SOLUTION: I'm trying to help my stepson with his math. It is graphing. The question is y= -2x+7. I'm not sure how to graph this. Could you show me the steps to solving this problem ? Thank y

Algebra ->  Graphs -> SOLUTION: I'm trying to help my stepson with his math. It is graphing. The question is y= -2x+7. I'm not sure how to graph this. Could you show me the steps to solving this problem ? Thank y      Log On


   

Question 802495: I'm trying to help my stepson with his math. It is graphing. The question is y= -2x+7. I'm not sure how to graph this. Could you show me the steps to solving this problem ? Thank you
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
Linear equations, such as y=+-2x%2B7 graph as straight lines.
To graph the line, you just need to determine two points and connect them with a straight line.
However, some teachers may insist on having more points.
They may like their work shown in a certain way, maybe with a table of x and y values.
Your stepson may know if the teacher has some special requirements.
It is a good idea to use grid paper, or graph paper.
You can but the paper, or you can download and print some nice graphing papers.
I used to print those for my children (now in college and beyond).

I will show you how to calculate a few points, put them on a table, plot the points, and draw the line.
(The teacher may prefer a different style, but I hope this helps.

For x=0, y+=+-2%2A0%2B7 --> y=0%2B7 --> y=7
That gives you the point (0,7), with x=0 and y=7.
(That point and the value for y, 7 are often called the y-intercept, because it is the point where the line crosses the y-axis).

For x=3, y=2%2A3%2B7 --> y=6%2B7 --> y=13
That gives you the point (3,13), with x=3 and y=13.

For x=-5, y=2%2A%28-5%29 --> y=-10%2B7 --> y=-3
That gives you the point (-5,-3), with x=-5 and y=-3.

A table with just those 3 points would look like this:
matrix%282%2C4%2Cx%2C-5%2C0%2C3%2Cy%2C-3%2C7%2C13%29
(I made the table horizontal with the x values on the top row, and the corresponding y value below each x value. The teacher may want the table vertical with the x values on the left column, and the y values in another column, each y to the right of the corresponding x).

The graph would look like this:


NOTES:
I made rather big circles around the points (-5,3), (0,7), and (3,13) to make them more visible.
The teacher may like less obvious markings or no visible marking at all.
Not having graph paper, or grid paper, I drew a grid the best way I could do it. Unfortunately, my grid lines do not go through the points calculated, but if I were the teacher, this would be an acceptable graph.