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Mathematics 17 Online
OpenStudy (dls):

Integrate

OpenStudy (dls):

\[\Huge \int\limits_{}^{} \sin x . e^x\]

OpenStudy (anonymous):

You want step-wise solution or just answer?

OpenStudy (dls):

I'm caught in an infinite loop using by parts

OpenStudy (dls):

\[\Huge \sin x \int\limits_{}^{} e^x - \int\limits_{}^{} [\cos x \int\limits_{}^{} e^x]\]

OpenStudy (dls):

\[\Huge \sin x. e^x - \int\limits\limits_{}^{} [\cos x . e^x]dx\]

OpenStudy (anonymous):

\[\large =\sin x e^x-\int e^x\cos x\\ \large \sin x e^x -(e^x\sin x-\int e^x (-\sin x))\] using by parts again

OpenStudy (dls):

i got the basic idea of what you're gonna do,that changes to I

OpenStudy (anonymous):

now if we let \[\int e^x \sin x=I\] \[I=e^x \sin x-e^x\cos x-I\] \[I=\frac{e^x}{2}(\sin x-\cos x)\]

OpenStudy (dls):

nice :O

OpenStudy (anonymous):

previusly i made a mistake by using sin x instead of cos x

OpenStudy (dls):

yeah,spotted that one

zepdrix (zepdrix):

Ooo this is a fun integral :D

OpenStudy (dls):

yeah :P

OpenStudy (anonymous):

nice one, ty

OpenStudy (anonymous):

+c

OpenStudy (dls):

lol yeah

OpenStudy (anonymous):

$$\sin x=\Im\{e^{ix}\}\\\int e^x\sin x\,dx=\Im\int e^xe^{ix}\,dx=\Im\int e^{(1+i)x}\,dx=\dots$$

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