SOLUTION: graphing inequalities, I understand step one, but no further. Example: 3x+7y > 7 change to equals 3x+7y=7 So where do I go from here and how do I get the numbers( ?,?) to p

Algebra ->  Inequalities -> SOLUTION: graphing inequalities, I understand step one, but no further. Example: 3x+7y > 7 change to equals 3x+7y=7 So where do I go from here and how do I get the numbers( ?,?) to p      Log On


   

Question 265318: graphing inequalities, I understand step one, but no further.
Example:
3x+7y > 7
change to equals
3x+7y=7
So where do I go from here and how do I get the numbers( ?,?) to plug ion and be able to graph these questions? I hope that makes sense.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
I'll help you graph 3x%2B7y=7


3x%2B7y=7 Start with the given equation.


7y=7-3x Subtract 3x from both sides.


7y=-3x%2B7 Rearrange the terms.


y=%28-3x%2B7%29%2F%287%29 Divide both sides by 7 to isolate y.


y=%28%28-3%29%2F%287%29%29x%2B%287%29%2F%287%29 Break up the fraction.


y=-%283%2F7%29x%2B1 Reduce.




Looking at y=-%283%2F7%29x%2B1 we can see that the equation is in slope-intercept form y=mx%2Bb where the slope is m=-3%2F7 and the y-intercept is b=1


Since b=1 this tells us that the y-intercept is .Remember the y-intercept is the point where the graph intersects with the y-axis

So we have one point




Now since the slope is comprised of the "rise" over the "run" this means
slope=rise%2Frun

Also, because the slope is -3%2F7, this means:

rise%2Frun=-3%2F7


which shows us that the rise is -3 and the run is 7. This means that to go from point to point, we can go down 3 and over 7



So starting at , go down 3 units


and to the right 7 units to get to the next point



Now draw a line through these points to graph y=-%283%2F7%29x%2B1

So this is the graph of y=-%283%2F7%29x%2B1 through the points and


I'll leave it to you to graph 3x%2B7y%3E7 (ie apply the proper shading)