- #1
zecuria
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Homework Statement
Let x1 = (1, 2, -1, 1), x2 = (-1, -1, -1, -1), x3 = (1, 1, 1, 0), x4 = (-2, -1 -4 -1)
Show that x1, x3 and x4 are linearly independent
Homework Equations
The Attempt at a Solution
Now I used the equation:
ax1+bx2+cx3+dx4=0
Hence forth the augmented matrix of the equation is,
[tex]
\begin{pmatrix}
1 & -1 & 1 & -2 & | & 0\\
2 & -1 & 1 & -1 & | & 0\\
-1 & -1 & 1 & -4 & | & 0\\
1 & -1 & 0 & -1 & | & 0
\end{pmatrix}
[/tex]
This is row reduced to,
[tex]
\begin{pmatrix}
1 & -1 & 1 & -2 & | & 0\\
0 & 1 & -1 & 3 & | & 0\\
0 & 0 & -1 & 1 & | & 0\\
0 & 0 & 0 & 0 & | & 0
\end{pmatrix}
[/tex]
From as there is no leading entry corresponding to d, Setting d = t, the general solution is:
a = -t, b = -2t, c = t, d = t.
And as the number of leading entries =! number of unknowns so the vectors are linearly dependant
This is the point where I get confused as the question asks how they are linearly independant so I am quite confused at this point
Any help would be most appreciated and thanks in advanced