Question

If f(x) = (x + 3)(x − 3), complete the square and determine the minimum or maximum value of the function.

Answer 1

Minimum of -9

Explanation:

f(x) = (x + 3)(x − 3)

Distribute:

f(x) = x² − 9

In vertex form:

f(x) = 1 (x − 0)² − 9

The leading coefficient is positive, so this is an upwards parabola, meaning the vertex is a minimum. The vertex is at (0, -9). So the minimum of the function is -9.