Question

If one of the roots of quadratic equation x2 – kx – 15 = 0 is -3 then

find the value of ‘k’.​

Answer 1

Answer:

The value of k is 2.

Step-by-step explanation:

x² - Kx - 15 = 0

and one root is -3

and we also know that AB = c/a ( let A and B are the roots of equation)

so AB = c/d

-3B = -15/1

3B = 15

B = 5

So the second root is 5.

Now we know that A+B = - b/a

So 5+(-3) = -(-k)/1

2 = k

And that's the answer k = 2

Answer 2

Answer:

k=2

Step-by-step explanation:

x =-3

x²- kx - 15 = 0

( -3 )² k( -3 ) - 15 = 0

9 + 3 k -15 =0

3 k = 15 -9

3 k = 6

k = 6 / 3

k=2