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Mathematics 5 Online
OpenStudy (anonymous):

Differentiate the inverse trig function.

OpenStudy (anonymous):

\[\sqrt{x^2-1}arcsecx\]

hartnn (hartnn):

product rule (uv), aware of that ?

OpenStudy (anonymous):

yes, but the sqrt(x^2-1), does that need to be chain ruled somehow?

hartnn (hartnn):

yup, chain rule is required there

OpenStudy (anonymous):

\[\sqrt{x^2-1}(\frac{ 1 }{x \sqrt{x^2-1} })+\sec^{-1}(\frac{ 1 }{ 2 }(x^2-1))^{-1/2}\]

OpenStudy (anonymous):

that cant be right

OpenStudy (anonymous):

so, if i chain rule

hartnn (hartnn):

what did u do in 2nd term ?

hartnn (hartnn):

1st term is correct, and u can cancel something there, what ?

OpenStudy (anonymous):

\[\frac{ 1 }{ 2 }(x^2-1)^{-1/2}(\sqrt{x^2-1})(\frac{ 1 }{ x \sqrt{x^2-1} }) + arcsecx \frac{ 1 }{ 2 }(x^2-1)^{-1/2}\]

OpenStudy (anonymous):

is that the chain rule?

hartnn (hartnn):

no...

hartnn (hartnn):

first , did u apply product correctly?

OpenStudy (anonymous):

fg'+gf'

OpenStudy (anonymous):

f = sqrt(x^2-1) g=arcsecx

hartnn (hartnn):

g= arcsec x right ?

hartnn (hartnn):

ok, so what is fg' = ?

OpenStudy (anonymous):

\[\sqrt{x^2-1}(\frac{ 1 }{ x \sqrt{x^2-1} })\]

hartnn (hartnn):

can u cancel something ?

OpenStudy (anonymous):

which is 1/x

hartnn (hartnn):

yes! to be precise its 1/|x| so now you are completely done with fg' it equals 1/|x| now what is gf' ?

OpenStudy (anonymous):

\[arcsecx(\frac{ 1 }{ 2 }(x^2-1))^{-1/2}(2)\]

OpenStudy (anonymous):

chain rule ok?

hartnn (hartnn):

2 or 2x in the end ?

hartnn (hartnn):

yes, chain rule applied correctly. but d/dx(x^2-1) is 2 or 2x ??

OpenStudy (anonymous):

oh 2x my bad

OpenStudy (anonymous):

:0

hartnn (hartnn):

now put everything together fg'+f'g =?

hartnn (hartnn):

remember to cancel 2 from numerator and denominator of 2nd term

OpenStudy (anonymous):

\[\frac{ 1 }{ |x| }+\frac{ 2xarcsecx }{ 2\sqrt{x^2-1} }\]

hartnn (hartnn):

*2 can be cancelled*

OpenStudy (anonymous):

oh ya duh :)

hartnn (hartnn):

so, did u get your required final answer ?

OpenStudy (anonymous):

\[\frac{\sqrt{x^2-1}+xarcsecx }{ x \sqrt{x^2-1} }\]

hartnn (hartnn):

wouldn't it be x^2 in numerator ? before arc.... you could have left it in 2 terms form also

OpenStudy (anonymous):

oh ya, so its x^2arcsecx

OpenStudy (anonymous):

forgot to cross multiply the x

OpenStudy (anonymous):

is that it though?

hartnn (hartnn):

yup, thats it.

OpenStudy (anonymous):

!!!!!

OpenStudy (anonymous):

@hartnn you saved the day yet again!!! :)

hartnn (hartnn):

as usual...welcome ^_^

OpenStudy (anonymous):

\[\frac{ \sqrt{x^2-1}+x^2arcsecx }{ x \sqrt{x^2-1} }\]

hartnn (hartnn):

yup.

OpenStudy (anonymous):

weeew! thanks so much!!!

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