Graphing Linear EquationsDate: 04/11/2003 at 17:40:47 From: Aimee Subject: Graphing linear equations and Inequalities I was recently on math.com and I am a little confused. They asked me to find the slope and the y-intercept. But how do I find the points on the line so that I can get the answers? There aren't any dots on the lines to find the coordinates. Please help. Date: 04/14/2003 at 00:15:07 From: Doctor Ian Subject: Re: Graphing linear equations and Inequalities Hi Aimee, You can choose _any_ points on the line to find the slope and intercept. For example, pick any value of x, and mark it on the x-axis. +---|---*---|---|---| 1 2 3 4 5 Then move straight up (or down) until you hit the line. | / 6 - / | / 5 - . | /. 4 - / . | / . 3 - / . | / . 2 - / . |/ . 1 / . | . +---|---*---|---|---| 1 2 3 4 5 Then move straight over until you hit the y-axis. | / 6 - / | / 5 *........ | /. 4 - / . | / . 3 - / . | / . 2 - / . |/ . 1 / . | . +---|---*---|---|---| 1 2 3 4 5 Those x and y values are the coordinates of one point on the line. In this case, x=2, y=5 --> (2,5) is one point on the line. Do the same thing again to find a second point, | / 6 - / | / 5 *........ | /. 4 - / . | / . 3 *.... . | /. . 2 - / . . |/ . . 1 / . . | . . +---*---*---|---|---| 1 2 3 4 5 and you can use those two points to find the slope. Note that you may need to do a little exploring to find x values that give you nice, round y values. That isn't strictly necessary, but it can make your calculations easier. Does this help? - Doctor Ian, The Math Forum http://mathforum.org/dr.math/ |
Search the Dr. Math Library: |
[Privacy Policy] [Terms of Use]
Ask Dr. Math^{TM}
© 1994- The Math Forum at NCTM. All rights reserved.
http://mathforum.org/dr.math/