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Homework Help: One sided limit

  1. Sep 9, 2008 #1
    1. The problem statement, all variables and given/known data
    lim[tex]_{x\rightarrow4^{-}}[/tex] [tex]\frac{\sqrt{x}-2}{x-4}[/tex]


    2. Relevant equations
    Typical methods used in solving one-sided limit.


    3. The attempt at a solution
    I plug in something a little bit bigger than four, like 4.0000001 into x, and I get [tex]\frac{something a little less than zero}{something a little less than zero}[/tex] to equal 1. But the answer is 1/4. How is this so?
     
  2. jcsd
  3. Sep 9, 2008 #2
    Multiply both the top and the bottom by [tex]\sqrt{x}+2[/tex]. This is called "multiplying by the conjugate" and is pretty standard for dealing with limits involving square roots
     
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