factoring by completing the square: 3k^2+18k+15=0
3k^2 + 18k + 15 = 03k^2 + 18k = -15k^2 + 6k = - 5k^2 + 6k + 9 = -5 + 9(k + 3)^2 = 4k + 3 = (+-) sqrt 4k = -3 (+-) sqrt 4k = -3 + 2 = -1k = -3 - 2 = -5so k = -1 and -5