Confused? Let's Clarify Homework Solutions!

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Homework Help Overview

The discussion revolves around evaluating a set of mathematical statements related to limits and L'Hospital's rule. Participants are attempting to clarify their understanding of which statements are true or false based on their interpretations of the rules of calculus.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants express confidence in their answers but seek validation, particularly regarding the correctness of specific statements. Questions arise about the application of L'Hospital's rule and the conditions under which it can be used. Some participants are reconsidering their interpretations of certain limits.

Discussion Status

The discussion is ongoing, with participants actively questioning each other's reasoning and interpretations. Some guidance has been offered regarding the conditions necessary for applying L'Hospital's rule, and there is a recognition of potential misunderstandings in the evaluation of specific limits.

Contextual Notes

Participants are working from a visual reference that is not included in the discussion, which may lead to varying interpretations of the statements being evaluated. There is a noted emphasis on the importance of the behavior of functions as they approach certain limits.

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Homework Statement


http://img692.imageshack.us/img692/6661/36979008.jpg


Homework Equations





The Attempt at a Solution


whats wrong with it? I am 100% sure and i can explain each one!
the first one equals 3 right?

second one should be true because 0/0 can be any number.. (thats what my teacher from high school said at least)
 
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Slimsta said:
whats wrong with it? I am 100% sure and i can explain each one!

Then you just answered your own question. :-)
 
clamtrox said:
Then you just answered your own question. :-)

yeah but i guess i think that i know everything but something might be wrong..
and it will take me a long time to write down an explanation for each one :/

is the 3rd one right? i mean, f/g has to be g cannot = 0.. but its not in the lhospital rule...
 
someone please help me
 
What exactly is your question? In your first post you said "im 100% sure and i can explain each one!"

The only question I can find is in your second post, "is the 3rd one right? i mean, f/g has to be g cannot = 0.. but its not in the lhospital rule... " In order that we be able to use L'Hospital's rule directly, we must have \lim_{x\to a} g'(x)\ne 0 and that's impossible if g'(x)= 0 in some neighborhood of a. We might be able to extend L'Hopital's rule in the case that f'/g' goes to 0/0 itself by using L'Hopital's rule again, but in order for that to work eventually, there must be some nth derivative of g which has non-zero limit at x= a but again, that's impossible if there is some neighborhood of a in which g' is 0.
 
HallsofIvy said:
What exactly is your question? In your first post you said "im 100% sure and i can explain each one!"

The only question I can find is in your second post, "is the 3rd one right? i mean, f/g has to be g cannot = 0.. but its not in the lhospital rule... " In order that we be able to use L'Hospital's rule directly, we must have \lim_{x\to a} g'(x)\ne 0 and that's impossible if g'(x)= 0 in some neighborhood of a. We might be able to extend L'Hopital's rule in the case that f'/g' goes to 0/0 itself by using L'Hopital's rule again, but in order for that to work eventually, there must be some nth derivative of g which has non-zero limit at x= a but again, that's impossible if there is some neighborhood of a in which g' is 0.

my question is, which one from the picture above is wrong?
 
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please someone! i checked it over like 20 times now..
1. is 'false' for sure because it limit = 3
2. its a fact so 'true'
3. its a rule so 'true'
4. its part of the rule so 'true'
5. small number / big number = closer and closer to 0 ==> 0 so 'true'
6. limit of infinity = infinity.. :| so 'true'
7. like the 3rd one but in words, so 'true'

whats wrong with it??
 
point 4. g'(x) must be nonzero in some interval that contains c. This should be:
in every interval that contains c, g'(x) can't be zero everywhere in that interval.
 
I would reconsider number 6. Just think about what would happen if \lim_{x \to \infty}f(x) = -\infty.
 
  • #10
jgens said:
I would reconsider number 6. Just think about what would happen if \lim_{x \to \infty}f(x) = -\infty.

those are such small things that both me and 2 of my buddies didnt pick on.. oh man. :|

thanks guys
 

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