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Expanding a cubic problem

  1. May 18, 2013 #1
    1. The problem statement, all variables and given/known data


    I have a question that I have to do that involves expanding a cubic. It is given in the form y = , once it is found I have to square it and then substitute it into a formula to find the area. All I need help with is the expansion than after that it's quite easy.

    2. Relevant equations

    Sorry I don't know how to use the options here to create formulas etc. But I hope the following link works.


    This is the equation that I need to expand.

    3. The attempt at a solution

    I know how to expand a cubic already, it's not that difficult. The problem is with the +2 at the end of the equation. Do I ignore it, expand the brackets and add it on at the end?

    Attached Files:

  2. jcsd
  3. May 18, 2013 #2


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    Hi Grove1996,

    Usually you would do the operations in the brackets first and then simplify after. So yes you would need to add the 2 to the constant from the cubic expansion

    So when do any expansion, you would sum up all the x's and constants and so on.

    e.g. (x+1)2+4 = (x+1)(x+1) + 4 = x2 + x +x +1 +4 = x2 + 2x + 5
  4. May 18, 2013 #3
    Thank you :)
  5. May 18, 2013 #4

    Attached Files:

  6. May 18, 2013 #5
    Yes, it is correct, but you can further simplify it:

    For example:
    ## -1.5 x^4 -3 x^4 = (-1.5 - 3)x^4 = -4.5x^4 ##
  7. May 19, 2013 #6


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    In other words: Combine like terms.
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