Use the method of variation of parameters to find a particular solution to the following differential equation eox y" - 16y' + 64y = 4+ x2 Enter your answer as a symbolic function of x, as in these Do not include 'y = ' in your answer. examplesl A 180 lb weight stretches a spring 18 feet. The weight hangs vertically from the spring and a damping force numerically equal to 15 times the instantaneous velocity acts on the system. The weight is released from 9 feet above the equilibrium position with a downward velocity of 39 ft/s. (a) Determine the time (in seconds) at which the mass passes through the equilibrium position. (b) Find the time (in seconds) at which the mass attains its extreme displacement from the equilibrium position. :| Round your answer to 4 decimals. |:| Round your answer to 4 decimals