- #1
Mihulik
- 8
- 0
Hi
Let [itex]f:\:\mathbb{Z}_{5}^{3}\rightarrow \mathbb{Z}_{5}^{3}[/itex] be a linear operator and let [itex][f]_{e_{3}}^{e_{3}}=A=\begin{pmatrix}3 & 1 & 4\\
3 & 0 & 2\\
4 & 4 & 3
\end{pmatrix}[/itex] over [itex]\mathbb{Z}_{5}[/itex].
Find a basis B of [itex]\mathbb{Z}_{5}^{3}[/itex] such that [itex][f]_{B}^{B}=\begin{pmatrix}2 & 1 & 0\\
0 & 2 & 0\\
0 & 0 & 2
\end{pmatrix}[/itex].
I found out that the characteristic polynomial of [itex]f[/itex] is [itex]-(\lambda-2)^{3}[/itex] and that there are two linearly indenpendent vectors corresponding to [itex]\lambda =2[/itex].
These vectors are [itex]v_{1}=\begin{pmatrix}1\\
0\\
1
\end{pmatrix}[/itex] and [itex]v_{3}=\begin{pmatrix}4\\
1\\
0
\end{pmatrix}[/itex].
Now, let [itex]B=\left(v_{1},\: v_{2},\: v_{3}\right)[/itex].
We have [itex]f(v_{1})=2\cdot v_{1}[/itex] and [itex]f(v_{3})=2\cdot v_{3}[/itex] as desired.
We want [itex]v_{2}[/itex] to satisfy the equation [itex]Av_{2}=f(v_{2})=v_{1}+2v_{2}[/itex], which we can rewrite as [itex](A-2I_{3})v_{2}=v_{1}[/itex].
However, this is the point I got stuck on.
This equation doesn't have a solution... Why?
I was hopping somebody could tell me what I was doing wrong because I've spent a few hours trying to figure out what's wrong...
Thank you!
Homework Statement
Let [itex]f:\:\mathbb{Z}_{5}^{3}\rightarrow \mathbb{Z}_{5}^{3}[/itex] be a linear operator and let [itex][f]_{e_{3}}^{e_{3}}=A=\begin{pmatrix}3 & 1 & 4\\
3 & 0 & 2\\
4 & 4 & 3
\end{pmatrix}[/itex] over [itex]\mathbb{Z}_{5}[/itex].
Find a basis B of [itex]\mathbb{Z}_{5}^{3}[/itex] such that [itex][f]_{B}^{B}=\begin{pmatrix}2 & 1 & 0\\
0 & 2 & 0\\
0 & 0 & 2
\end{pmatrix}[/itex].
The Attempt at a Solution
I found out that the characteristic polynomial of [itex]f[/itex] is [itex]-(\lambda-2)^{3}[/itex] and that there are two linearly indenpendent vectors corresponding to [itex]\lambda =2[/itex].
These vectors are [itex]v_{1}=\begin{pmatrix}1\\
0\\
1
\end{pmatrix}[/itex] and [itex]v_{3}=\begin{pmatrix}4\\
1\\
0
\end{pmatrix}[/itex].
Now, let [itex]B=\left(v_{1},\: v_{2},\: v_{3}\right)[/itex].
We have [itex]f(v_{1})=2\cdot v_{1}[/itex] and [itex]f(v_{3})=2\cdot v_{3}[/itex] as desired.
We want [itex]v_{2}[/itex] to satisfy the equation [itex]Av_{2}=f(v_{2})=v_{1}+2v_{2}[/itex], which we can rewrite as [itex](A-2I_{3})v_{2}=v_{1}[/itex].
However, this is the point I got stuck on.
This equation doesn't have a solution... Why?
I was hopping somebody could tell me what I was doing wrong because I've spent a few hours trying to figure out what's wrong...
Thank you!