Results 1 to 4 of 4

Math Help - Indeterminate Limits, Help! lol

  1. #1
    Newbie
    Joined
    Sep 2008
    Posts
    2

    Indeterminate Limits, Help! lol

    I've got a HW problem I just cannot figure out. Can someone please explain how to solve this. I know it is a indeterminate limit and I was told to use algebraic laws to solve it, but my algebra is a little rusty.

    Lim x->4 ( ( 1/sqrt(x)-2 ) - ( 4/x-4 ) ) ?
    I know the answer is 1/4, but have no idea how that is the answer.

    also,

    Lim x->0 ( ( 3^(2x)-1 ) / ( 3^(x) -1 ) )

    Thank you to anyone can help me with these two problems!
    Last edited by gandrade3; September 10th 2008 at 08:10 AM. Reason: Edited for equation 1.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Moo
    Moo is offline
    A Cute Angle Moo's Avatar
    Joined
    Mar 2008
    From
    P(I'm here)=1/3, P(I'm there)=t+1/3
    Posts
    5,618
    Thanks
    6
    Hello,
    Quote Originally Posted by gandrade3 View Post
    I've got a HW problem I just cannot figure out. Can someone please explain how to solve this. I know it is a indeterminate limit and I was told to use algebraic laws to solve it, but my algebra is a little rusty.

    Lim x->4 ( ( 1/sqrt(2)-2 ) - ( 4x-4 ) )?
    I know the answer is 1/4, but have no idea how that is the answer.
    huh ?
    Is it \lim_{x \to 4} \frac{\frac{1}{\sqrt{2}}-2}{4x-4} ?


    also,

    Lim x->0 ( ( 3^(2x)-1 ) / ( 3^(x) -1 ) )

    Thank you to anyone can help me with these two problems!
    Note that 3^{2x}=(3^x)^2

    now you have a difference of squares in the numerator. So factorise
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Sep 2008
    Posts
    2
    No, sorry about the confusion. I was in a rush and made some mistakes on the first.

    Lim x->4 ( ( 1/sqrt(x)-2 ) - ( 4/x-4 ) )

    I forgot to put the division sign between 4 and x-4. (1/sqrt(x)-2) and (4/x-4) are subtracted by each other.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Moo
    Moo is offline
    A Cute Angle Moo's Avatar
    Joined
    Mar 2008
    From
    P(I'm here)=1/3, P(I'm there)=t+1/3
    Posts
    5,618
    Thanks
    6
    Quote Originally Posted by gandrade3 View Post
    No, sorry about the confusion. I was in a rush and made some mistakes on the first.

    Lim x->4 ( ( 1/sqrt(x)-2 ) - ( 4/x-4 ) )

    I forgot to put the division sign between 4 and x-4. (1/sqrt(x)-2) and (4/x-4) are subtracted by each other.
    Sorry, I misread and put a division sign instead of -.

    Multiply the first fraction by \frac{\sqrt{x}+2}{\sqrt{x}+2} ( {\sqrt{x}+2} is the conjugate of {\sqrt{x}-2})

    Then you'll have to be careful, take 2 situations :
    - x \to 4 and x>4
    - x \to 4 and x<4
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. please help with limits of indeterminate forms
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: March 19th 2009, 07:18 PM
  2. limits indeterminate form
    Posted in the Calculus Forum
    Replies: 3
    Last Post: November 8th 2007, 06:13 PM
  3. Limits & Indeterminate Forms
    Posted in the Calculus Forum
    Replies: 10
    Last Post: October 25th 2007, 01:47 PM
  4. LImits at infinity help: Indeterminate forms
    Posted in the Calculus Forum
    Replies: 8
    Last Post: March 11th 2007, 09:02 AM
  5. Indeterminate Forms: Limits infinite... help
    Posted in the Calculus Forum
    Replies: 3
    Last Post: March 4th 2007, 04:06 AM

Search Tags


/mathhelpforum @mathhelpforum