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Homework Help: Need some assistance with integration

  1. Jul 12, 2010 #1
    1. The problem statement, all variables and given/known data

    ∫ x^(5)-2x^(2)-1/3x^(4) dx

    2. Relevant equations

    I am familiar with the power rule and how to split the expression into three separate expressions and then simplifying. I just cant seem to sort out my algebra for this problem.

    xn dx = xn+1

    n + 1 + C if n is NOT= -1
    x-1 dx = ln|x|+ C

    3. The attempt at a solution

    Here is where i become stuck...Please show me a step by step process to solving the remainder of this problem; that way i can analyze it more deeply. Please Point out any things that seem wrong,i would REALLY appreciate the help given. :) :


    ∫ (x^5/3x^4 -2x^2/3x^4 -1/3x^4)dx = ∫ 1/3x -2x^(-2) -1/3x^(-4)dx = ∫ (x^2/6 + 2/x +1/9x^3) + C <------- This is the part where i become flabbergasted. . .Its simple im sure but i just cannot see it. I was thinking about multiplying the whole expression by 18x^3 but i am not sure if that is correct.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
    Last edited: Jul 12, 2010
  2. jcsd
  3. Jul 13, 2010 #2
    Before we can give you help, can you clarify with parentheses what your integrand is? Is it (x5-2x2-1)/(3x4)? I ask, because it is difficult to read the problem and your work without parentheses.
     
  4. Jul 13, 2010 #3

    Mark44

    Staff: Mentor

    Also, when you write stuff like this
    xn dx = xn+1

    n + 1 + C if n is NOT= -1
    x-1 dx = ln|x|+ C​

    it's difficult to discern that xn means xn or that x-1 means x-1. At the very least, use ^ more consistently.
     
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