William, a logistician, needs to route a freight train that is 20 feet at its tallest point and 10 feet at its widest point within 3 days. The most direct path includes a single-track tunnel that needs 24 hour notice prior to use. If the tunnel is roughly modeled by f(x)=-0.1x^2+3.2x-3.5, should William make arrangements for the train to use the tunnel? Show work the supports your conclusion.
Find the zeroes of the equation....the distance between them will give you the width
Find the Vertex to know the height....
vertex is given by - b / 2a = - 3.2 / (2*(-.1) ) = 3.2/.2 = 16 feet (equation parameters were not supplied...hence the ?)
at x = 16 f(x) = -.1(16^2) + 3.2(16) - 3.5 = 22.1 feet (?) tall
Now we know it is 22.1 feet tall at x = 16 but we still do not know the width....
Find the zeroes using quadratic equation
-3.2 +- ( sqrt(3.2^2 - 4(-.1)(-3.5) / 2(-.1) = 30 .86 - 1.134 = 29.76 feet wide at the BASE
The train looks like it will fit....... this equation is a parabola BUT.....at y = 20 is the equation > 10 for the train to fit???
20 = -.1x^2 + 3.2 x - 3.5 ??? Yields x = 11.417 and 20 .583 which is less than 10 (9.166)
The train may not fit !