Answer on Question #46675 – Math – Linear Algebra
Question:
Solve the system of equations using Gauss-Jordan method with pivoting.
10 x 1 + x 2 + x 3 = 12 10x_1 + x_2 + x_3 = 12 10 x 1 + x 2 + x 3 = 12 10 x 1 + x 2 + x 3 = 12 10x_1 + x_2 + x_3 = 12 10 x 1 + x 2 + x 3 = 12 10 x 1 + x 2 + x 3 = 12 10x_1 + x_2 + x_3 = 12 10 x 1 + x 2 + x 3 = 12
Solution:
Rewrite the system in matrix form and solve it by Gaussian Elimination (Gauss-Jordan elimination)
( 10 1 1 12 10 1 1 12 10 1 1 12 ) \left( \begin{array}{ccccc} 10 & 1 & 1 & 12 \\ 10 & 1 & 1 & 12 \\ 10 & 1 & 1 & 12 \end{array} \right) ⎝ ⎛ 10 10 10 1 1 1 1 1 1 12 12 12 ⎠ ⎞
divide the 1-th row by 10
( 1 0.1 0.1 1.2 10 1 1 12 10 1 1 12 ) \left( \begin{array}{ccccc} 1 & 0.1 & 0.1 & 1.2 \\ 10 & 1 & 1 & 12 \\ 10 & 1 & 1 & 12 \end{array} \right) ⎝ ⎛ 1 10 10 0.1 1 1 0.1 1 1 1.2 12 12 ⎠ ⎞
from 2; 3 rows we subtract the 1-th row, multiplied respectively by 10; 10
( 1 0.1 0.1 1.2 0 0 0 0 0 0 0 0 ) \left( \begin{array}{ccccc} 1 & 0.1 & 0.1 & 1.2 \\ 0 & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 \end{array} \right) ⎝ ⎛ 1 0 0 0.1 0 0 0.1 0 0 1.2 0 0 ⎠ ⎞
Answer: x 1 + ( 0.1 ) x 2 + ( 0.1 ) x 3 = 1.2 x_1 + (0.1)x_2 + (0.1)x_3 = 1.2 x 1 + ( 0.1 ) x 2 + ( 0.1 ) x 3 = 1.2
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