Answer: 36k = k - 6, k = -6/35
Explanation:
The two parts are continuous by themselves. If either weren't, no value of k could fix it.
The only point of discontinuity is x=-6. The function will be continuous for any and all values of k which make k(-6)^2 = -6+k. 36k = k-6, 35k=-6, k=-6/35.