quadratic equation

Question

You can model an arch at your school using the equation y=−0.9(x+3)(x−3)y=−0.9(x+3)(x−3), where xx and yy are measured in feet. The x-axis represents the ground. Find the width of the arch at ground level.

Answer 1

y = -0.9(x + 3)(x - 3)

x-intercepts at -3 and 3

Width of arch is 9 feet.