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!

Questions about limits.

  1. Mar 25, 2007 #1
    I have 2 questions about limits :

    1)Evaluate : lim as x approaches infinity for
    (3x-4-4x^2) / (x^2 -16)

    2)Evaluate: lim as x approaches -27 for
    (27+x) / ( 7/2 + 3 )

    thank u.
     
  2. jcsd
  3. Mar 25, 2007 #2

    JasonRox

    User Avatar
    Homework Helper
    Gold Member

    If you show us some work, we will be glad to help you.
     
  4. Mar 25, 2007 #3
  5. Mar 25, 2007 #4
    for #1, in order to find the limit as x approaches infinity you need to divide the numerator/denominator by the highest power of x in the denominator, in this problem it would be x^2.
    Doing this you'd end up with some 1/x's or x^n times some constant (1,2,3,...) which =0 when you take their limit as x approaches infinity

    for #2, lim as x approaches a for f(x) = f(a) IF a is in the domain of f
     
    Last edited: Mar 25, 2007
  6. Mar 25, 2007 #5
    For #2, when you plug -27 in you get a number over a nonzero. That means the limit equals the value of the function, in this case, 0
     
  7. Mar 25, 2007 #6
    what about Q.1 i still dont understand how to solve it using infinity???
     
  8. Mar 25, 2007 #7
    In the limit, only the highest degree matters. Because the numerator and denominator have the same degree, the function will have a limit (horizontal asymtote) approaching infinity. Divide the coefficient of the numerator by the coefficient of the denominator and you have all thats left when x is big. Your post is different from your work, but either way the answer should be apparent in 2 seconds
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Questions about limits.
  1. Limit Question (Replies: 35)

  2. Limit question (Replies: 9)

Loading...