Question

The roots of x² + kx + k = 0 are real and equal, find k.

Options

• 0

• 4

• 0 or 4

• 2

Answer 1

0 or 4

Explanation:

Given quadratic equation is x² + kx + k = 0 

For real and equal roots, D = 0 

b² - 4ac = 0

⇒ k² - 4 × 1 × k = 0

⇒ k² - 4k = 0

⇒ k (k - 4) = 0

⇒ k = 0 or k - 4 = 0

⇒ k = 0 or k = 4  

Hence, the correct answer is 0 or 4.