Monday, September 19, 2011

EA 1 graphing project more hints 9-19

Solve for the coordinates of the vertex where red crosses green
Use the red equation in a system with the green equation
4x + 8y = 2400 and
9x + 3y = 1800                         
Hint - make the equations simpler; divide the 1st equation by 4

x + 2y = 600

and divide the second equation by 3.

3x + y = 600

Then use an "x =" or a "y =" to substitute, for example

x = 600 - 2y
make x tmporarily go away
3(600 - 2y) + y = 600     by substituting for x next to the 3
1800 - 6y + y = 600     by distribution
1800 - 5y = 600     by combining "y" terms
-5y = -1200     by subtracting 1800 from each side
y = 240    by dividing by -5 on each side
bring back x
x = 600 - 2(240)     by substituting for y in the earlier equation
x = 600 - 480
x = 120
the solution (x,y)  where these graphs intersect is (120, 240)
(120, 240) is a vertex for the feasible region


Solve for the coordinates of the vertex where green crosses blue
Use the green equation in a system with the blue equation
9x + 3y = 1800 and
9x + y = 1700                           
Hint - use a "y = " equation to substitute

y = 1700 - 9x     by subtracting 9x from each side
make y go away temporarily
9x + 3(1700 - 9x) = 1800     by substituting for y next to the 3
9x + 5100 - 27x = 1800     by distributing
-18x + 5100 = 1800     by combining "x" terms
-18x = -3300     by subtracting 5100 from each side
x = 183     by dividing each side by -18
bring back y
9(183) + y = 1700     by substituting 183 for x next to the 9 in the earlier equation
1647 + y = 1700     by multiplying
y = 53     by subtracting 1647 from both sides
        
the solution (x,y)  where these graphs intersect is (183, 53)
(183, 53) is a vertex for the feasible region

The calculated vertices for the feasible region are (0,0), (0, 300), (120, 240), (183, 53) and (200,)
These are the combinations of the numbers of games made at plant 1 and plant 2 that you will use to test in the objective function P = 90x + 70y.

Plug in all five ordered pairs and see which one gives you a maximum value for P.

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