If x - 4 is a factor of x2 - x - k, then k is
A
4
B
12
C
20
D
2
Verified Correct Answer: B.
Step-by-Step Mathematical Solution
Let f(x) = x2 - x - k
Then by the factor theorem,
(x - 4): f(4) = (4)2 - (4) - k = 0
16 - 4 - k = 0
12 - k = 0
k = 12
Source: Myschool Past Questions Archive (Record #27047)