E. Solving Quadratic Equations using Technology

So far you have solved quadratic equations by inspecting graphs, factoring, and using the quadratic formula. Another method is to use technology to graph the corresponding quadratic function and then find the x-intercepts.

Refer to Equipment Room or click here for tutorials on TI-83/84 graphing calculator directions.

Example 1

Graphically solve the equation using technology.

Step 1: Rearrange the equation so one side is equal to zero.

Step 2: Graph the equation of the corresponding function, , using technology.

Step 3: Find the x-intercepts of the graph, which correspond to the roots of the quadratic equation.

Step 4: Verify the roots.

Left side
Right side

16.356675

16.34
LS RS

Left side
Right side

3

3
LS = RS

Please refer to page 401, Example 3, of Principles of Mathematics 11 for another example of using graphing techniques to solve quadratic equations.