Given the differential equation d'y dx² 4. +²y=sec²(cx), cis a constant. Find the constant c if the Wronskian, W = 3. Hence, find the solution of the differential equation. Find the Laplace transform of (a) f(t) = e²t cosh² t (b) f(t) = tsin 6t (c) t³8 (t-1)