(1) In # 2,is the question asking for the total work or the work done at a particular moment in time??
(2) In Chpt. 8, #40, question B, the limits with respect to what? I really don't understand this one...
(1) Prob.2 is asking about the total work done during some finite duration in time.
(2) Part B is asking: Given the specified intial conditions and the potential shown in figure 42, what is the largest and smallest value of x that the particle will EVER have. Use conservation of energy to solve this one: at the extreme points of motion (called 'turning points') the instantaneous velocity is zero, so the PE equals the total energy.