Question

What is the axis of symmetry of the function f(x)= -(x+9)(x-21)

Answer 1

The axis of symmetry is x = 6

Explanation:

To find this, first find the two x-intercept values and then take the average. This will always be the line of symmetry.

x + 9 = 0

x = -9

x - 21 = 0

x = 21

Now take the average of these two numbers.

(-9 + 21)/2

12/2

6