Question

2) If one of the roots of quadratic equation X? - kx - 15 = 0 is -3 then
find the value of 'k'.​

Answer 1

Answer:

( this answer is correct ony if the question mark is clicked in place of ^2 )

k = 2

Step-by-step explanation:

as (-3) is a root of the equation x^2-kx-15 =0, (the symbol '^' represents exponent)

p(x) = x^2 - kx -15   can be written as below by replacing the value of x by (-3)

therefore  p(-3) = (-3)^2 - k(-3) -15

as (-3) is a root of the given equation, it will make the equation's answer =0  

therefore,  

(-3)^2 - k(-3) - 15 = 0

=> 9 + 3k - 15 = 0

=> 9 + 3k = 15

=> 3k = 15 - 9 = 6

=> k = 6/3 = 2

=> k = 2

if you have any doubt you can ask me :)