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Homework Help: Simplifying an expression

  1. Nov 30, 2007 #1
    1. The problem statement, all variables and given/known data
    2a^2*b^2*c^2 + (a+c)^2*(a+b)^2*(b+c)^2 - a^2*c^2(a+c)^2 - (a+b)^2 * a^2 * b^2 - (b+c)^2*b^2*c^2 = 2abc(a+b+c)^3

    2. Relevant equations

    3. The attempt at a solution

    Well I actually tried to expand all of the exponential terms but that ended up being a total mess and wasn't even remotely obvious... My professor said using something like (a-b)^2 = (a+b)(a-b) would help, but I don't quite see how that would help.. can anyone give me a hint?
  2. jcsd
  3. Nov 30, 2007 #2


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    Staff Emeritus
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    Gold Member

    ya only tried once? I find that I need to work through complicated expressions multiple times. Don't give up keep after it. You may want to show us some of your work. If you do pleas go to the tutorials forum and read the latex thread.
  4. Dec 1, 2007 #3
    Try it in parts. When I solve problems that look like a mess I'll draw lines down a paper and group it by addition/subtractions. That way you're just dealing with each part individually.

    \underbrace{2a^2*b^2*c^2}_{First} + \underbrace{(a+c)^2*(a+b)^2*(b+c)^2}_{Second} - \underbrace{a^2*c^2(a+c)^2}_{Third} - \underbrace{(a+b)^2 * a^2 * b^2}_{Fourth} - \underbrace{(b+c)^2*b^2*c^2}_{Fifth} &=& \underbrace{2abc(a+b+c)^3}_{Sixth}

    Now that you've grouped off your terms. Expand these out, simplify. The solution may become obvious (or at least easier) to find. When you're done, you may be left with something as simple as a quadratic, but don't quote me on that. I've not done the problem myself.
    Last edited: Dec 1, 2007
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