Question

The discriminant of $2x^2-kx-9=0$ is 108 . Find the number of values exist for $k$.

• A. 0
• B. 1
• C. 2
• D. More than 2

Answer 1

Answer: (C)

Given: $2x^2-kx-9=0$
Discriminant $(\Delta )=b^2-4ac$
$\Rightarrow (-k{)}^2+4(2)(9)=108$
$\Rightarrow k^2+72=108$
$\Rightarrow k^2=36,k=\pm 6$