Chapter 2.4, Problem 38E

Technology Exercises

Height of Tropical Grass The canopy height (in meters) of the tropical bunch-grass elephant millet $t$ days after mowing (for $t\ge 32$) is

$f(t)=-3.14+.142t-.0016t^2+.0000079t^3-.0000000133t^4$ (Source: Crop Science.)

a. Graph $f(t)$ in the window $[32,250]$ by $[-1.2,4.5]$.

b. How tall was the canopy after $100$ days?

c. When was the canopy $2$ meters high?

d. How fast was the canopy growing after $80$ days?

e. When was the canopy growing at the rate of $.02$ meters per day?

f. Approximately when was the canopy growing slowest?

g. Approximately when was the canopy growing fastest?