The function describes the volume of a right circular cylinder of height 3 ft and radius r feet. find the instantaneous rate of change of the voume with respect to the radius when r = 5

The volume of a right circular cone is calculated through the equation,

                  V = πr²h

where V is volume, r is radius of the base, and h is height. Given that height is 3 ft, this can be simplied into,
 
                V = 3πr²

The rate of change with respect to r is,
                dV/dr = 6πr

Substituting the DALE,

                dV/dr = (6)π(2 m)² = 24π

24π. 

I’m not sure what sujevtbis this