Yes, and using the fact that is the real part of (that is the "complex exponential") makes it very easy.
Using the complex exponential, find the most general function f such that
f''(x) = e-3tcos (2t) , for t element of reals.
f''(x) is second derivative.
Do i tackle this problem by taking the anti derivative of both sides, then doing it one more time to get
f(x) = ............
I still dont really get it is there any other way to help explain it? i did the first derivative and got down to
1/13*e^(-3t) *( -3 cos2t + sin2t) + c
What would be the next step or have i gone about it the hard way? thanks for your help.