How to show that this function is continuous at 0?

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Homework Help Overview

The discussion revolves around demonstrating the continuity of a function \( f \) at \( 0 \), given the condition \( |f(x)| \leq |x| \) for all real numbers \( x \). Participants are exploring the implications of this inequality and how it relates to the definition of continuity.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the definition of continuity and the need to show that the limit of \( f(x) \) as \( x \) approaches \( 0 \) equals \( f(0) \). There is confusion regarding the handling of absolute values and the implications of the inequality involving \( f(x) \).

Discussion Status

Some participants have attempted to apply the limit definition of continuity and have raised questions about the function's behavior near \( 0 \). There is mention of using the squeeze theorem as a potential approach to demonstrate continuity, indicating a productive direction in the discussion.

Contextual Notes

Participants express uncertainty about the function's representation as part of an inequality and how to effectively utilize this in their arguments. The discussion reflects a need for clarity on the definition of continuity and the properties of the function involved.

nerdz4lyfe
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Homework Statement



For all real numbers, f is a function satisfying |f(x)|<=|x|. Show that f is continuous at 0

Homework Equations





The Attempt at a Solution



Really stuck on this cause I'm confused with the absolute values on this function.

I *think* to show this you have to see if lim x>0+f(x) = lim x>0-f(x) = f(0) ?

And I tried doing this:
-|x|<=f(x)<=|x|
lim x>0+|x|=0
lim x>0- -|x|=0
f(0)=|0|=0
So they're all equal to 0.

I don't know if this is right though...help?
 
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what is the definition of continuous? show that each part of the definition is satisfied by the function and you've shown it is continuous.

If you notice that the slope of f(x) is bounded by the absolute value curve to be: 1>= slope >= -1 on either side of 0
 
Last edited:
That's what I tried to do here.

The definition of a function being continuous at 0 is that lim x>0 f(x) = f(0)
So I tried to show the limit exists if the left and right hand limits are equal. And that this limit also equals f(0).

I guess what I'm more confused about then, is the function itself. I don't know how to deal with the fact that the function is shown as part of an inequality, and with the absolute values
 
nerdz4lyfe said:
That's what I tried to do here.

The definition of a function being continuous at 0 is that lim x>0 f(x) = f(0)
So I tried to show the limit exists if the left and right hand limits are equal. And that this limit also equals f(0).

I guess what I'm more confused about then, is the function itself. I don't know how to deal with the fact that the function is shown as part of an inequality, and with the absolute values

Your work is nearly correct. You can now simply used the squeeze theorem, sandwiching f(x) between -|x| and |x|, so that it does satisfy the continuity definition by getting [itex]\lim_{x\to 0} f(x) = 0[/itex]
 

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