Question

One root of the quadratic eqn 2x^2 - 8x - k =0 is 5/2. find the other root and value of k

Answer 1

let the other root be y
si y+5/2= 4
=>y = 3/2
and , 3/2*5/2=k/2
=> k = 15/2

Answer 2

When we put value of x as 5/2 then it will give 0 as resultant.

2x² - 8x - k = 0

$2 \times ( { \frac{5}{2}) }^{2} - 8 \times \frac{5}{2} - k = 0$

$\frac{25}{2} - 20 - k = 0$


$\frac{25 - 40 - 2k}{2} = 0$

- 15 - 2k = 0

k = - 15 / 2