@jimmysmith560's answer is correct and the question is badly written. For a start, a satellite dish is a three-dimensional object, and further it is finite, so saying it has an equation like the one given is problematic. The question should be re-written as something like:
A satellite dish is in the shape of a parabola rotated about its axis. With all distances in metres, a cross-section
of the dish through its vertex matches that part of
that is on or above the
y-axis.
Find
w, the width of the dish at its widest point, in exact form and to 1 decimal place.
The answer would be