The graph of the equation y=ax^2+bx+c has the line x=4 as an axis of symmetry. Find b/a .
If x = 4 is the axis of symmetry....then the x coordinate of the vertex = 4
And the x coordinate of the vertex = -b/a
So
4 = -b/a
-4 = b/a
It means that - b/2a = 4 multiply both sides by -2
b/a = -8