If x – 4 is a factor of x2 – x – k, then k is
- 4
-
12
- 20
- 2
The correct answer is: B
Explanation
Let f(x) = x2 - x - kThen by the factor theorem,
(x - 4): f(4) = (4)2 - (4) - k = 0
16 - 4 - k = 0
12 - k = 0
k = 12
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