Question

if x equal to 3 is one of the root of quadratic equation x square - 2k x minus 6 is equal to zero then find the value of k

Answer 1

$since \: x = 3 \: is \: a \: root \: \: it \: satisfies \\ the \: quadratic \: equation$
$thus \: {3}^{2} - 2k \times 3 - 6 = 0 \\ 3 - 6k = 0 \\ k = \frac{1}{2}$

Answer 2

let put the value of x be 3 as given...
after putting the value of x in the equation
3'2-2k(3)-6
9-6k-6
3-6k
3-6k=0
k=1/2

thats the ans hope it helped