Question

How do you graph and label the vertex and axis of symmetry of `y=(x+2)(x-4)`?

Answer 1

To find the x intercepts:
When x=4, y=0 and when x=-2, y=0

To find the y intercept:
When x=0, y=-8

To find the x coordinate of the axis of symmetry:
Expand the brackets `=> y=x^2-2x-8`

`(-b)/(2a) => (- -2)/(2xx1)=2/2=1`

To find the coordinates of the vertex
When x=1, y=-9

Minimum at (1, -9)
Axis of symmetry is x=1
y intercept (0, -8)
x intercepts (4,0) and (-2,0)