Expert: Sherman D. - 10/6/2005

Question
Could you recommend me to someone else that can help me out solving it by inverse matrix?
cuz i want to know the answer from this method.
thank you for your kind.
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Followup To
Question -
Hi,
could you please solve the following problem for me ?
An electronics firm produces three products: stereos, home computers, and televisions. Three materials used in each are aluminum (X), steel (Y), and plastic (Z). Requirements to produce one stereo are 5 pounds of aluminum, 6 pounds of steel, and 2 pounds of plastic. For a home computer, requirements are 4 pounds of aluminum, 3 pounds of steel, and 4 pounds of plastic. A television requires 6 pounds of aluminum, 4 pounds of steel, and 5 pounds of plastic. In planning production for the next three months, the firm must know how much of each of the three materials to order. It is anticipated that 20, 000 stereos, 22, 000 home computers, and 30, 000 televisions will be manufactured during this period. Set up the system of equations necessary to estimate basic materials needs. Solve the system by use of the inverse matrix and state purchase requirements for each material. Check your answers by solving by means of the Gauss-Jordan method of elimination.   
thanks ,
Sam
Answer -
5x + 6y + 2z = 20000
4x + 3y + 4z = 22000
6x + 4y + 5z = 30000

This is how i am going to do it, since i don't normally work with inverse matrix.

5x + 6y + 2z = 20000
4x + 3y + 4z = 22000

multiply top by -2

-10x - 12y - 4z = -40000
4x + 3y + 4z = 22000

-6x - 9y = -18000

-3(2x + 3y) = -18000
2x + 3y = 6000
3y = -2x + 6000
y = (-2/3)x + 2000

6x + 4y + 5z = 30000
6x + 4((-2/3)x + 2000) + 5z = 30000
6x + (-8/3)x + 8000 + 5z = 30000
(18/3)x - (8/3)x + 8000 + 5z = 30000
((18 - 8)/3)x + 8000 + 5z = 30000
(10/3)x + 8000 + 5z = 30000
(10/3)x + 5z = 22000
10x + 15z = 66000
15z = -10x + 66000
z = (-2/3)x + 4400

4x + 3y + 4z = 22000
4x + 3((-2/3)x + 2000) + 4((-2/3)x + 4400) = 22000
4x - 2x + 6000 - (8/3)x + 17600 = 22000
(4 - 2 - (8/3))x + 23600 = 22000
((12 - 6 - 8)/3)x + 23600 = 22000
(-2/3)x + 23600 = 22000
(-2/3)x = -1600
-2x = -4800
x = 2400

y = (-2/3)x + 2000
y = (-2/3)(2400) + 2000
y = -1600 + 2000
y = 400

z = (-2/3)x + 4400
z = -1600 + 4400
z = 2800

x = $2400 for aluminum
y = $400 for steel
z = $2800 for plastic

Sorry, but that is how i figured out how to find the answers. Hopefully you can derive the work for yourself from the work i have done.

Answer
www.quickmath.com maybe able to help, but i think at that site it has to be a square matrix.

Since i don't know anyone, try this website.

http://mathforum.org/dr.math/ask/agree.html

just click "I Agree" and you can ask a real person your math question. He has helped me out off and on.