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How do you solve using Gaussian elimination or Gauss-Jordan elimination:

2x + 5y - 2z = 14 5x - 6y + 2z = 0 4x - y + 3z = -7






Profile image of Aniket Singh
1 Year agoGrade
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1 Answer

Profile image of Askiitians Tutor Team
1 Year ago

To solve this system of linear equations using Gaussian elimination or Gauss-Jordan elimination, you'll need to perform a series of row operations to transform the system into row-echelon form (also known as triangular form) and then back-substitute to find the values of x, y, and z.

Here are the original equations for reference:

2x + 5y - 2z = 14
5x - 6y + 2z = 0
4x - y + 3z = -7
We'll start by performing the row operations to eliminate variables from equations. The goal is to get zeros below the main diagonal.

Step 1: Eliminate x from Equation 2 and Equation 3 by subtracting a multiple of Equation 1:

Multiply Equation 1 by 5 and subtract it from Equation 2:
(5)(2x + 5y - 2z) = 5(14)
10x + 25y - 10z = 70
-(10x - 12y + 4z = 0) (Equation 2)

Now, add Equation 2 and Equation 3:
(10x + 25y - 10z) + (10x - 12y + 4z) = 70 + (-7)
(10x + 10x) + (25y - 12y) + (-10z + 4z) = 63
20x + 13y - 6z = 63 (Equation 4)

So, after these operations, we have the following system:

2x + 5y - 2z = 14
10x - 12y + 4z = 0
20x + 13y - 6z = 63
Step 2: Continue to eliminate x from Equation 3 by subtracting a multiple of Equation 1:

Multiply Equation 1 by 10 and subtract it from Equation 3:
(10)(2x + 5y - 2z) = 10(14)
20x + 50y - 20z = 140
-(20x + 13y - 6z = 63) (Equation 3)

Now, add Equation 3 and the updated Equation 3:
(20x + 50y - 20z) + (20x + 13y - 6z) = 140 + 63
(20x + 20x) + (50y + 13y) + (-20z - 6z) = 203
40x + 63y - 26z = 203 (Equation 5)

So, after these operations, we have the following system:

2x + 5y - 2z = 14
10x - 12y + 4z = 0
40x + 63y - 26z = 203
Now, the system is in row-echelon form. To find the solution, you can start with the last equation (Equation 5) and work your way up, back-substituting the values of y, z, and then x.

Starting with Equation 5:
40x + 63y - 26z = 203

Now, solve for x:
40x = 203 - 63y + 26z
x = (203 - 63y + 26z)/40

Now, you can substitute this expression for x into Equation 2 (10x - 12y + 4z = 0) to solve for y and z.