**Plotting Points Method**

- Find ordered pair solutions
- Choose values for one variable
- Find the value for the other variable

- Plot the ordered pair solutions
- Draw the line or curve that connects the ordered pairs

Example: Graph by the plotting points method.

** 1. Find ordered pair solutions. We can organize this information in a table.**

**Choose values for one variable**

When the equation is written in “y=” format it is easier to choose values for x and then find the y’s. Although you are allowed to choose any x values, for this table I have used a standard set of x’s so that we have a variety. Some negatives, some positives and zeros.

x | y |
---|---|

-2 | |

-1 | |

0 | |

1 | |

2 |

**Find the values for the other variable**

To find the y’s substitute the value of x into the equation and simplify to find y.

x | y |
---|---|

-2 | (-2)^2-5=4-5=-1 |

-1 | (-1)^2-5=1-5=-4 |

0 | (0)^2-5=0-5=-5 |

1 | (1)^2-5=1-5=-4 |

2 | (2)^2-5=4-5=-1 |

**2. Plot the ordered pair solutions**

Using the table above we have 5 ordered pairs

Plot the ordered pairs using the rectangular coordinate system.

**3. Draw the line or curve that connects the ordered pairs.**

When you look at the plotted ordered pairs you should see a pattern the that points make. In this case, the points form a “u” shaped curve called a parabola. Most of the equations with x squared have graphs of this shape.

The line represents all of the ordered pairs that are solutions to the equation .

Here is a youtube video with a similar example.