A sphere has the following volume.

V=4/3r³

Suppose the radius (in feet) of a sphere is a function of timetmeasured in seconds and is given by the following.

r(t) =t²+t+7

FinddV/dt,the derivative of the volume (in units offt³/sec)of the sphere with respect to time.

dV/dt=

How fast is the volume changing (in units offt³/sec)whent=2seconds?

__________ft³/sec