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How to write cramer's rule 3x3 by matlab ?

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ENG. Mohamed Ibrahim
ENG. Mohamed Ibrahim on 10 Mar 2016
Answered: Faith Ira Daro on 24 Nov 2021 at 8:19
How to write cramer's rule 3x3 by matlab ?
  1 Comment
James Tursa
James Tursa on 10 Mar 2016
What have you done so far? Do you know how to replace elements in a matrix with other elements? Do you know how to use a for loop? Do you know how to calculate the determinant of a matrix?

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Answers (2)

Explorer
Explorer on 10 Mar 2016
Edited: Explorer on 10 Mar 2016
Question: Find the system of Linear Equations using Cramers Rule:
2x + y + z = 3
x – y – z = 0
x + 2y + z = 0
The above example is taken from http://www.purplemath.com/modules/cramers.htm
% Demo Code:
A = [2 1 1; 1 -1 -1; 1 2 1] % Coefficient Matrix
X = [3; 0; 0]
Ax = [3 1 1 ; 0 -1 -1;0 2 1 ]
Ay = [2 3 1; 1 0 -1; 1 0 1]
Az = [2 1 3; 1 -1 0; 1 2 0]
detA=det(A)
x = det(Ax)/detA
y = det(Ay)/detA
z = det(Az)/detA
  5 Comments
James Tursa
James Tursa on 15 Jan 2021
Rather than creating the modified matrix with concatenation, a direct assignment of the column:
k = the column number to replace
mNAM = NAM;
mNAM(:,k) = I;
This could easily be put into a loop.

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Faith Ira Daro
Faith Ira Daro on 24 Nov 2021 at 8:19
given the linear equations:
3x+2y = -5
-5x+7y=1
solve for the values of x and y using cramers rule

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