1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Why eliminate answers?

  1. May 31, 2008 #1
    [SOLVED] Why eliminate answers?

    In my book, Essential Calculus, a section is introduced with limits. They introduce a random(maybe) function :

    [tex]Q(h) = \frac {2h + h^2}{h} (h \neq 0)[/tex]

    "We then divide the numerator by the denominator h, which is permissible since [tex]h \neq 0[/tex]. This gives the simple formula [tex]Q(h) = 2 + h (h \neq 0)[/tex]"

    I was always told you do not divide by variables like in a trigonometric equation because it eliminates solutions. How are they then to say that it is permissible since [tex]h \neq 0[/tex] ? I don't understand.
  2. jcsd
  3. May 31, 2008 #2
    In this case, it is fine. Given that [tex]h \neq 0[/tex], both functions are equal because you are only simplifying the function.
  4. May 31, 2008 #3


    User Avatar
    Science Advisor
    Homework Helper

    Hi razored! :smile:

    It's ok because all these calculus equations begin "lim as h -> 0".

    So it's impossible for h to be 0. :smile:

    (oh … and look up L'Hôpital's Rule :wink:)
  5. Jun 1, 2008 #4


    User Avatar
    Staff Emeritus
    Science Advisor

    What "solutions" do you mean? You are not "solving" an equation here.
  6. Jun 1, 2008 #5
    Whoops. That is what I misunderstood. Thanks for pointing that out!
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Why eliminate answers?
  1. Eliminating y (Replies: 15)

  2. Gaussian Elimination (Replies: 3)

  3. Eliminating Parameters (Replies: 1)