Answer:
The answer to your question is:
16.- x = -6
17.- x = -4; x = 2
18.- x = -5
Explanation:
16.-

x + 6 = 0(x - 4)
x + 6 = 0
x = - 6
17.-

(x + 4) (x - 2) = 0)(x + 6)
(x + 4)(x - 2) = 0
x + 4 = 0 x - 2 = 0
x = - 4 x = 2
18.-

2x + 10 = 0(3x - 12)
2x + 10 = 0
2x = - 10
x = - 10/2
x = -5