Question 307509:  Perform an operation on the given system that eliminates the indicated variable and solve for the unknown variables. 
x-4y+z=3 
   y-3z=10 
  3y-8z=24 
 Answer by rapaljer(4671)      (Show Source): 
You can  put this solution on YOUR website! Multiply the second equation by -3 and add to the third equation.
 
 
-3y+9z=-30 
3y-8z=24 
z=-6
 
 
Now, substitute z=-6 into the second equation: 
y-3x=10 
y-3*-6=10 
y+18=10 
y=-8
 
 
Finally, substitute both z and y into the first equation: 
x-4y+z=3 
x-4(-8)+-6=3 
x+32-6=3 
x=3+6-32=-23
 
 
I used a program in my TI84 called "POLYSIMULT" to check this answer.  If you are interested in this, send me an Email at rapaljer@seminolestate.edu.
 
 
Dr. Robert J. Rapalje, Retired 
 
 
 
 
 
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