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Mathematics 19 Online
OpenStudy (anonymous):

For what interval is the function f(x) = (20 + \sqrt{x}) / (\sqrt{20 + x}) continuous?

OpenStudy (jamesj):

Well, first was is the domain of this function?

OpenStudy (jamesj):

what is

OpenStudy (anonymous):

The domain of this function is [-20, infinity)

OpenStudy (jamesj):

No, it's not.

OpenStudy (anonymous):

No sorry

OpenStudy (anonymous):

The domain it is: (-20,0]

OpenStudy (jamesj):

Noo....

OpenStudy (anonymous):

What?#$

OpenStudy (anonymous):

Then what would it be? This is why I think it is that: The domain of the numerator is [0, infinty) The domain of the denominator is (-20, infinity) The intersection of these two domains is (-20,0]

OpenStudy (jamesj):

The intersection of the two domains is [0, infinity)

OpenStudy (anonymous):

Why?

OpenStudy (jamesj):

Is -1 in both domains? Is -10 in both domains?

OpenStudy (jamesj):

But is 1 in both domains?

OpenStudy (anonymous):

for x greater than zero

OpenStudy (anonymous):

Oh I see. It makes sense because the square root of x only accepts positive real numbers.

OpenStudy (anonymous):

yes

OpenStudy (jamesj):

And zero, yes.

OpenStudy (jamesj):

Now, where is it continuous?

OpenStudy (anonymous):

for every x greater than zero it will be continuous not at any specific point

OpenStudy (anonymous):

Yes I understand, please help me out with my other question.

OpenStudy (turingtest):

@sumbul What to you mean "not at any specific point"?

OpenStudy (anonymous):

in full interval

OpenStudy (turingtest):

the answer is [0,infty) so every x greater-than or equal-to zero

OpenStudy (zarkon):

it is continuous at 0

OpenStudy (jamesj):

oh, you're right.

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