SOLUTION: Determine the augmented matrix:p+s+c=600; 12p+10s+8c=5900; 0-s+c=175 Solve for the matrix and please show all work.

Algebra ->  Matrices-and-determiminant -> SOLUTION: Determine the augmented matrix:p+s+c=600; 12p+10s+8c=5900; 0-s+c=175 Solve for the matrix and please show all work.       Log On


   



Question 143429: Determine the augmented matrix:p+s+c=600; 12p+10s+8c=5900; 0-s+c=175
Solve for the matrix and please show all work.

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
Determine the augmented matrix:p+s+c=600; 12p+10s+8c=5900; 0-s+c=175
Solve for the matrix and please show all work.


++p%2B++s%2B+c+=+++600
12p%2B10s%2B8c+=+5900
0++-s%2B+c+=++175 

Solve for the matrix and please show all work. 

Put in all the 1 coefficients and make the 0 a 0p

1p%2B1s%2B1c=600
12p%2B10s%2B8c=5900
0p-1s%2B1c=175

Now erase all the letters and you have



The idea is to get three 0's in the lower left corner:
Multiply the top row through by -12



Add the top row to the middle row:



Restore the top row



Multiply the bottom row by -2


Add the middle row to the bottom row:



Now we've gotten three 0's in the bottom left.
So we make the matrix back into 3 equations:

1p%2B1s%2B1c=600
0p-2s-4c=-1300
0p%2B0s-6c=-1650

Drop the 0 terms and make the 1's invisible:

p%2Bs%2Bc=600
-2s-4c=-1300
-6c=-1650

Solve from the bottom to top.
Solve the bottom equation for c

-6c=-1650
%28-6c%29%2F%28-6%29=%28-1650%29%2F%28-6%29
c=275

Plug that into the second equation:

-2s-4c=-1300
-2s-4%28275%29=-1300
-2s-1100=-1300
-2s=-200
%28-2s%29%2F%28-2%29=%28-200%29%2F%28-2%29
s=100

Plug that and c=275 into the first
equation:

p%2Bs%2Bc=600
p%2B100%2B275=600
p%2B375=600
p=225

So

(p,s,c) = (225,100,275)

Edwin