September 14th, 2013, 03:50 AM  #1 
Member Joined: Sep 2012 Posts: 61 Thanks: 0  Limit with cube and square root
How to solve this: lim [cuberoot(7+x^3)squareroot(3+x^2)]/(x1) x>1 I don't know what to do when I have cube and square root at the same time. 
September 14th, 2013, 04:41 AM  #2 
Member Joined: Apr 2013 Posts: 52 Thanks: 0  Re: Limit with cube and square root
Since both the numerator and the denominator equal to zero,when x>1,you can apply the "L'Hospital's Rule",that allows you to evaluate the limit more easily!! :P Are you familiar with this rule,or should I explain it further to you?? 
September 14th, 2013, 05:24 AM  #3 
Member Joined: Sep 2012 Posts: 61 Thanks: 0  Re: Limit with cube and square root
I need to do this without differentiation.

September 15th, 2013, 12:09 AM  #4 
Member Joined: Sep 2012 Posts: 61 Thanks: 0  Re: Limit with cube and square root
Any idea, please?

September 16th, 2013, 08:21 AM  #5 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,949 Thanks: 1141 Math Focus: Elementary mathematics and beyond  Re: Limit with cube and square root
Assuming the limit exists, 
September 16th, 2013, 10:52 AM  #6 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,949 Thanks: 1141 Math Focus: Elementary mathematics and beyond  Re: Limit with cube and square root
I think the limit must exist. Here's why: Reversing the sign of L gives the same result. Hence the limit exists and is equal to 
September 16th, 2013, 11:26 AM  #7 
Member Joined: Sep 2012 Posts: 61 Thanks: 0  Re: Limit with cube and square root
I didn't understand the part I attached. Could you explain more deeply what you did, and with what purpose?

September 16th, 2013, 11:42 AM  #8 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,949 Thanks: 1141 Math Focus: Elementary mathematics and beyond  Re: Limit with cube and square root Ok? 
September 17th, 2013, 07:22 AM  #9 
Member Joined: Sep 2012 Posts: 61 Thanks: 0  Re: Limit with cube and square root
It's okay, thanks.


Tags 
cube, limit, root, square 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
cube root  lila342  Algebra  4  March 6th, 2014 11:57 PM 
Help with Cube Root:  achintya  Algebra  10  April 5th, 2013 10:33 AM 
Cube root of 2  mathmaniac  Algebra  49  March 25th, 2013 05:48 PM 
Limit with square root  Reshi  Calculus  2  October 22nd, 2011 03:24 AM 
Limit Of Square Root  wannabe1  Real Analysis  3  September 30th, 2010 10:40 PM 