Find the value of k for which the equation kx[x-2]+6=0 has equal roots.
@Himanshu4: Good answer! Keep posting!
The given equation is kx (x – 2) + 6 = 0.
kx (x – 2) + 6 = 0
∴ kx2 – 2kx + 6 = 0
Here a = k, b = – 2k and c = 6.
Discriminant of the quadratic equation = D = b2 – 4ac = (–2k)2 – 4 × k × 6 = 4k2 – 24k
Roots of the given quadratic equation are equal.
∴ D = 0
⇒ 4k2 – 24k = 0
⇒ 4k(k – 6) = 0
⇒ k = 0 or k – 6 = 0
⇒ k = 0 or k = 6
∴k = 6 (∵ k ≠ 0)
Thus, the value of k is 6.