Question

If x=3 is one root of the quadratic equation x2-2kx-6=0 , find the value of k.

Answer 1

We have,

=> x² - 2kx - 6 = 0

Substituting x = 3 in this equation :-

=> (3)² - 2k(3) - 6 = 0
=> 9 - 6k - 6 = 0
=> -6k + 3 = 0
=> -2k + 1 = 0
=> k = ½

Hope this helps.....

Answer 2

Let p(x) = x^2 – 2kx – 6 = 0

x = 3 is one root of the quadratic equation

Remainder = p(3) = 0

p(3) = 0

(3)^2 – 2k(3) – 6 = 0

– 6k = - 3

k =  6/3

k = 1/2