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Mathematics 7 Online
OpenStudy (anonymous):

find the derivative of the following function

OpenStudy (anonymous):

\[y=\frac{ 3+2x-8\sqrt{x} }{ x }\]

terenzreignz (terenzreignz):

Just quotient rule away :) \[\huge \frac{d}{dx}\frac{f(x)}{g(x)}=\frac{f'(x)g(x)-f(x)g'(x)}{[g(x)]^2}\]

OpenStudy (anonymous):

or , easier ... bring x from the denominator to the top as x^-1

OpenStudy (anonymous):

divide

OpenStudy (anonymous):

y=3x^-1+2 -8x^(-1/2)

OpenStudy (anonymous):

what?

terenzreignz (terenzreignz):

I reckon it is easier, after all. \[\Large \frac{3+2x-8\sqrt{x}}{x}=\frac3x+2-\frac8{\sqrt{x}}=3x^{-1}+2-8x^{-\frac12}\] And just power rule away, this time :) \[\huge \frac{d}{dx}ax^n=nax^{n-1}\]

OpenStudy (anonymous):

idk any of the rules, I'm taking calculus online and the teacher doesn't help with or explain anything.

terenzreignz (terenzreignz):

Well, the gist of it is, when the derivative of \[\huge ax^n\]You just bring down the exponent n, and multiply it to ax, and then, subtract one from the original exponent \[\huge nax^{n-1}\] For example, the derivative of 4x^3 \[\huge \frac{d}{dx}4x^3=3\cdot4x^{3-1}=12x^2\]Simple :)

OpenStudy (anonymous):

that's the only thing I understand, all the other rules make no sense though

terenzreignz (terenzreignz):

Well, for now, that's all you're going to need, since you're only tasked to differentiate \[\Large 3x^{-1}+2-8x^{-\frac12}\]

OpenStudy (anonymous):

\[3x ^{-2}+4x\]

terenzreignz (terenzreignz):

Almost... but, why is it 4x?

OpenStudy (anonymous):

\[4x ^{-\frac{ 3 }{ 2 }}\] ?

terenzreignz (terenzreignz):

Much better :)

OpenStudy (anonymous):

so that's the answer?

terenzreignz (terenzreignz):

with the 3x^(-2), it is

OpenStudy (anonymous):

Thank you!

terenzreignz (terenzreignz):

No problem.

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