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Mathematics 16 Online
OpenStudy (anonymous):

How about this.. Integration

ganeshie8 (ganeshie8):

split it into two terms

OpenStudy (anonymous):

you mean.. 2/e^x and e^x/e^x

ganeshie8 (ganeshie8):

exactly!

OpenStudy (anonymous):

it would be 2e^-x + 1 +C?

ganeshie8 (ganeshie8):

\[\large \int \dfrac{2+e^x}{e^x}~dx\]

ganeshie8 (ganeshie8):

\[\large \int \dfrac{2}{e^x}+\dfrac{e^x}{e^x} ~dx\]

ganeshie8 (ganeshie8):

\[\large \int 2e^{-x}+1~dx\]

ganeshie8 (ganeshie8):

integrate now..

OpenStudy (anonymous):

okay =) wait

OpenStudy (anonymous):

i got 2e^-x +x +c

ganeshie8 (ganeshie8):

small mistake, whats the integral of \(\large \int e^{-x} dx\) ?

OpenStudy (anonymous):

-e^x

ganeshie8 (ganeshie8):

so.. ?

OpenStudy (anonymous):

its -2e^x +x +c

ganeshie8 (ganeshie8):

Yes !

ganeshie8 (ganeshie8):

good job :)

OpenStudy (anonymous):

Thank you so much!!

OpenStudy (anonymous):

wait @ganeshie8

ganeshie8 (ganeshie8):

yes

OpenStudy (anonymous):

how do i solve this one?

ganeshie8 (ganeshie8):

hey wait a sec, for the previous problem, you got its -2e^(-x) +x +c right ?

OpenStudy (anonymous):

-2e^x +x

ganeshie8 (ganeshie8):

nope, and who ate the C ?

ganeshie8 (ganeshie8):

\[\large \int 2e^{-x}+1~dx\] \[\large - 2e^{-x}+x + C\]

OpenStudy (anonymous):

ah. missed the C. hahaha

ganeshie8 (ganeshie8):

thats the final answer ^^

OpenStudy (anonymous):

=)

ganeshie8 (ganeshie8):

for the next problem, substitute \(\large u = \dfrac{\pi}{x}\)

OpenStudy (anonymous):

so the derivative would be -pi/x^2?

ganeshie8 (ganeshie8):

yes!

OpenStudy (anonymous):

and im lost hahaha

ganeshie8 (ganeshie8):

\[\int \dfrac{1}{x^2} \sin \left(\frac{\pi}{x}\right) ~dx\]

ganeshie8 (ganeshie8):

what do you get after making the substitution ?

OpenStudy (anonymous):

really have no idea..

ganeshie8 (ganeshie8):

sub \(\large u = \frac{\pi}{x} \) \(\large du = -\frac{\pi}{x^2}dx\) \(\large -\frac{du}{\pi} = \frac{1}{x^2}dx\)

ganeshie8 (ganeshie8):

substitute these

ganeshie8 (ganeshie8):

\[\int \sin \left(u \right) ~\left(-\frac{du}{\pi}\right)\]

ganeshie8 (ganeshie8):

\[-\frac{1}{\pi}\int \sin \left(u \right) ~du \]

OpenStudy (anonymous):

okay, im following..

ganeshie8 (ganeshie8):

goo, integrate ^

OpenStudy (anonymous):

that would be -1/pi cos pi/x +c?

ganeshie8 (ganeshie8):

whats the integral of sinx ?

OpenStudy (anonymous):

its cosx

ganeshie8 (ganeshie8):

really sure ?

OpenStudy (anonymous):

-cosx

OpenStudy (anonymous):

+c

ganeshie8 (ganeshie8):

yes ! so whats the final answer

OpenStudy (anonymous):

1/pi - cos pi/x +c

OpenStudy (anonymous):

@ganeshie8 i need to go. its already 12am here. i need to refresh everything. Thank you so much!! =)) Goodnight

ganeshie8 (ganeshie8):

\[-\frac{1}{\pi}\int \sin \left(u \right) ~du\] \[-\frac{1}{\pi}( - \cos \left(u \right) ) + C\] \[ \frac{1}{\pi} \cos \left(u \right) + C\]

ganeshie8 (ganeshie8):

good luck !!

ganeshie8 (ganeshie8):

and have good sleep :)

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