arch is shape like a arch can be parabola the arch can be appriximated by y =630-0.00635x2 both x and y distance in ft origin is the point on the ground below the arch apex find the x intercepts and how wide is the arch base

Question

arch is shape like a  arch can be parabola the arch can be appriximated by y =630-0.00635x2 both x and y distance in ft origin is the point on the ground below the arch apex find the x intercepts and how wide is the arch base

anonymous · Answer

Well, to find the x intercepts, we need to find x when y=0.
$$0=630-.00635x^2$$
Solving for x you should get, 
$$x^2=630\div.00635$$
Because the arch is a parabola, we can use symmetry to find the length of the base.
Remember when taking the square root of a number to include +/-.
$$x=+/-\sqrt{99212.6}$$
Bacause of symmetry, the distance is simply 2 times x, which should be 629.961 feet.