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Math Help - Writing an Equation.

  1. #1
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    Writing an Equation.

    Question:

    Write a Determine the values of b and c such that f(x) = x^2 + bx + c passes through the points (-4,0) and (3,14)

    I'm not sure how to approach the problem. I have tried using vertex version of quadratic formula a(x-h)^2+k, but the problem does not specify which ordered pair is the vertex. I also tried plugging into the ordered pairs into my graphing calc, and got an error because I need three ordered pairs for it to give me an expression.

    Suggestions?
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  2. #2
    Super Member flyingsquirrel's Avatar
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    Hi
    Quote Originally Posted by JoeF107 View Post
    Question:

    Write a Determine the values of b and c such that f(x) = x^2 + bx + c passes through the points (-4,0) and (3,14) [...]

    Suggestions?
    We know that the curve passes through (-4,0) and (3,14) which means that f(-4)=0 and that f(3)=14. Using these two equalities, can you find the value of b and c ?
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  3. #3
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    Quote Originally Posted by flyingsquirrel View Post
    Hi

    We know that the curve passes through (-4,0) and (3,14) which means that f(-4)=0 and that f(3)=14. Using these two equalities, can you find the value of b and c ?
    ah, I was over thinking the problem. thanks
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  4. #4
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    16-4b+c=3
    9+3b+c=14

    subtracting above equations

    -7b=-18
    b=18/7

    substitute b=18/7 in -4b+c=-13
    then c=-19/7
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