Determine the longest interval in which the given initial value problem is certain to have a unique twice-differentiable solution. Do not attempt to find the solution. (Enter your answer using interval notation.) ty'' + 8y = t, y(1) = 1, y'(1) = 8

The motion of a weight that hangs from a spring is represented by the equation h=8sin(2pi/3t). it models the weight’s height above or below the rest position as a function of time. approximately when will the object be 3 inches above the rest position?