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Mathematics 17 Online
OpenStudy (anonymous):

Differentiation problem, please help!

OpenStudy (anonymous):

Yes

OpenStudy (anonymous):

Suppose \[\sqrt{x}+\sqrt{y}=1\]. Find y''

OpenStudy (anonymous):

I found f' already, which I got \[\frac{ -\sqrt{y} }{ \sqrt{x} }\] for, is that right so far?

OpenStudy (anonymous):

Yes But Hold On Im Working It

OpenStudy (ash2326):

Yes. You are right @stottrupbailey

OpenStudy (anonymous):

Thank you :) So I'm confused about the next step though

OpenStudy (ash2326):

What do you have to do next?

OpenStudy (anonymous):

quotient rule, right?

OpenStudy (ash2326):

yes. do you have to find f''?

OpenStudy (anonymous):

yes

OpenStudy (ash2326):

Did you try?

OpenStudy (anonymous):

yes, this is what I have so far\[\frac{ \frac{ -\sqrt{x} }{ 2\sqrt{y} }\frac{ dy }{ dx } +\frac{ \sqrt{y} }{ 2\sqrt{x} } }{ x }\]

OpenStudy (anonymous):

I'm just confused about getting dy/dx by itself because this isn't an equation, so I can't subtract and multiply stuff over.

OpenStudy (ash2326):

substitute \[\frac{dy}{dx}=-\frac{\sqrt y}{\sqrt x}\]

OpenStudy (anonymous):

Oh, I see, okay just a sec

OpenStudy (anonymous):

so is the answer \[\frac{ \sqrt{x}+\sqrt{y} }{ 2x \sqrt{x} }\] ?

OpenStudy (anonymous):

I get this finally \[\frac{ d^{2}y }{ dx^{2}}=\frac{ -x^{\frac{ -3 }{ 2 }}-2x^{\frac{ -1 }{ 2 }} }{ y^{\frac{ -3 }{ 2 }} }\]

OpenStudy (ash2326):

@stottrupbailey yes you are right

OpenStudy (anonymous):

Thanks so much ash2326! :)

OpenStudy (ash2326):

you're welcome :D

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