graphing inequalities in two variables

[Ttvietnamese]

I have been going around to like 2 million websites and like 100 teachers trying to understand this. Every source i have gone to aren't specific or understandable and my head is about to explode because of the hundreds of ways my teachers showed me. So how would your graph an equation like x+2y<-6? I know when to use a dashed line and a solid line, however, I don't know which side to shade in. I get bits and pieces of the y-intercept and the slope method. But i still need to like review it. So far this website is useful but I still don't get it. http://www.math.com/school/subject2/lessons/S2U4L3GL.html Please reply soon soon before my head EXPLODES which will be soon.

 

[tkhunny]

Hint #1 - If you see EQUALS, draw a solid line. Otherwise, draw a broken line.

Hint #2 - Stop fretting over which side to shade. TRY something. Often, the point (0,0) is not on the line. Try (0,0). Does it work? Shade the side with (0,0) in it. Does it fail? Shade the other side. If (0,0) IS on the line, pick something else that looks easy.

Hint #3 - If you are not sufficiently familiar with the slope-intercept form, you will need to review that with great care.

 

[Mrspi]

I have been going around to like 2 million websites and like 100 teachers trying to understand this. Every source i have gone to aren't specific or understandable and my head is about to explode because of the hundreds of ways my teachers showed me. So how would your graph an equation like x+2y<-6? I know when to use a dashed line and a solid line, however, I don't know which side to shade in. I get bits and pieces of the y-intercept and the slope method. But i still need to like review it. So far this website is useful but I still don't get it. http://www.math.com/school/subject2/lessons/S2U4L3GL.html Please reply soon soon before my head EXPLODES which will be soon.

Wow!!! 2 million websites and 100 teachers??? And you still don't understand it?

Let me try.

An inequality of the form
ax + by < c or
ax + by <= c or
ax + by > c or
ax + by >= c

represents the points on one side of a line (the points on the line may be included if you have <= or <=).

Graph the line. If the inequality includes the = possibility (like <= or <=), then draw the line as a solid line. If not, draw it as a dashed line. Then, you need to decide which side of the line to shade. thhunny has given you a GREAT suggestion. Pick a point that is not on the boundary line, and check its coordinates in the original inequality. If the coordinates of that point satisfy the inequality, shade the region which contains the test point; if the inequality is not true for the coordinates of the test point, shade the OTHER side of the line.

This is not rocket science....