Thread: Sign Graphs

Can someone explain how to do sign graphs for inequalities?

Like (x-3)(x+4)>0

Hello, mm99!

Can someone explain how to do sign graphs for inequalities?

Like: .

Here's one way . . .

We have the graph of: .

This is an up-opening parabola.
We want to know when this graph is positive (above the x-axis).

Draw a sketch (or visualize it) . . .
The x-intercepts are
The graph is positive to the left and right of the intercepts.

Code:

                      |
     *                |            *
                      |
      *               |           *
       *              |          *
    - - * - - - - - - + - - - - * - -
       -4 *           |       * 3
              *       |   *
                    * |
                      |

Therefore: .