1(ii)
If x - 2 is a factor of x3 - kx - 12, then the value of k is :
- (a)3
- (b)2
- (c)-2
- (d)-3
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By factor theorem,
If x - a is a factor of f(x), then f(a) = 0.
Given,
x - 2 is a factor of x3 - kx - 12
⇒ x - 2 = 0
⇒ x = 2.
∴ 23 - 2k - 12 = 0
⇒ 8 - 2k - 12 = 0
⇒ -2k - 4 = 0
⇒ 2k = -4
⇒ k = $-\frac{4}{2}$ = -2.
Hence, Option 3 is the correct option.