Solve Differential Equation Using Variation of Parameters

[TrueStar]

Homework Statement

Solve y''+25y=10sec(5t)

Homework Equations

NA

The Attempt at a Solution

I believe I have the correct answer for y_p which is:

2/5log(cos(5t))cos(5t)+2tsin(5t)

When I plug this into the Webwork field, it says it is incorrect. I checked my answer against Wolfram Alpha and they look the same.

I was hoping someone could look at it and identify if it was actually correct or not. If not, I can go through the steps here and try to work it out.

Thanks

 

[TrueStar]

I figured it out. The value within the log should be an absolute value as it came from the integral of the tangent.