Answer:
k = 2 or k = -6
Explanation:
10- 7(k + 2)² = -102
10 - 7 (k² + 4 + 4k) + 102 = 0
112 - 7k² - 28 - 28k = 0
-7k² - 28k + 84 = 0
dividing the whole equation by -7
k² + 4k - 12 = 0
k² + 6k - 2k - 12 = 0
k(k + 6) - 2(k + 6) = 0
(k - 2)(k + 6) = 0
thus,
k = 2 or k = -6