Which equations represent a function whose graph opens downward?

450 feet at ground level

Step-by-step explanation:

The width of the bridge at ground level will be where the function intercepts the x-axis also known as the roots or zeros of the function. They are found using the zero product property to set each factor equal to 0.

This means (x-225) = 0 and (x + 225) = 0. So x = -225, 225.

This means the width is the absolute value of |-225| + 225 since distance cannot be negative. This makes it 450 feet.