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Calculus1 28 Online
OpenStudy (anonymous):

Find the derivative with respect to x of the given combination at the given value of x. problem attached

OpenStudy (anonymous):

I'm so confused on how to get this answer.

hartnn (hartnn):

were you able to find derivative of \(\sqrt {g(x)}\) first >

OpenStudy (anonymous):

Yeah, I got \[\sqrt{16}\]

OpenStudy (anonymous):

then I used the d(√u)= u ' / 2 √u formula

OpenStudy (anonymous):

so I thought u' = 1 and u = √16

OpenStudy (anonymous):

i get √16 = 4 * 2 = 8

OpenStudy (anonymous):

but not sure where the 7 comes from :S

hartnn (hartnn):

no, i meant derivative of \(\sqrt {g(x)}\) which will come in terms of x and not constant....

hartnn (hartnn):

use chain rule...

hartnn (hartnn):

you'll also have g'(x) in the numerator...

OpenStudy (stamp):

\[d(\sqrt{g(x)})=\frac{1}{2\sqrt{g(x)}}g'(x)\]

hartnn (hartnn):

yup...now x=3 will give u 7/8 right ?

hartnn (hartnn):

because g'(3)=7

OpenStudy (anonymous):

Yes. I didn't know I had to multiply by g'(x) .

hartnn (hartnn):

now you know :) any doubts ?

OpenStudy (anonymous):

Nope. Thanks for the help :)

hartnn (hartnn):

welcome ^_^

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