The function h represents the height of the bridge, in feet, and x represents the distance along the base of the model from the leftmost edge, in feet.

H(x)=-0.5(x-4)^2+2

h(x)=0→-0.5(x-4)^2+2=0
Solving for x:
-0.5(x-4)^2+2-2=0-2
-0.5(x-4)^2=-2
-0.5(x-4)^2/(-0.5)=-2/(-0.5)
(x-4)^2=4
sqrt [(x-4)^2]=+-sqrt(4)
x-4=+-2
x-4+4=+-2+4
x=4+-2
x1=4-2→x1=2
x2=4+2→x2=6

Second option. The brigde touches the base of the model at 2 feet and 6 feet from the leftmost edge of the model