What is the axis of symmetry of the graph of #y=7(x+1)(x-3)#?
Note that this is a parabola in standard position (vertical axis of symmetry).
The axis of symmetry passes through the vertex.
One method of determining the vertex is by noting that the derivative of the function is equal to zero at the vertex
(we could now calculate the value of
The axis of symmetry is
An other way:
In a parabola of this kind you can also find the midpoint between the two points where the curve crosses the
As you will see
Same answer, less work, but this method is not always usable.