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Question
If x − 3 is a factor of x2 − ax − 15, then a =
Options
-2
5
-5
3
Solution
As (x -3) is a factor of polynomial f(x) = x2 − ax − 15.
i.e. f(3) = 0
Therefore,
`(3)^2 - a(3) -15 = 0`
`9-3a - 15 = 0`
`a = -2`
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