One root of x^2 + kx - 8 = 0 is square of the other. Then the value of k is

One root of x2 + kx - 8 = 0 is square of the other. Then the value of k is

  1. 2
  2. -2
  3. 8
  4. -8

Answer

Let the roots of the quadratic equation be α and α2.

Product of roots = α*α2 = -8

α3 = -8

α = -2

Roots are -2 and 4

42 + 4k - 8 = 0

k = -2

The correct option is B.