Question

One of the roots of quadratic equation 2x2 + kx - 2 = 0 is -2, find k.​

Answer 1

2x

2

+kx−2=0

if one root os -2 then

if satisfy the equation

2(−2)

2

+k(−2)−2=0

8−2−2k=0

k=

2

6

=3

Answer 2

Answer:

$k = 3$

Step-by-step explanation:

$since \: x = - 2 \: is \: a \: root \: of \: the \: equation \: 2{x}^{2} + kx - 2 = 0\\ so \: 2{ (- 2)}^{2} + k( - 2)- 2 = 0 \\ 2 \times 4 - 2k - 2 = 0 \\ 8 - 2k - 2 = 0 \\ - 2k = 2 - 8 \\ - 2k = - 6 \\ k = \frac{ - 6}{ - 2} \\ k = 3$