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Math Help - Parabola

  1. #1
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    Parabola

    find the value of the discriminant: Use that number to describe the nature of the roots:

    a. 12x^2+2x+5=0

    b. x^2+6x=0


    2: suppose f(x)=3x^2+2x1
    a. find x if f(x)=7
    b. find the x-intercepts
    c. find f(-4)
    d.find (2)
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  2. #2
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    for ax^2+bx+c=0 the discriminant is \Delta = b^2-4ac

    When

    \Delta >0 your quadratic has two distinct real roots

    \Delta =0 your quadratic has one repeated real root

    \Delta <0 your quadratic has no real roots

    for 12x^2+2x+5=0 then a = 12, b=2 and c = 5

    so \Delta = 2^2-4\times 12 \times 5 = \dots

    finish this and make your conclusion.
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  3. #3
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    Quote Originally Posted by Kayla View Post
    find the value of the discriminant: Use that number to describe the nature of the roots:

    a. 12x^2+2x+5=0

    b. x^2+6x=0
    Do you know that the discriminant of ax^2+ bx+ c= 0 is b^2- 4ac.


    2: suppose f(x)=3x^2+2x1
    was this supposed to be "+ 1"? I will assume f(x)= 3x^2+ 2x+ 1.

    a. find x if f(x)=7
    Solve 3x^2+ 2x+ 1= 7

    b. find the x-intercepts
    Those are where f(x)= 0. Solve 3x^2+ 2x+ 1= 0.

    c. find f(-4)
    That is just 3(-4)^2+ 2(-4)+ 1.

    d.find (2)
    Assuming you mean f(2), it is just 3(2)^2+ 2(2)+ 1.
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