13. Find the inverse Laplace: £¹³). L A. 10 (t-3)5 U (t − 3) B. 4t4U (t − 3) (t-3)5 C. D. (t-3)4U (t − 3) E. None 120 14. When using Laplace Transform on the DE: y" + 4y = 1, y(0) = 0, y'(0) = 2, find Y(s). s+1 2s+1 A. Y(s) = B. Y(s) = c. Y(s) = (s²+4) s(s²+4) 2s+1 (s²+4) 1 D. Y(s) = E. None s(s²+4) 15. Find the differential equation that describes the following. A 12 lb weight stretches a spring 2 feet. The weight is released from rest at a point 5 feet above equilibrium. The spring exhibits simple harmonic motion. A. x" 8x0,x(0) = 0, x'(0) = -5 B. x" 8x0,x(0) = 0, x'(0) = 5, x'(0) = 0 C. x" + 16x = 0, x(0) = -5, x'(0) = 0 D. x" 16x0,x(0) = 5, x'(0) = 0 E. None