Question

Find the Laplace transform of the function f (t) = 4t^3 + t^2 – 6t + 7.

(a) 24/s^4 + 2/s^3 + 6/s^2 + 7/s

(b) 24/s^4 – 2/s^3 – 6/s^2 + 7/s

(c) 24/s^4 + 2/s^3 – 6/s^2 + 7/s

(d) 24/s^4 – 2/s^3 + 6/s^2 + 7/s

The question was asked during a job interview.

The query is from Operational Transforms topic in chapter Intoduction to the Laplace Transform of Network Theory

Answer 1

Correct choice is (c) 24/s^4 + 2/s^3 – 6/s^2 + 7/s

For explanation: L (4t^3 + T^2 -6t +7) = 4L (t^3) + L(t^2)-6L (t) + 7L(1) = 4×3!/s^4 + 2!/s^3 – 6 (1!)/(s^2)+71/s = 24/s^4 + 2/s^3 -6/s^2 + 7/s.