Question

If x = 3 is one root of the quadratic equation x² – 2kx – 6 = 0, then value of k is :

(a) 1
(b) 1/2
(c) 1/3
(d) 3

Answer 1

Correct option is (b) 1/2

x = 3 is one root of the quadratic equation x² - 2kx - 6 = 0.

So, x = 3 must satisfy the given quadratic equation.

\(\therefore 3^2 - 2k \times 3 - 6 = 0\)

⇒ \(6k = 9 - 6 = 3\)

⇒ \(k = \frac 36 = \frac 12\)

Answer 2

If x = 3 is one root of the quadratic equation x2 – 2kx – 6 = 0, then value of k is: (b) 1/2