Factored Form

Writing Equations

Since the factored form shows the x -intercepts of the function, it is possible to write an equation in factored form if you know the x -intercepts. Substitute values into the form: WritingEquation1 and simplify.
Example Model the quadratic function graphed below using an equation in factored form.


WritingEx1-1



Step 1. Find the x-intercepts.

The x-intercepts of the graph are (0, 0) and (4, 0).

Step 2. Substitute the x-intercepts into the general form.

WritingEx1-2

Step 3. Substitute another point from the graph into the general form and solve for the a-value.

WritingEx1-3

Step 4. Substitute the a-value into the formula.

WritingEx1-4