Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

cwrw238

I continue to have trouble solving limits in calculus. Can anybody recommend a good website which deals with this. An 'idiots guide' ?

  • one year ago
  • one year ago

  • This Question is Closed
  1. ParthKohli
    Best Response
    You've already chosen the best response.
    Medals 1

    1) People who are not idiots don't need an idiots' guide. 2) http://tutorial.math.lamar.edu/

    • one year ago
  2. cwrw238
    Best Response
    You've already chosen the best response.
    Medals 0

    lol - thank you parthkohli - i'll take a look

    • one year ago
  3. agentc0re
    Best Response
    You've already chosen the best response.
    Medals 1

    You're not an idiot. Limits are tricky business. What kind of limits are you having trouble with? Limits approaching infinity? Zero? or some other finite #?

    • one year ago
  4. cwrw238
    Best Response
    You've already chosen the best response.
    Medals 0

    i think limits approaching 0 and infinity

    • one year ago
  5. agentc0re
    Best Response
    You've already chosen the best response.
    Medals 1

    Limits approaching infinity have 3 "rules" to make this a bit more simple. \[\lim_{x \rightarrow \infty} {x^4+123x^3-x^2-238x+10^6 \over 34x^4-38x+11}\] \[\lim_{x \rightarrow \infty} {x^4+123x^3-x^2-238x+10^6 \over 34x^5-38x+11}\] \[\lim_{x \rightarrow \infty} {x^7+123x^3-x^2-238x+10^6 \over 34x^4-38x+11}\] Lets just talk about what we see going on here. Can you tell me what you notice in the first example? (besides that it looks like a mess :D )

    • one year ago
  6. cwrw238
    Best Response
    You've already chosen the best response.
    Medals 0

    well - the degree of top and bottom poly's are the same

    • one year ago
  7. cwrw238
    Best Response
    You've already chosen the best response.
    Medals 0

    sorry i didn't answer earlier - i was called away

    • one year ago
  8. agentc0re
    Best Response
    You've already chosen the best response.
    Medals 1

    It's no problem. And you're correct. The degree of the polynomials are the same on top and bottom. So lets let this rule be our first. If the highest degree polynomials are the same in the denominator as in the numerator, then the limit as it approaches infinity will ALWAYS be the ration of the coefficients. In this case that ratio is \[1\over34\] The reason why this is is if you multiplied the entire equation by \[{1 \over x^4}\over{1 \over x^4 }\] We would then have a lot of cases were there would be some number divided by some form of x. \[1 \over x\] for x= infinity will always go to zero. So on top you would just have 1 + 0 - 0 - 0 + 0 and on bottom you would have 34 - 0 +0 Does that help with the first example? Any questions?

    • one year ago
  9. cwrw238
    Best Response
    You've already chosen the best response.
    Medals 0

    thanks - no questions - thats very clear

    • one year ago
  10. agentc0re
    Best Response
    You've already chosen the best response.
    Medals 1

    Awesome!!! Lets go to example two. What do you notice there?

    • one year ago
  11. cwrw238
    Best Response
    You've already chosen the best response.
    Medals 0

    the denominator has higher degree

    • one year ago
  12. agentc0re
    Best Response
    You've already chosen the best response.
    Medals 1

    Right. Do you have a guess as to what might happen?? ... shoot i have to go and i don't want to leave you hanging. A good video about this is: http://patrickjmt.com/limits-at-infinity-basic-idea-and-shortcuts-for-rational-functions/ WHen i get back i can help further explain what's going on if the video doesn't help.

    • one year ago
  13. cwrw238
    Best Response
    You've already chosen the best response.
    Medals 0

    do we multiply top and bottom by 1 /x^5 ?

    • one year ago
  14. agentc0re
    Best Response
    You've already chosen the best response.
    Medals 1

    For the second example, multiple the top and bottom in the same way we did the first one but do it by the highest degree polynomial. You see that you get 0/(some number). therefor these types of limits when approaching infinity ALWAYS go to zero! how awesome is that?

    • one year ago
  15. cwrw238
    Best Response
    You've already chosen the best response.
    Medals 0

    yea awesome is right

    • one year ago
  16. cwrw238
    Best Response
    You've already chosen the best response.
    Medals 0

    thanks

    • one year ago
  17. cwrw238
    Best Response
    You've already chosen the best response.
    Medals 0

    ill take a look at the video

    • one year ago
  18. agentc0re
    Best Response
    You've already chosen the best response.
    Medals 1

    I'm back! :D did you have questions still about limits approaching infinity?

    • one year ago
  19. cwrw238
    Best Response
    You've already chosen the best response.
    Medals 0

    no - i'm checking out the video which is very good. thanks very much for your help

    • one year ago
  20. ParthKohli
    Best Response
    You've already chosen the best response.
    Medals 1

    Also, not to forget mentioning http://khanacademy.com

    • one year ago
  21. cwrw238
    Best Response
    You've already chosen the best response.
    Medals 0

    @parthkohi oh right - thanks

    • one year ago
  22. ParthKohli
    Best Response
    You've already chosen the best response.
    Medals 1

    You're welcome. Can you please give the medal to @agentc0re? He deserves it all. (:

    • one year ago
    • Attachments:

See more questions >>>

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.