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

Jul 29, 2018

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 $\implies y = {x}^{2} - 2 x - 8$

$\frac{- b}{2 a} \implies \frac{- - 2}{2 \times 1} = \frac{2}{2} = 1$

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)