Write the value of k for which the quadratic equation x2 – kx + 4 = 0 has equal roots.
Quadratic equation has equal roots then d = b2 – 4ac = 0
Here a = 1, b = k and c = 4
So b2 – 4ac = 0
⇒ k2 – 4 × 1 × 4 = 0
⇒ k2 – 16 = 0
⇒ k = 
4
1
Write the value of k for which the quadratic equation x2 – kx + 4 = 0 has equal roots.
Quadratic equation has equal roots then d = b2 – 4ac = 0
Here a = 1, b = k and c = 4
So b2 – 4ac = 0
⇒ k2 – 4 × 1 × 4 = 0
⇒ k2 – 16 = 0
⇒ k = 4