document.write( "Question 173706: Please show me how to solve. I'm having trouble understanding from when I asked a few days ago.\r
\n" ); document.write( "\n" ); document.write( "Solve by graphing.
\n" ); document.write( "3x + 4y ≤ 12
\n" ); document.write( "x + 3y ≤ 6
\n" ); document.write( "x ≥ 0
\n" ); document.write( "y ≥ 0
\n" ); document.write( "

Algebra.Com's Answer #128625 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
Solve by graphing.
\n" ); document.write( "3x + 4y ≤ 12
\n" ); document.write( "x + 3y ≤ 6
\n" ); document.write( "x ≥ 0
\n" ); document.write( "y ≥ 0\r
\n" ); document.write( "\n" ); document.write( ":
\n" ); document.write( "Plot the 1st two equations, put the equations in the slope/intercept form
\n" ); document.write( "3x + 4y =< 12
\n" ); document.write( "4y = 12 - 3x
\n" ); document.write( "y = \"12%2F4\" - \"3%2F4\"x
\n" ); document.write( "y = \"-3%2F4\"x + 3
\n" ); document.write( ":
\n" ); document.write( "Calculate two points (substitute the values for x and find y):
\n" ); document.write( " x | y
\n" ); document.write( "-------
\n" ); document.write( " 0 | 4
\n" ); document.write( " 4 | 1
\n" ); document.write( "Graph should look like this:
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-4%2C+5%2C+-4%2C+6%2C+-.75x%2B4%29+\"
\n" ); document.write( ":
\n" ); document.write( "Do the same with the 2nd equation
\n" ); document.write( "x + 3y => 6
\n" ); document.write( "3y = 6 - x
\n" ); document.write( "y = \"6%2F3\" - \"x%2F3\"
\n" ); document.write( "y = -\"1%2F3\"x + 2
\n" ); document.write( "Calculate two points (substitute the values for x and find y):
\n" ); document.write( " x | y
\n" ); document.write( "-------
\n" ); document.write( " 0 | 2
\n" ); document.write( " 3 | 1
\n" ); document.write( "Graph should look like this:
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-4%2C+5%2C+-4%2C+6%2C+-.33x%2B2%29+\"
\n" ); document.write( ":
\n" ); document.write( "The last two equations tell you that only positive values for x and y are considered
\n" ); document.write( ":
\n" ); document.write( "Put both graphs on the same coordinate system:
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-4%2C+5%2C+-4%2C+6%2C+-.75x%2B4%2C+-.33x%2B2%29+\"
\n" ); document.write( "Look at this graph
\n" ); document.write( "The 1st equation:3x + 4y =< ; 12, the purple line
\n" ); document.write( "Area of feasibility is at or below this line
\n" ); document.write( ":
\n" ); document.write( "The 2nd equation: x + 3y => 6, green line
\n" ); document.write( "Area of feasibility is at or above this line
\n" ); document.write( ":
\n" ); document.write( "x => 0
\n" ); document.write( "y => 0
\n" ); document.write( "As I said before, this means only positive values for x & y, inside the area of feasibility are considered.
\n" ); document.write( ":
\n" ); document.write( "The solution is the triangular area between the lines and to the right of the y axis.
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