`int(xe^(2x))/(1+2x)^2dx`
If f(x) and g(x) are differentiable functions, then
`intf(x)g'(x)=f(x)g(x)-intf'(x)g(x)dx`
If we rewrite f(x)=u and
g'(x)=v, then
`intuvdx=uintvdx-int(u'intvdx)dx`
Using the
above method of integration by parts,
Let `u=xe^(2x)`
`u'=xd/dx(e^(2x))+e^(2x)d/dx(x)`
`u'=x(2e^(2x))+e^(2x)`
`u'=e^(2x)(2x+1)`
`v=1/(1+2x)^2`
`intvdx=int(1/(1+2x)^2)dx`
Let's integrate by the use of
substitution method,
Let t=1+2x
`dt=2dx`
`int(1/(1+2x)^2)dx=intdt/(2t^2)`
`=1/2(t^(-2+1)/(-2+1))`
`=-1/(2t)`
substitute back t=1+2x,
`=-1/(2(1+2x))`
`int(xe^(2x))/(1+2x)^2dx=xe^(2x)int(1/(1+2x)^2)dx-int(d/dx(xe^(2x))int(1/(1+2x)^2)dx)dx)`
`=xe^(2x)(-1/(2(1+2x)))-inte^(2x)(1+2x)(-1/(2(1+2x)))dx`
`=(-xe^(2x))/(2(1+2x))+inte^(2x)/2dx`
`=(-xe^(2x))/(2(1+2x))+(1/2)e^(2x)/2`
`=e^(2x)/4-(xe^(2x))/(2(1+2x))`
Add a constant C to the
solution,
`int(xe^(2x))/(1+2x)^2dx=e^(2x)/4-(xe^(2x))/(2(1+2x))+C`
No comments:
Post a Comment