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Math Help - functions question

  1. #1
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    Cool functions question

    Regarding f(x) = 3x(squared) -x -2...

    If x=2, what is f(x)?

    Supposedly, I'm to factor something here to get the answer.

    Thanks in advance for any help you can provide!!

    I've got a handful of questions like this, and about four sub-chapters pending after it. . . all due by tomorrow night!
    Attached Thumbnails Attached Thumbnails functions question-helpme.bmp  
    Last edited by petedude; June 29th 2008 at 09:11 AM. Reason: urgency
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  2. #2
    Senior Member nikhil's Avatar
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    Lightbulb Here it is

    Quote Originally Posted by petedude View Post
    Regarding f(x) = 3x(squared) -x -2...
    If x=2, what is f(x)?
    f(x) will always be 3x^2-x-2 as f(x) is pre defined so i guess you wanted to ask f(2) or value of f(x) at x=2 which is given as
    f(2)=3(2)^2-2-2=12-4=8
    hence 8 is the answer.
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  3. #3
    A riddle wrapped in an enigma
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    (c) If f(x)= -2, what is x? What point(s) are on the graph of f ?

    f(x)=3x^2-x-2

    f(x)=3x^2-x-2=-2

    3x^2-x=0

    x(3x-1)=0

    x=0 \ \ or \ \ x=\frac{1}{3}

    Two points on the graph would be the x-intercepts (0, 0) and (1/3, 0).

    (d) What is the domain of f ?

    D=\{x|x\in\Re\} (i.e. all real numbers)

    (e) List the x-intercepts of f(x)=3x^2-x-2

    3x^2-x-2=0

    (x-1)(3x+2)=0

    x=1 \ \ or \ \ x=-\frac{2}{3}

    x-intercepts \ \ are \ \ (1, 0) \ \ and \ \ (-\frac{2}{3}, 0)

    (f) List the y-intercept, if any, of the graph of f.

    f(x)=3x^2-x-2

    f(0)=3(0)^2-2(0)-2 = -2

    y-intercept = -2
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