Vertex Form
Vertex Form
Equation from a Graph
Most applications of quadratic functions will require a model to be written. It is possible to write a model when given a graph, table, or a couple of points.
To write an equation from a graph, first locate the vertex and one other point. Substitute the vertex and point into the vertex form and then solve for the a-value.
Example Write the equation of the parabola shown below:
Step 1. Find the vertex and one other point.
The vertex is (3, 1) and another point on the graph is (5, 9).
Step 2. Substitute the vertex and point into the formula and solve for the a-value.
Step 3. Write the equation of the parabola in vertex form.
