Solution.
v+2w−2x−y=0
2v+3w−5x+y−7z=0
w+x−y+z=0
−v+w+5x−y=0
⎣⎡120−12311−2−515−11−1−10−7100000⎦⎤
Find the pivot in the 1st column in the 1st row
⎣⎡120−12311−2−515−11−1−10−7100000⎦⎤
Eliminate the 1st column
⎣⎡10002−113−2−113−13−1−20−7100000⎦⎤
Find the pivot in the 2nd column in the 2nd row (inversing the sign in the whole row)
⎣⎡10002113−2113−1−3−1−207100000⎦⎤
Eliminate the 2nd column
⎣⎡10000100−41005−327−147−6−210000⎦⎤
Make the pivot in the 4th column by dividing the 3rd row by 2
⎣⎡10000100−41005−317−147−3−210000⎦⎤
Eliminate the 4th column
⎣⎡10000100−410000101−2−300000⎦⎤
Solution set:
v=4x−z;w=−x+2z;y=3z;x,z−free.
Answer: v=4x−z;w=−x+2z;y=3z;x,z−free.
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