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Module 1. Mathematics

If 2x^2 + kx-8 = 0 has two equal real roots, then

  • k is an imaginary number.
  • k=+/-8.
  • k=-8.

Explanation

Equal real roots require the discriminant b^2 - 4ac = 0. Here that is k^2 - 4(2)(-8) = k^2 + 64 = 0, so k^2 = -64. No real value satisfies this, meaning k would have to be imaginary.

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