Graphing a Linear Equation

Graph y = 2x + 1 What we do is pick any value for x that we want and substitute it into the equation. So let x = 1 and substitute.

So y = 2x + 1 becomes y = 2(1) + 1 and hence y = 3 when x = 1. Therefore the first ordered pair is (1,3). Next let us select -1 as the next value for x and substitute it into the equation. Therefore y = 2x + 1 becomes y = 2(-1) + 1 and hence y = -1 when x = -1. Thus the second ordered pair is (-1,-1) So lets select 2 for x and substitute it into the equation. y = 2(2) + 1 Therefore y = 5 and the ordered pair is (2,5). The chart below is used to organize and simplified the procedure we just completed. The selected x value is on the left and the y value obtained after substituting the x value into the equation is on the right.

x | y |

1 | 3 |

-1 | -1 |

2 | 5 |

So lets graph the linear equation y = 2x + 1 using the ordered pairs from the chart (1,3), (-1,-1),(2,5) next