The given equation is :
[tex]y=x^{2} -4x-9[/tex]
Replacing y as zero, we get,
[tex]x^{2} -4x-9=0[/tex]
Now solving this quadratic equation using formula:
[tex]x1,2=\frac{-b+\sqrt{b^{2}-4ac}}{2a}[/tex] and
[tex]x1,2=\frac{-b-\sqrt{b^{2}-4ac}}{2a}[/tex]
Putting a=1, b=-4, c=-9 we get
[tex]x=2+\sqrt{13}[/tex] and [tex]x=2-\sqrt{13}[/tex]
So, option B is the correct answer.
