Question

The stream of water from a fountain follows a parabolic path. The stream reaches a maximum height of 12 feet, represented by a vertex of (8,12)​ , and lands 16 feet from the water jet, represented by (16,0)​ . Write a function in vertex form that models the path of the stream

Answer 1

y = (-5.33)(x - 8)^2 + 12

Explanation:

The graph is a parabola which opens down and has its vertex at (8, 12). We can immediately write y = a(x - 8)^2 + 12, knowing that if x = 8, y = 12. To find the coefficient '1', substitute 16 for x and 0 for y:

0 = a(16 - 8)^2 + 12, or

-64a = 12, or a = -64/12 = 5.33

Then the desired function is:

y = (-5.33)(x - 8)^2 + 12

Answer 2

y=-3/16(x-8)^2+12

Explanation:

Refer to the vertex form equation for a parabola:

y=a(x-h)^2+k where (h,k) is the vertex.

Therefore, we have y=a(x-8)^2+12 as our equation so far. If we plug in (16,0) we can find a:

0=a(16-8)^2+12

0=64a+12

-12=64a

-12/64=a

-3/16=a

Therefore, your final equation is y=-3/16(x-8)^2+12