Is y = sqrt(x) a function?  TOPIC_SOLVED

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Is y = sqrt(x) a function?

Postby jdom543 on Thu Jul 29, 2010 7:32 am

Well is y = sqrt(x) a function?

I understand the definition of a function but I wonder this since when you simply graph y = sqrt(x) in a calculator it only shows the positive y values and will only give the negative ones if you also input y = -sqrt(x).

Shouldn't y=sqrt(x) in reality contain both the positive and negative y values since sqrt give a positive and negative answer?

I assume the calculator only graphs the positive values since that is just how it works. Or when given y=sqrt(x). Are we only supposed to show the positive values unless given -sqrt(x)?

I'm sorry if this post is poorly worded. Hopefully someone will understand what I am saying.
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Postby stapel_eliz on Thu Jul 29, 2010 11:12 am

jdom543 wrote:Shouldn't y=sqrt(x) in reality contain both the positive and negative y values since sqrt give a positive and negative answer?

On what basis did you conclude that, for instance, the square root of four is "both" positive and negative?

Note: Solving x2 = 4 and evaluating sqrt[4] are two very different things! :wink:
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Re: Is y = sqrt(x) a function?  TOPIC_SOLVED

Postby Martingale on Thu Jul 29, 2010 2:50 pm

The calculator only displays the principle square root
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