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Homework Help: FInding domains of ln problems

  1. Jun 20, 2011 #1
    1. The problem statement, all variables and given/known data

    How do you find the domain of y=ln(6-x) ?

    3. The attempt at a solution

    do i have to set 6-x greater than or equal to 0 to then get that x is less than or equal to 6, or is there more to it than that? I'm confused on where the ln part comes in. Please assist.
  2. jcsd
  3. Jun 20, 2011 #2
    There isn't more to it, but you made a mistaking setting it to "or equal to zero", since zero is not in it's domain.
    6-x>0 <--> 6>x
    can also be written ]-inf;6[

    The ln part is why we set condition that it is over 0, we need knowledge of the function to determine that.
    Last edited: Jun 20, 2011
  4. Jun 20, 2011 #3
    just what i needed. thank you!
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