminant to determine the number of real solutions of the quadratic equations.

    60. (-5xsquared - 4x + 4)= 0

    62. (xsquared - 4x + 4) = 0

    64. (4/7xsquared -8x + 28) =0

    66. (9 + 2.4x - 8.3xsquared)=0

    i don't know what it means by discriminant?
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  2. #2
    o_O
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    Given the quadratic ax^2 + bx + c = {\color{red}0} (the 0 is important), the discriminant refers to {\color{blue}b^2 - 4ac} which comes from the quadratic equation: x = \frac{-b \pm \sqrt{{\color{blue}b^2 - 4ac}}}{2a}

    Now, if:
    • b^2 - 4ac > 0, then there are 2 real solutions to x.
    • b^2 - 4ac = 0, then there is exactly 1 real solution to x.
    • b^2 - 4ac < 0, then there are no real solutions to x.


    See if you can apply this to your quadratics.
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  3. #3
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    Quote Originally Posted by o_O View Post
    Given the quadratic ax^2 + bx + c = {\color{red}0} (the 0 is important), the discriminant refers to {\color{blue}b^2 - 4ac} which comes from the quadratic equation: x = \frac{-b \pm \sqrt{{\color{blue}b^2 - 4ac}}}{2a}

    Now, if:
    • b^2 - 4ac > 0, then there are 2 real solutions to x.
    • b^2 - 4ac = 0, then there is exactly 1 real solution to x.
    • b^2 - 4ac < 0, then there are no real solutions to x.


    See if you can apply this to your quadratics.
    Thanks you rock.
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