Epsilon-delta proof of sqrt of abs value of x

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In summary, an epsilon-delta proof is a mathematical technique used to rigorously prove the limit of a function by using two variables, epsilon and delta. It is particularly useful for functions that are not continuous, such as the square root of the absolute value of x, as it allows for a more precise and rigorous proof. Epsilon and delta are chosen based on the desired level of precision, with epsilon representing the distance between the limit and the actual output of the function, and delta representing the distance between the input and the desired input value. While epsilon-delta proof can be used for any function, it may be more challenging for complex or nonlinear functions. To write an epsilon-delta proof for the square root of the absolute value of x
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kahwawashay1
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Prove that the limit as x->0 of [itex]\sqrt{\left|x\right|}[/itex] = 0

attempt:

[itex]\sqrt{\left|x\right|}[/itex] < [itex]\epsilon[/itex] when |x|<[itex]\delta[/itex]

-[itex]\epsilon[/itex] < [itex]\sqrt{\left|x\right|}[/itex] < [itex]\epsilon[/itex]

[itex]\left|x\right|[/itex] < [itex]\epsilon[/itex][itex]^{2}[/itex]

[itex]\delta[/itex]=[itex]\epsilon[/itex][itex]^{2}[/itex]

This seems to work...but I just ignored the negative epsilon since I can't square it in my inequality...I don't know if you are allowed to just ignore this?
 
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[tex]
\sqrt{|x|} < \epsilon \Leftrightarrow |x| < \epsilon^{2}
[/tex]

If you choose a [itex]\delta[/itex] such that:
[tex]
0 < \delta < \epsilon^2
[/tex]
you are done.
 

FAQ: Epsilon-delta proof of sqrt of abs value of x

What is an epsilon-delta proof?

An epsilon-delta proof is a mathematical technique used to rigorously prove the limit of a function. It involves using two variables, epsilon and delta, to show that as the input of the function approaches a certain value, the output also approaches a specific value.

Why is epsilon-delta proof used for the square root of the absolute value of x?

The square root of the absolute value of x is a function that is not continuous at x=0. Therefore, a traditional limit proof using algebraic manipulation is not sufficient. Epsilon-delta proof allows for a more rigorous and precise proof for this type of function.

How do you choose the values for epsilon and delta in an epsilon-delta proof?

Epsilon and delta are typically chosen based on the desired level of precision in the proof. Epsilon represents the distance between the limit and the actual output of the function, while delta represents the distance between the input and the desired input value.

Can epsilon-delta proof be used for any function?

Yes, epsilon-delta proof can be used for any function, as long as the function is defined and continuous at the desired input value. However, it may be more challenging to use for more complex or nonlinear functions.

How do you write an epsilon-delta proof for the square root of the absolute value of x?

An epsilon-delta proof for the square root of the absolute value of x involves setting up the inequalities |x-a|

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