13 By the factor theorem, if the function is divisible by x - 3 then f(3) = 0. So we have:-
2(3)^3 + k(3)^2 + 7(3) - 3 = 0
9k = 3 - 21 - 54 = -72
k = -72/9 = -8 answer
14. Similarly , f(-4) = 0 , so we have:-
(-4)^3 + 9(-4)^2 + k(-4) - 12 = 0
-64 + 144 - 4k - 12 = 0
4k = -64 + 144 - 12 = 68
k = 68/4
k = 17 answer