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Homework Help: Find the Limit, if it exists.limx→ 2 x^2+7x-18

  1. Jul 17, 2012 #1
    Find the Limit, if it exists.limx→ 2x^2+7x-18

    Find the Limit, if it exists.

    lim
    x→ 2

    x^2+7x-18
    x-2

    I know the answer is 11, but I am confusing myself on how 11 became the answer. My textbook is worthless and I need a dumbed down reason as to how 11 became the answer.

    Thanks
    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
     
  2. jcsd
  3. Jul 17, 2012 #2

    SammyS

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    Re: Limits

    Factor the numerator.

    According to the rules of this Forum, you need to show some effort before we can give much help.
     
  4. Jul 17, 2012 #3

    jbunniii

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    Re: Limits

    I suggest that you start by factoring the polynomial in the numerator. This should be easy because ___ is a root (fill in the blank).
     
  5. Jul 17, 2012 #4
    Re: Limits

    My mistake, I should have not over thought that one.

    factor the polynomial is what I was missing for some reason

    (x+9)(x-2),

    (x-2)'s factor and

    (2+9) is how 11 is formed
     
  6. Jul 17, 2012 #5

    HallsofIvy

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    Re: Limits

    You mean the (x- 2)'s cancel, not "factor". And that is true as long as x is NOT 2. Fortunately, the limit, as x approaches 2, is not dependent upon the value at x= 2.
     
  7. Jul 17, 2012 #6
    Re: Limits

    Thanks for all your help. Pardon my mistakes in wording. I do know the difference in how things are worded is vital to the cumulative world of higher math. I am teaching myself calculus through a textbook and some e-calculus website in hopes of getting familiar with it before entering college again after 8 years in the Marines.

    Love the help and the website.

    Thanks again
     
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