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Math Help - Discriminant

  1. #1
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    Discriminant

    Use the discriminant to determine whether each quadratic equation has two unequal real solutions, a repeated real solution, or no solution, WITHOUT solving each equation below.

    (1) x^2 + 5x + 7 = 0

    (2) 2x^2 - 3x + 4 = 0

    NOTE: What is the correct definition of a discriminant?
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  2. #2
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    Check the discriminant, as it says. If it's positive, then you have 2 unequal real roots. If it's negative, no real roots. If it's 0, one root of multiplicity 2.

    The discriminant is what's under the radical in the quadratic formula.

    b^{2}-4ac
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  3. #3
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    ok

    I simply plug the value of a, b and c as found in each equation into the discriminant, right?

    Afterward, I simplify, right?
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  4. #4
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    Quote Originally Posted by symmetry View Post
    I simply plug the value of a, b and c as found in each equation into the discriminant, right?

    Afterward, I simplify, right?
    Hello,

    that's 100% correct.

    With your first example:

    a = 1
    b = 5
    c = 7
    Thus the discriminant d = 5-4*1*7=-3. Therefore there exists no real solution.

    EB
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  5. #5
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    ok

    Earboth,

    Boy, this is very easy stuff. The question itself is not clear when first read but none the less very easy to handle.

    Thanks!
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