Integral of exp(2x)*cos(x/2) dx
The solution
Detail solution
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Use integration by parts, noting that the integrand eventually repeats itself.
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For the integrand e2xcos(2x):
Let u(x)=cos(2x) and let dv(x)=e2x.
Then ∫e2xcos(2x)dx=2e2xcos(2x)−∫(−4e2xsin(2x))dx.
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For the integrand −4e2xsin(2x):
Let u(x)=−4sin(2x) and let dv(x)=e2x.
Then ∫e2xcos(2x)dx=8e2xsin(2x)+2e2xcos(2x)+∫(−16e2xcos(2x))dx.
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Notice that the integrand has repeated itself, so move it to one side:
1617∫e2xcos(2x)dx=8e2xsin(2x)+2e2xcos(2x)
Therefore,
∫e2xcos(2x)dx=172e2xsin(2x)+178e2xcos(2x)
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Now simplify:
172(sin(2x)+4cos(2x))e2x
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Add the constant of integration:
172(sin(2x)+4cos(2x))e2x+constant
The answer is:
172(sin(2x)+4cos(2x))e2x+constant
The answer (Indefinite)
[src]
/ 2*x /x\ /x\ 2*x
| 2*e *sin|-| 8*cos|-|*e
| 2*x /x\ \2/ \2/
| e *cos|-| dx = C + ------------- + -------------
| \2/ 17 17
|
/
∫e2xcos(2x)dx=C+172e2xsin(2x)+178e2xcos(2x)
The graph
2 2
8 2*e *sin(1/2) 8*cos(1/2)*e
- -- + ------------- + -------------
17 17 17
−178+172e2sin(21)+178e2cos(21)
=
2 2
8 2*e *sin(1/2) 8*cos(1/2)*e
- -- + ------------- + -------------
17 17 17
−178+172e2sin(21)+178e2cos(21)
-8/17 + 2*exp(2)*sin(1/2)/17 + 8*cos(1/2)*exp(2)/17
Use the examples entering the upper and lower limits of integration.