Need help on matrices using cramer's rule

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Discussion Overview

The thread discusses solving a system of equations using Cramer's rule, specifically focusing on the equations: x - y + 3z = 8, 3x + y - 2z = -2, and 2x + 4y + z = 0. Participants explore the correctness of a proposed solution and the nature of the equations involved, including whether they are dependent.

Discussion Character

  • Mathematical reasoning
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant proposes a solution of x = 1, y = -1, z = 2 and questions whether the equations represent dependent equations.
  • Another participant confirms that the solution satisfies all equations and asserts it is unique due to the non-zero determinant of the coefficient matrix.
  • A third participant provides a detailed step-by-step solution using an online calculator, presenting calculations for determinants and confirming the solution found.
  • A later reply seeks clarification on the initial question about the nature of the equations, indicating some confusion regarding the terminology used.

Areas of Agreement / Disagreement

Participants generally agree that the proposed solution satisfies the equations and is unique, but there is some confusion regarding the classification of the equations as dependent or independent.

Contextual Notes

There is uncertainty regarding the terminology used to describe the equations, and the discussion does not resolve whether the equations are dependent or independent.

qdv
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I am learning how to solve a matrice using cramer's rule, and not sure if this is the correct answer.

Solve the following systems of equations
x - y + 3z = 8
3x + y - 2z = -2
2x + 4y + z = 0
so I figured out the solution is x = 1, y = -1, z = 2

but is this equation consider a
dependent equation that all solutions that satisfy x - y + 3z = 8 ??

thanks
 
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qdv said:
I am learning how to solve a matrice using cramer's rule, and not sure if this is the correct answer.

Solve the following systems of equations
x - y + 3z = 8
3x + y - 2z = -2
2x + 4y + z = 0
so I figured out the solution is x = 1, y = -1, z = 2

thanks

It's okay.The solution satisfies all equations and it's unique,therefore...Congratulations! :smile:

Daniel.
 
Online calculator

I solve it using a online calculator and I got

Cramer rule's solver step by step
Coeficients Matrix
1 -1 3 8
3 1 -2 -2
2 4 1 0
Δ = determinant1 -1 3
3 1 -2
2 4 1
Δ sub x = det8 -1 3
-2 1 -2
0 4 1
Δ sub y = det1 8 3
3 -2 -2
2 0 1
Δ sub z = det1 -1 8
3 1 -2
2 4 0
Δ = det1 -1 3
3 1 -2
2 4 1
1 -1 3
3 1 -2

[(1) (1) (1) + (3) (4) (3) + (2) (-1) (-2)] - [(3) (-1) (1) + (1) (4) (-2) + (2) (1) (3)]
(1) + (36) + (4)- (-3) + (-8) + (6)
( 41) - ( -5)
Δ = 46

Δx = det8 -1 3
-2 1 -2
0 4 1
8 -1 3
-2 1 -2

[(8) (1) (1) + (-2) (4) (3) + (0) (-1) (-2)] - [(-2) (-1) (1) + (8) (4) (-2) + (0) (1) (3)]
(8) + (-24) + (0)- (2) + (-64) + (0)
( -16) - ( -62)
Δx = 46

Δy = det1 8 3
3 -2 -2
2 0 1
1 8 3
3 -2 -2

[(1) (-2) (1) + (3) (0) (3) + (2) (8) (-2)] - [(3) (8) (1) + (1) (0) (-2) + (2) (-2) (3)]
(-2) + (0) + (-32)- (24) + (0) + (-12)
( -34) - ( 12)
Δy = -46

Δz = det1 -1 8
3 1 -2
2 4 0
1 -1 8
3 1 -2

[(1) (1) (0) + (3) (4) (8) + (2) (-1) (-2)] - [(3) (-1) (0) + (1) (4) (-2) + (2) (1) (8)]
(0) + (96) + (4)- (0) + (-8) + (16)
( 100) - ( 8)
Δz = 92

x =46/46

y =-46/46

z =-46/46

x =1

y =-1

z =2

-------
www.algebrasolver.totalh.com
 
Last edited:
qdv said:
I am learning how to solve a matrice using cramer's rule, and not sure if this is the correct answer.

Solve the following systems of equations
x - y + 3z = 8
3x + y - 2z = -2
2x + 4y + z = 0
so I figured out the solution is x = 1, y = -1, z = 2

but is this equation consider a
dependent equation that all solutions that satisfy x - y + 3z = 8 ??

thanks
What do you mean by "this equation"? It's not at all clear what your question is. Yes, as dextercioby said, and you could easily have checked, x= 1, y= -1, z= 2 satisfies the three equations and, since the determinant of coefficients is not 0, is the only solution to that system of equations.
 

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