related rate problem

[tandoorichicken]

What is the radius when the area in square units of an expanding circle is increasing twice as fast as the radius?

[Doc Al]

Originally posted by tandoorichicken
What is the radius when the area in square units of an expanding circle is increasing twice as fast as the radius?
Start with the area of a circle (A = πr2) and take the derivative with respect to time. Then apply what's given.