Graphing Lines

1. Graphing Lines

2. Graphing Lines • The best way to learn about lines is to work with them without a calculator. • We are going to practice graphing lines by finding our own (x,y) values. • First, we will see how plugging in an “x” value will give you a “y” value.

3. Graphing Lines • Do the points (2,2) and (-3,5) line on the line: y = 3x – 4? • Plug in the “x” value and see if it equals the “y” value. • (2,2) • 2 = 3(2) – 4 • 2 = 6 – 4 • 2 = 2 • Yes, (2,2) lies on the line. • (-3,5) • 5 = 3(-3) – 4 • 5 = -9 – 4 • 5 = -13 • No, (-3,5) is not on the line.

4. Graphing Lines • To graph lines without a calculator, we will use a table. • We will pick the “x” values and plug them into the equation to get the “y” values. • How do we know what “x” values to pick? • I always use my favorites (-2, -1, 0, 1, 2) unless the equation has a fraction. • I will show you as we go!!

5. Graphing Lines • Graph y = 2x - 4 using a table. Plug in the “x” values to find the “y” values. These are your ordered pairs. Graph these points on the graph.

6. Graphing Lines • You can do this with any equation, not just lines. • Create a table and graph y = x2 + 2x + 1.