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- 2071 Bhadra · 8 marks
Gauss elimination/Jordan with pivoting
Short answer
Applying Gauss-Jordan elimination with partial pivoting, the augmented matrix reduces to the identity, yielding the solution x = 2.0909, y = 0.1818, z = -1.3636.
Solve the following linear equations using Gauss Elimination or Gauss Jordan method using partial pivoting. 2x + 3y + 2z = 2 10x + 3y + 4z = 16 3x + 6y + z = 6
Gauss-Jordan method with partial pivoting: at every stage the largest element (in absolute value) of the pivot column is moved to the pivot position by a row swap, the pivot row is divided by the pivot to make it 1, and the other entries of that column (above and below) are made 0. The final matrix is the identity, so the right column is the solution.
Step 1: System
2x + 3y + 2z = 2
10x + 3y + 4z = 16
3x + 6y + z = 6
Step 2: Reduce to the identity form
Augmented matrix [A | b]:
2.0000 3.0000 2.0000 | 2.0000
10.0000 3.0000 4.0000 | 16.0000
3.0000 6.0000 1.0000 | 6.0000
Column 1: largest pivot is in row 2, so swap R1 ↔ R2:
10.0000 3.0000 4.0000 | 16.0000
2.0000 3.0000 2.0000 | 2.0000
3.0000 6.0000 1.0000 | 6.0000
R1 ← R1 / 10.0000:
1.0000 0.3000 0.4000 | 1.6000
2.0000 3.0000 2.0000 | 2.0000
3.0000 6.0000 1.0000 | 6.0000
R2 ← R2 − (2.0000) R1; R3 ← R3 − (3.0000) R1:
1.0000 0.3000 0.4000 | 1.6000
0.0000 2.4000 1.2000 | -1.2000
0.0000 5.1000 -0.2000 | 1.2000
Column 2: largest pivot is in row 3, so swap R2 ↔ R3:
1.0000 0.3000 0.4000 | 1.6000
0.0000 5.1000 -0.2000 | 1.2000
0.0000 2.4000 1.2000 | -1.2000
R2 ← R2 / 5.1000:
1.0000 0.3000 0.4000 | 1.6000
0.0000 1.0000 -0.0392 | 0.2353
0.0000 2.4000 1.2000 | -1.2000
R1 ← R1 − (0.3000) R2; R3 ← R3 − (2.4000) R2:
1.0000 0.0000 0.4118 | 1.5294
0.0000 1.0000 -0.0392 | 0.2353
0.0000 0.0000 1.2941 | -1.7647
R3 ← R3 / 1.2941:
1.0000 0.0000 0.4118 | 1.5294
0.0000 1.0000 -0.0392 | 0.2353
0.0000 0.0000 1.0000 | -1.3636
R1 ← R1 − (0.4118) R3; R2 ← R2 − (-0.0392) R3:
1.0000 0.0000 0.0000 | 2.0909
0.0000 1.0000 0.0000 | 0.1818
0.0000 0.0000 1.0000 | -1.3636
Step 3: Solution
From the final matrix (identity on the left), the unknowns are read directly:
x = 2.0909
y = 0.1818
z = -1.3636
Answer: x = 2.0909, y = 0.1818, z = -1.3636
✓ Answer checked by Claude Opus 5.5 (high effort)
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