How do you integrate int e^xsin4xdx using integration by parts?

1 Answer
Nov 3, 2015

inte^xsin(4x)dx=frac{e^xsin(4x)-4e^xcos(4x)}{17}+c,
where c is the integration constant.

Explanation:

inte^xsin(4x)dx=-1/4inte^xfrac{d}{dx}(cos(4x))dx

=-1/4[e^xcos(4x)-intfrac{d}{dx}(e^x)cos(4x)dx]

=1/4inte^xcos(4x)dx-1/4e^xcos(4x)

=1/16inte^xfrac{d}{dx}(sin(4x))dx-1/4e^xcos(4x)

=1/16[e^xsin(4x)-intfrac{d}{dx}(e^x)sin(4x)dx]-1/4e^xcos(4x)

=1/16e^xsin(4x)-frac{1}{16}inte^xsin(4x)dx-1/4e^xcos(4x)

frac{17}{16}inte^xsin(4x)dx=1/16e^xsin(4x)-1/4e^xcos(4x)+c_1,
where c_1 is the constant of integration.

inte^xsin(4x)dx=frac{e^xsin(4x)-4e^xcos(4x)}{17}+c_2,
where c_2=frac{16c_1}{17}.