The radius of a circular ink blot is increasing at a rate inversely proportional to its area A. Find an expression for dA/dt.
The image is how to work it out, but why do you substitute in the radius? (where r= square root (A/pi) )
differential equation.1 Watch
- Thread Starter
- 10-04-2013 19:14
- 10-04-2013 19:19
Because otherwise the differential won't be solvable as r will be an unknown variable.
You need to do it in order to find dA/dt in terms of A and k