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!

Need help in determining the lim

  1. Nov 28, 2006 #1

    [tex]\lim_{x\rightarrow 4}\frac{x^2 - 3x + 4}{2x^2 - x - 1}[/tex]

    this is lim x ->4 which is the cube root of the whole fraction ^

    Is there any way to answer this because i cant really factor it....
    Last edited: Nov 28, 2006
  2. jcsd
  3. Nov 28, 2006 #2
    Why not just evaluate the limit at [itex] x = 4 [/itex]?
  4. Nov 28, 2006 #3


    User Avatar
    Science Advisor
    Homework Helper

    You don't need to factor it. It can easily be factored, since it's a ratio of quadratic polynomials.

  5. Nov 28, 2006 #4
    Assuming f(x) is continuous at f(a) ([tex]\lim_{x \rightarrow a^{+}} f(x) = f(a) =\lim_{x \rightarrow a^{-}} f(x)[/tex]) you can always just plug in a. The only time you would need to factor is if f(x) is not continuous at a or if plugging in a would result in an undefined function (0 in denominator). So yea, as courtigrad said, just substitute x=4. :-)
    Last edited: Nov 28, 2006
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Need help in determining the lim
  1. Help with Determinants (Replies: 1)