Good morning.

Quick question.

dr/dt=K/r^2

When the radius is 3cm, the radius is increasing at a rate of 5/36pi. Use this fact to find the constant K.

I know that the general form of these growth factors is e^kt but im not sure where the rate and the original radius goes.

Is it e^5/36pi*k=3? doesnt seem right.

2 answers

Hang on ive just realized I need to use the equation for the volume of a sphere first right? v=4/3pir^3 to find a value to plug into my previous equation. Am I on the right track?
yes indeed