Answer:
k = -6/35
Step-by-step explanation:
To make the function continuous
kx^2 = x+k
These must be equal where the function is defined for two different intervals
This is at the point x=-6 so let x=-6
k(-6)^2 = -6+k
36k = -6+k
Subtract k from each side
36k-k = -6+k-k
35k = -6
Divide by 35
35k/35 = -6/35
k = -6/35
The area of a circle is given by

We can solve this equation for r: divide both sides by pi:

Consider the (positive) square root of both sides:

So, in your case, we have
