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Mathematics 7 Online
OpenStudy (anonymous):

determine the following integral: equation posted next

OpenStudy (anonymous):

\[\int\limits_{}^{}\frac{ e ^{x}+\sec ^{2}x }{ e ^{x}+\tan x }\]

OpenStudy (anonymous):

is it \[\frac{ e ^{x}+\tan x }{ e ^{x}+ \frac{ \cos x }{ sin x } }\]

OpenStudy (anonymous):

anyone?

hartnn (hartnn):

put e^x + tan x = u

OpenStudy (anonymous):

ok done

OpenStudy (dape):

That's not correct. But if you do the substitution @hartnn mentioned it should work out.

hartnn (hartnn):

u get du = e^x +sec^2 x hx which is your numerator.

hartnn (hartnn):

use \(\huge \int \frac{f'(x)}{f(x)}dx=ln|f(x)|+c\)

OpenStudy (anonymous):

oh ().o

hartnn (hartnn):

u get integral of (1/u) du

hartnn (hartnn):

which is ln|u|+c

OpenStudy (anonymous):

I am not understanding this at all. why do you have hx in du = e^x +sec^2 x hx

hartnn (hartnn):

that was typo, sorry du = e^x +sec^2 x dx

OpenStudy (anonymous):

oh ok. so then ln|e^x+tanx|+c?

hartnn (hartnn):

thats it :)

OpenStudy (dape):

Okay, starting from \[ \int{\frac{e^x+\sec^2(x)}{e^x+\tan(x)}dx} \] we do the substitution \(u=e^x+\tan(x)\), and since \(du=(e^x+\sec^2(x))dx\), we get \[ \int{\frac{du}{u}} \] Now if you do that integral and then substitute back, you get your answer.

OpenStudy (anonymous):

lol my brain is asleep today.

OpenStudy (dape):

Which step don't you understand?

OpenStudy (anonymous):

nope got it now dape

OpenStudy (dape):

Okay :)

OpenStudy (anonymous):

but i have got another question about integrals

OpenStudy (dape):

Go ahead

OpenStudy (anonymous):

ill post a new one

hartnn (hartnn):

@ANTOINETTEs post that as a new question. not in comments.......

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