Solving a Linear Equation

This particular example is fairly simple to do algebraically.  We will look at several ways to work this problem with the calculator.  Which method is best will vary depending on the particular problem.

Method #1 - Graphical

This method will first involve a little algebraic manipulation.  Move all terms to one side of the equation.  We end up with 4x - 12 = 0.

In the <GRAPH> "Y=" window, enter 4x - 12 in for Y₁.

Graph the function by choosing "GRAPH", making sure to adjust the window, if necessary, so we can see where the graph crosses the x-axis.

Press <MORE> to see more menu options.  Press <F1> to choose "MATH."

We are interested in when the function equals 0 so press <F1> to choose "root."  (It is <F3> on the TI-85.  Also, the TI-85 does not ask for left and right bounds so TI-85 users should ignore the next couple steps.)

The calculator is asking for a left bound.  That is, it is wanting us to use the arrow keys to move the cursor (currently located at the point listed at the bottom of the screen) to a point on the graph whose x-coordinate is to the left of the x-coordinate of the x-intercept.  In this particular case, the cursor is already to the left of the x-intercept but we will move it a bit so it will show in the picture.