HP 50g Limit Help

02232017, 05:59 AM
Post: #1




HP 50g Limit Help
Greetings everyone!
I cannot get my HP 50g to find the limit as X approaches 0 when... f(x)=(cos(x)1+(1/2)*x^2)/x^4. When I try to solve it on the calculator, regardless if in AOS or RPN, I always get the response "Insufficient order" from the calculator and puts a "?" as my answer. I know the problem has an answer because I solved it by hand. The answer is 1/24. I have been able to find every limit I have encountered with my HP 50g until now so this is a very unexpected problem that surfaced. I have spent about 30 minutes trying to figure it out but came out with nothing. Therefore, I am hoping I can count on everyone's help here at the Museum, especially since I don't have anymore time to spend on this issue. (College. Need I say more?). Plus, it's getting rather frustrating but I just got to keep remembering that it's problems like these that makes me learn more about my HP 50g. Thank you all so much in advance! 

02232017, 01:12 PM
Post: #2




RE: HP 50g Limit Help
Hi!
The default order used by lim is less than 4, so it is too low for your example. Put your function on stack level 3, 'X=0' on level 2, and the required order (4 at least) on level 1, then execute SERIES, instead of lim. Best regards. 

02232017, 02:14 PM
Post: #3




RE: HP 50g Limit Help
as suggested by Pascal:
'(COS(X)1+X^2/2)/X^4' 'X=0' 4 SERIES > { :Limit: '1/24' :Equiv: '1/24' :Expans: '1/24' :Remain: h } 'h=X' so '1/24' is the answer 

02232017, 05:41 PM
Post: #4




RE: HP 50g Limit Help
(02232017 05:59 AM)Carsen Wrote: I cannot get my HP 50g to find the limit as X approaches 0 when... A little off topic, but my HP Prime came out with the correct answer on both environments (Home and CAS), by just typing your function. I know it's not a RPL machine and it doesn't have the 50G heritage, but it's a HP as well and highly oriented to the education market. Jose Mesquita RadioMuseum.org member 

02232017, 06:32 PM
Post: #5




RE: HP 50g Limit Help
Pascal and Simone! Thanks so much! It worked perfectly the first time I tried it out. But now I have one more question in the functionality of the SERIES function. I do not understand the concept of the "order" that you put on level 1 of the stack before executing the function SERIES. How do I know what number of order to use? Keep in mind that I have not learned anything about Taylor Polynomials and I don't know too much about limits yet. I am only in Calculus 2.
Jebem. Yeah, I would LOVE to get a Prime mainly for it's touchscreen because it is so useful when graphing. But I am thinking of getting a HP 48gx first while I can because there are only so many of them left out there. Plus, I don't have too much of a budget for buying calculators...yet Again, Thank you all for helping me out! 

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