Answer:
y = -x^2 + 11x - 24
Explanation:
Comment
The two roots of the equation are the represented by the points on the x axis. Those two points are
So far what your have is
y = a(x - 3)(x-8)
Usually, a has a value of one. You cannot take that for granted. So we'll use point (4,4) to see if a is anything other than 1
4 = a(4 - 3)(4 - 8)
4 = a(1)(-4
a = - 1
Note: This a perfectly reasonable answer. The graph is upside down and that means that the number in front of x^2 must be minus.
y = -1(x - 3)(x - 8)
y = -1(x^2 - 11x + 24)
y = -x^2 + 11x - 24