Question

The complete set of values of k, for which the quadratic equation $x^2-kx+k+2=0$ has equal roots, consists of

• A. 2 + √2
• B. 2 ± √12
• C. 2 - √12
• D. -2 - √12

Answer 1

The correct option is B

2 ± √12

Equal roots $\Rightarrow △=0$
$k^2-4(k+2)=0$
$k^2-4k-8=0$

$k=\frac{4\overline{+}2\sqrt{12}}{2}$
$=2\overline{+}\sqrt{12}$