Question: What is the rate of change of the volume of the prism at that instant (in cubic meters per second) ?
A function can be dependent on one or more variables. The change in the function due to a change in one o its variables is given by the functions derivative with respect to that variable. For functions that are composed of products of its variables, we may use the product rule to determine its derivative.
The volume of a square prism with base a and height h is given by
