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Math Help - using polynomials

  1. #1
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    Question using polynomials

    The problem states:The volume of the box is 630in^3. The height is 4 in more than the width, the length is 1 in more than than width.What is the width?

    I started by forming the equation based on l*w*h=v so,

    (1+w)(4+w)(w)=630 and i combined to get

    w^3+5w^2+4w=630

    And from this point I'm stuck
    Last edited by vidalex; March 27th 2009 at 01:41 AM.
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  2. #2
    Super Member craig's Avatar
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    Your work so far is correct, rearranging the formula you have above will give you the following cubic equation:

    w^3 + 5w^2 + 4w - 630 = 0

    Have you been taught how to solve cubic equations?
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  3. #3
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    No this is an extra credit problem for this unit. We've covered how to find zeros but this problem has me stumped.


    Quote Originally Posted by craig View Post
    Your work so far is correct, rearranging the formula you have above will give you the following cubic equation:

    w^3 + 5w^2 + 4w - 630 = 0

    Have you been taught how to solve cubic equations?
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  4. #4
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    Talking

    If you're using graphing calculators in your class, maybe you're expected to use that to find where the polynomial crosses the x-axis...?
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