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Limits help

  1. Oct 15, 2005 #1
    can anybody help me with these two question for finding limits:

    1. lim h -> 0 ((3+h)^-1 - 3^-1)/h
    2. lim x -> -4- |x+4|/x+4


    please help
     
  2. jcsd
  3. Oct 15, 2005 #2

    shmoe

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    1. looks an awful lot like the kind of limit you find in the definition of the derivative. If you haven't seen derivatives yet (or even if you have) try finding a common demoninator to simplify (3+h)^(-1) - 3^(-1)

    2.you're interested in values of x that are less than -4. Use this to simplify the absolute value.
     
  4. Oct 15, 2005 #3
    for number one if I make it so that I only have positive exponents and simplify I end up with

    1 /(9 + 3h) now if I plug in 0 the result is 1 / 9. Is this correct?
     
  5. Oct 15, 2005 #4

    Math Is Hard

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    I think you might have a sign error. Check this step in the numerator and tell me what you think:
    (3-(3+h))/(9 + 3h) should distribute as (3-3-h)/(9 + 3h) or -h/(9 +3h)
     
  6. Oct 15, 2005 #5
    yeah it looks like I did make an error should be -1/9? right?
     
  7. Oct 15, 2005 #6

    Math Is Hard

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    That's what I got, but maybe one of the local mathletes will stop by and verify. :smile:
     
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