The above-ground volume (stem and leaves) of a plant is Va(t) = 3.0t + 20.0 + t2/2, and the below-ground volume (roots) is Vb(t) = -1.0t + 40.0 where t is measured in days and volumes are measured in cm3. The total volume is V(t) = Va(t) + Vb(t).
Each of the above measurements is the sum of two components. Find the formula for the sum. Sketch a graph of each component and the total as functions of time for 0 ≤ t ≤ 3. Describe each component and the sum in words.