In the previous lesson, you learned about co-ordinate system. You know than a point is plotted on Cartesian plane with x-axis and y-axis.

A point has two values – and . For example, is a point.

## Graph of Linear Equations

Therefore, expressions involving two variable can also be plotted using the Cartesian plane known as *Graph of an Equation.*

So, all points that satisfy the equation will give the graph of the equation.

**Example:**

Plot graph of equation for

**Solution:**

Given equation

You can plot the graph using co-ordinate system, but before that find all x and y values that counts as a point.

x-value | y-value | point |
---|---|---|

-1 | 1 | (-1, 1) |

0 | 2 | (0, 2) |

1 | 3 | (1, 3) |

2 | 4 | (2, 4) |

3 | 5 | (3, 5) |

4 | 6 | (4, 6) |

5 | 7 | (5, 7) |

Now, using these points you can plot the graph of the equation.

## Non-Linear Equations

Not all equations are straight line, some equations are non-linear and give a curve for graph.Consider the following example.

**Example 2:**

Plot the graph of equation for .

**Solution 2:**

Given than .

First, you must create a table of values that represent points on the graph.

x-value | y-value | point |
---|---|---|

-2 | 4 | (-2, 4) |

-1 | 1 | (-1, 1) |

0 | 0 | (0, 0) |

1 | 1 | (1, 1) |

2 | 4 | (2, 4) |

You need to plot a graph using these points and each point has x and y values.

**Points to Remember:**

This is something that you can try on your own.

- Linear equation has
*graph of line*. - Quadratic equation is
*graph of parabola*.