Question

Find the Laplace of f(t) = tcos3t.

Answer 1

\[L(tcos3t) = \int\limits_{0}^{\infty}e ^{-st}.(tcos3t)dt\]
from here there is only integral work to go. For more detail, I suggest you to read this http://tutorial.math.lamar.edu/Classes/DE/LaplaceTransforms.aspx#Laplace_Trans_Ex2a

Btw, your assignment is looks like almost the same that i have been working on