- #1

Destroxia

- 204

- 7

## Homework Statement

y'' + y =3*sin(2t) +t*cos(2t)

Okay, so I have found the complimentary solution, and the first partial solution as listed in my work below.

My problem is the work on the second partial solution. I have got all the derivatives plugged into the differential equation, my problem is solving for the coefficients. I've tried setting the coefficients paired with a t and cos equal to 1, and all the rest equal to 0, yet this returns a false result. I have tried almost 20 different combinations of different coefficients equal to different things and they all return false, but I am fairly certain the differentiating was done correctly... Or was perhaps my guess of (At+B)(C*cos(2t)+D*sin(2t)) incorrect for this solution? I don't understand what I am doing wrong.

Main Issue: Solving for the undetermined Coefficients at the end