When you first begin to study a topic or practice a skill, you may not be very good at it, but in time, you will approach the limits of your ability. One model for describing this behavior involves the function

where T is the time required for a particular person to learn the items on a list of L items and a and b are positive constants.

Find the derivative dT/dL and interpret it in terms of the learning model.

T = aLVL b