Lim x→0 (x + (1/x)) sin(x) Undefined

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Discussion Overview

The discussion revolves around the limit of the expression (x + (1/x)) sin(x) as x approaches 0. Participants explore the behavior of the components of the expression and the implications for the overall limit, considering both theoretical and mathematical reasoning.

Discussion Character

  • Exploratory
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant suggests that as x approaches 0, 1/x tends towards infinity, leading to the conclusion that (x + (1/x)) approaches infinity, while sin(x) approaches 0, creating an indeterminate form of infinity times zero.
  • Another participant breaks down the expression into two parts, proposing that if each part has a limit as x approaches 0, the limit of their sum can be determined.
  • A subsequent reply calculates the limits of the individual components, concluding that the limit of the original expression is 1, though this conclusion is not universally accepted.
  • One participant mentions using L'Hôpital's rule to analyze the second part of the expression, indicating an alternative approach to resolving the limit.

Areas of Agreement / Disagreement

Participants express differing views on the limit of the original expression, with some supporting the conclusion that it approaches 1, while others highlight the indeterminate form and the need for further analysis. The discussion remains unresolved regarding the overall limit.

Contextual Notes

There are unresolved assumptions regarding the behavior of the components of the expression and the application of limit laws. The discussion also reflects varying interpretations of the indeterminate form presented.

Dr-NiKoN
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lim_x->0 (x + (1/x) ) sin(x)

As x goes towards 0, wouldn't 1/x go towards inf?
Thus
(x + (1/x)) should go towards inf as x goes towards 0?

sin(x) will go towards 0 as x goes towards 0, since sin(0) is 0.

Wouldn't that leave inf * 0 = undefined (or 0)?
 
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Note that your expression is the sum of two other expressions:
(x+\frac{1}{x})\sin(x)=x\sin(x)+\frac{\sin(x)}{x}
1. If it can be shown that each of these expressions (on the right-hand side) has a limit as x->0, what's then true about the limit of their sum (i.e, your original expression)?
 
lim_x->0 f(x) = x*sinx = 0
lim_x->0 g(x) = sinx/x = 1

lim_x->0 f(x) + g(x) = 0 + 1

lim_x->0 (x + 1/x))sinx = 1

Hm, that was a lot easier than I thought, thanks a lot :)

Edit: How do you do latex?
test:
\pi

nevermind :)
 
ah, just l'hopital the second part :-)
 

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