Answer
$34$
Work Step by Step
The parabola has a vertical axis.
We write the equation of the parabola as follows:
$(x-h)^2=4p(y-k)$
$6^2=4p(14-16)$
$\implies p=\dfrac{-9}{2}$
and $x^2=4(-9/2) (y-16) \implies x^2=-18(y-16)$
Consider $y=0$
Now, we have: $x^2=-18(0-16) \implies x^2=-18 \times -16$
or, $x=\sqrt {288}$
Now, $2x=2\sqrt {288}=34$
