Free points. please do not comment or start a conversation below tho. thanks

Trish receives $450 on the first of each month. josh receives $450 on the last day of each month. both trish and josh will receive payments for next four years. at a discount rate of 9.5 percent, what is the difference in the present value of these two sets of payments?

What could explain what happened when the time was equal to 120 minutes

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?