Question

If the vertex of the parabola $y=x^2-16x+K$ lies on $x$-axis, then the value of $K$ is

• A. $16$
• B. $8$
• C. $64$
• D. $-64$

Answer 1

Answer: (C)

$y=x^2-16x+K$
$\Rightarrow y={\left(x-8\right)}^2+\left(K-64\right)$
Since vertex lies on $x$-axis
$\Rightarrow y=0$
${\left(x-8\right)}^2+\left(K-64\right)=0$
It can be possible only when $x=8$ and $K=64$.