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Chikis August 14th, 2018 10:12 PM

matrix method for simultaneous equations
 
I have used matrix method of solving simultaneous equation on these
x + y + z = 5
2x - y + 3z = 16
3x + 2y - z = 3.
All the results I get when substituted into the original equation does not tarry with what is on ground, until I used the old traditional method and got x = -9, y = 2, z = 12,
and substituted the values to the original equations and it worked.
Now my take is that you cannot use matrix method or Cramer rule to solve the equation. If I am lying, prove me wrong. Am ready to learn maybe if I missed something along the line when solving.

Joppy August 15th, 2018 12:19 AM

You might like to play around here. The solutions have working attached.

topsquark August 15th, 2018 12:44 AM

Quote:

Originally Posted by Chikis (Post 597691)
I have used matrix method of solving simultaneous equation on these
x + y + z = 5
2x - y + 3z = 16
3x + 2y - z = 3.
All the results I get when substituted into the original equation does not tarry with what is on ground, until I used the old traditional method and got x = -9, y = 2, z = 12,
and substituted the values to the original equations and it worked.
Now my take is that you cannot use matrix method or Cramer rule to solve the equation. If I am lying, prove me wrong. Am ready to learn maybe if I missed something along the line when solving.

Your solution doesn't work. Is there a typo? W|A (here) and I (I verified W|A's result by Cramer's rule) get x = 35/13, y = -12/13, z = 42/13.

-Dan

skipjack August 15th, 2018 01:25 AM

Quote:

Originally Posted by Chikis (Post 597691)
I used the old traditional method and got x = -9, y = 2, z = 12,
and substituted the values to the original equations and it worked.

In that case, your third equation was 3x + 21y - z = 3, not 3x + 2y - z = 3.


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