Question 117186
Graph <font color = "green">y > 2x + 1</font> and <font color = "blue">2x + y > 2</font>
<pre><font size = 3><b>
First graph only the first boundary line, which is the
first inequality with the > replaced by =.  That is the
line whose equation is <font color = "green">y = 2x + 1</font>

So we draw the graph of the first boundary line by getting 
a couple of points.  We draw a <font color = "green">GREEN</font> dotted line through them, 
dotted because of the >.  (If it had been <u>></u> we would 
have drawn the boundary line solid.)

{{{ drawing(400,400,-10,10,-10,10,
graph(400,400,-10,10,-10,10,0,(2x+1)( sqrt(sin(5x)) )/ ( sqrt(sin(5x))) )
)}}}

Before we draw the other boundary line, we must
decide which side of the line the final shading
must be on.  To do this we choose any point which 
is not on the line as a test point.  Let's 
arbitrarily choose (3,3) on the right side of the
line as a test point. Substitute x=3, y=3 into the 
original inequality:

<font color = "green">y > 2x+1</font>
3 > 2(3)+1
3 > 6+1
3 > 7

This is FALSE, so we shade the OPPOSITE side of
the line from which (3,3) is on, which is
the LEFT side of the <font color = "green">GREEN</font> line.

Next we graph the second boundary line, which is the
second inequality with the > replaced by =. 

<font color = "blue">2x + y = 2</font>

So we draw the graph of the second boundary line by getting 
a couple of points.  We draw a <font color = "blue">BLUE</font> dotted line through them,
dotted because of the >.  (Again, if it had been <u>></u> we 
would have drawn the boundary line solid.)

{{{ drawing(400,400,-10,10,-10,10,
graph(400,400,-10,10,-10,10,0,(2x+1)( sqrt(sin(5x)) )/ ( sqrt(sin(5x))),
(2-2x)( sqrt(sin(5x)) )/ ( sqrt(sin(5x)))

 )
)}}}

As before must decide which side of the <font color = "blue">BLUE</font> line 
the final shading must be on.  To do this we choose 
any point which is not on the <font color = "blue">BLUE</font> line as a test 
point.  Let's arbitrarily choose (4,2) on the right 
side of the <font color = "blue">BLUE</font> line as a test point. Substitute 
x=4, y=2 into the original inequality:

    <font color = "blue">2x + y > 2</font>
2(4) + (2) > 2
     8 + 2 > 2
        10 > 2


This is TRUE, so we DO shade the side of
the <font color = "blue">BLUE</font> line which (4,2) lie on, which is
the RIGHT side of the <font color = "blue">BLUE</font> line.
  
So we must shade the V-shaped wedge which is
LEFT of the <font color = "green">GREEN</font> line and RIGHT of the <font color = "blue">BLUE</font>
LINE, as indicated below:

{{{ drawing(400,400,-10,10,-10,10, locate(-2,8,"SHADE_THIS"),
locate(-2,7,"WEDGE_ONLY"),
graph(400,400,-10,10,-10,10,0,(2x+1)( sqrt(sin(5x)) )/ ( sqrt(sin(5x))),
(2-2x)( sqrt(sin(5x)) )/ ( sqrt(sin(5x))) )
)}}}

Edwin</pre>