## Sketching a Quadratic Graph

To sketch a graph we need to find a set of points. This is most easily done by drawing up a table. The table for the graph given by the equation

-3 | -2 | -1 | 0 | 1 | 2 | 3 | |

9 | 4 | 1 | 0 | 1 | 4 | 9 | |

3 | 2 | 1 | 0 | -1 | -2 | -3 | |

1 | 1 | 1 | 1 | 1 | 1 | 1 | |

13 | 7 | 3 | 1 | 1 | 3 | 7 |

When filling in the table the most important thing to remember is that when you square a minus number you obtain a positive number, egnot -9.

DO NOT RELY ON YOUR CALCULATOR TO WORK OUT THE SQUARE OF A MINUS NUMBER.

Your calculator will tell you thatwhich is exactly wrong:is correct. The graph is shown below.