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Homework Help: Proper Methods

  1. Feb 20, 2007 #1
    I have this equation. 135=w(w+12)
    Would random plugging in numbers into w effective? If not, please help me out... I know how to get to the answer i just need a better grasp on methods
  2. jcsd
  3. Feb 20, 2007 #2
    This is a volume equation from your other post and it is not quite correct yet. Once you get the equation correct, I can help you solve it.
  4. Feb 20, 2007 #3


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    Homework Helper

    You mean, you need to solve for w? In that case, do you know how to find the roots of a quadratic equation?
  5. Feb 20, 2007 #4
    here i go...
    w^2+12W-135= 0
    then blah blah blah quadratic formula.
  6. Feb 20, 2007 #5


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    Venger; please don't start another thread, when you were already being helped in your first thread!

    Your equation is not correct; it should be a cubic. The method I suggested to you regarding a different cubic equation was not simply "randomly substitute numbers." You make an educated guess as to what the value of w could be (note, it must be a factor of 135) and then see if it solves the equation.
  7. Feb 20, 2007 #6
    Wait a minute this all can be cleared by one question. Is it possible to do a quadratic formula in a cubic equation? I know Im not at my full brain capacity today...
  8. Feb 20, 2007 #7


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    Is a cubic equation a quadratic equation?
    Thus, can we use the quadratic equation to solve it?

    Answer these and the answer to your question will be obvious.

    I'm gonna leave this to someone else now, since I don't think you're reading my posts; and if you are, you're definitely not thinking about the questions and points I'm posing to you.
  9. Feb 20, 2007 #8
    I've been at this question for 2 hours now... I just don't comprehend. Well here i go if i don't get this right this time I'm dropping calculas.
    Am i right so far?
  10. Feb 20, 2007 #9
    Check your algebra.
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