Question

Let f(x)=x² - 6x - 27.

Enter the x-intercepts of the quadratic function in the boxes.
X =
and x =

Answer 1

x = 9 or -3

Explanation:

As this is a quadratic function

`x^(2) -6x-27=0\\`

to solve find the two values that add to make -6 and multiply to make -27:

-9 + 3 = -6

-9 × 3 = -27

so the equation can be factorised as

(x - 9)(x + 3) = 0

to solve for x, make each bracket = 0 and rearrange

x - 9 = 0

x = 9

OR

x + 3 = 0

x = -3

therefore x = 9 or -3