Answer:
k = 3
Step-by-step explanation:
By the Remainder theorem if f(x) is divided by (x + h) , then the remainder is f(- h), thus
f(- 3) = (- 3)³ + 2k(- 3)² + 3(- 3) - 6 = 12 , then
- 27 + 18k - 9 - 6 = 12
18k - 42 = 12 ( add 42 to both sides )
18k = 54 ( divide both sides by 18 )
k = 3
