The radius of a circle is increasing. At a certain instant, the rate of increase in the area of the circle is numerically equal to twice the rate of increase in its circumference. What is the radius of the circle at that instant?

Question

yuki · Answer

if you let x be your radius, you can find both 
the area and the circumference  as a function of x.

can you do that ?

yuki · Answer

Now you want to know what "rate of increase in the area" and "rate of increase in the circumference" is algebraically.

yuki · Answer

I'm just going to assume that you are reading this.

if you let the Area of the circle "A"
then the rate of increase of A would be A'.
More precisely,  

dA/dt

since we are focusing on how fast the area is changing 
regarding at what time

yuki · Answer

similarly, if you let "C" be the circumference

dC/dt 

would be the rate of increase at a certain time t
where the unit is in meters/second.

yuki · Answer

Do you understand so far ?

dumbcow · Answer

i think they left

yuki · Answer

let me know if you still need help

dumbcow · Answer

oh well here is answer
radiuis = 2

anonymous · Answer

Is there a formula that i need to use to solve this?