Find the standard equation of a parabola that has a vertical axis and satisfies the given conditions.

Question

x-intercepts −2 and 8,highest point has y-coordinate 5

Answer 1

y = a(x+2)(x-8)
The vertex is midway between the roots, at x=3, so
y(3) = 5
a(5)(-5) = 5
a = -1/5

y = -1/5 (x+2)(x-8)

See

http://www.wolframalpha.com/input/?i=-1%2F5+%28x%2B2%29%28x-8%29