Calculate and interpret average and instantaneous rates from a model
Consider the function for the changing quantity shown below
\[M(u)=40 + 2\,u + \frac{1}{4}\,u^{3}\]
M is measured in grams, and u is measured in minutes
\[u\in[0,3]\]
Evaluate the instantaneous rate for the stated input
\[u=2\]
\[u_1=1,\quad u_2=2\]