I have a practice question that I am stuck on and need help.
A certain insect pest has infested a cornfield. The pests are spreading through the field in a circular pattern at the rate of 3m/day. When the radius of the infested area is 70m. How fast is the area of the infested region increasing at that moment?
The answer is 420(pi)m^2 /day
I know it has to do with derivatives and rates of change, but I'm having trouble finding the connection for this one.
area-PI r^2
d area/dtime= 2PI r dr/dt
plug the numbers, and solve.
is that area - pir^2?
as in negative?
we use the ^ to say exponent.