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If x + 1 is a factor of x3 + 3×2 + kx + 4,…

If x + 1 is a factor of x3 + 3x2 + kx + 4, find the value of k
  • A.
    6
  • B.
    -6
  • C.
    8
  • D.
    -8
Correct Answer: Option A
Explanation

x + 1 is a factor of x3 + 3x2 + kx + 4
Let f(x) = x3 + 3x2 + kx + 4
∴ f(-1) = (-1)3 + 3(-1)2 + k(-1) + 4 = 0
-1 + 3 – k + 4 = 0
∴ k = 6

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