SOLUTION: Hello. I am having such a hard time understanding how to graph linear inequalities, from solving the problem to understanding where the points go on the x and y axis, if the line s

Algebra ->  Graphs -> SOLUTION: Hello. I am having such a hard time understanding how to graph linear inequalities, from solving the problem to understanding where the points go on the x and y axis, if the line s      Log On


   



Question 405570: Hello. I am having such a hard time understanding how to graph linear inequalities, from solving the problem to understanding where the points go on the x and y axis, if the line should be solid or dashed. I just can't make it click in my brain. Can you possibly show a very blunt breakdown of the following two equations? If I can follow it step by step I should be able to get it. Thank you so much!
1.) Graph 2x + y < 4
2.) Graph 4x - 3y >= 12

Found 2 solutions by stanbon, ewatrrr:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
1.) Graph 2x + y < 4
Solve for "y":
y < -2x+4
----
You NEVER graph an inequality directly.
You graph its boundary which is always an equality.
Graph y = -2x+4 as a dashed line because equality
is not part of your problem.
---
Plot: (0,4) and (1,2) and draw a dashed line thru them
----
Since you want y LESS than the boundary, shade
the half-plane BELOW the boundary to get the graph
of the inequality:
graph%28400%2C300%2C-10%2C10%2C-10%2C10%2Cy+%3C+-2x%2B4%29
====================
2.) Graph 4x - 3y >= 12
Solve for "y":
3y <= 4x-12
y <= (4x-12)/3
---
Now graph the boundary as a solid
line because it is part of the problem
Plot (0,-4)(2,-4/3)
---
Shade the half-plane BELOW the boundary
because you want y LESS than the boundary.
The line and the shaded area are the graph.
graph%28400%2C300%2C-10%2C10%2C-10%2C10%2C%284x-12%29%2F3%2Cy%3C%284x-12%29%2F3%29
=============================================
Cheers,
Stan H.

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi
2x + y < 4 OR y < -2x + 4
I. Graph line y = -2x + 4 by plotting points a couple of points(0,4) and (1,2)
for ex and connect with a 'dotted line' due to the < sign. (cannot demonstate that here)

II. Shade below the dotted line to show the graph of the Inequality
Solved by pluggable solver: Plot Any Inequality
Graphing function y%3C-2x%2B4:

graph%28+300%2C+300%2C+-10%2C+10%2C+-8%2C+12%2C+y%3C-2x%2B4+%29