Correct Answer - Option 2 : ± 4
Concept:
Let us consider the standard form of a quadratic equation, ax2 + bx + c = 0
Discriminant = D = b2 – 4ac
- If the Discriminant > 0 then the roots are real and distinct.
- If the Discriminant = 0 then the roots are real and equal.
- If the Discriminant < 0 then the roots are Imaginary.
Calculation:
Given:
The roots of the quadratic equation x2 - kx + 4 = 0 are equal.
For equal roots, Discriminant = 0
⇒ D = b2 – 4ac = 0
⇒ (-k)2 - 4 × 1 × 4 = 0
⇒ k2 - 16 = 0
⇒ k2 = 16
∴ k = ± 4