Question

The Laplace transform of the function cos(2t) + 7sin(2t) is ____________

(a) \(\frac{s-14}{s^2-4}\)

(b) \(\frac{s+14}{s^2-4}\)

(c) \(\frac{s-14}{s^2+4}\)

(d) \(\frac{s+14}{s^2+4}\)

I had been asked this question in final exam.

This interesting question is from Common Laplace Transforms in chapter Laplace Transform and System Design of Signals and Systems

Answer 1

Correct answer is (d) \(\frac{s+14}{s^2+4}\)

The explanation is: L {cos (2t) + 7 sin (2t)} = \(\frac{s}{s^2+4} + \frac{7 * 2}{s^2+4}\)

= \(\frac{s+14}{s^2+4}\).