Question

If the equation $x^2+2(k+2)x+9=0$ has equal roots, then values of k are -

• A. 1, 4
• B. –1, 5
• C. 1, –5
• D. –1, –4

Answer 1

The correct option is C

1, –5

For, $x^2+2(k+2)x+9k=0$,
value of discriminant
$D=4(k+2{)}^2–4(9)=4(k^2+4k-5)$

If the roots of quadratic equation are real and equal then
$D=0$
$4(k^2+4k-5)=0,k^2+4k-5=0$

$k=-5or1$