- #1
SmellyGoomba
- 2
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Homework Statement
Find A if (2A-1 - 3I)T =
2*[tex]
\begin{pmatrix}
-1 & 2\\
5 & 4
\end{pmatrix}
[/tex]
Homework Equations
The Attempt at a Solution
I have no idea if I'm even on the right track of solving this question...
I simplified the right hand side down to
[tex]
\begin{pmatrix}
-2 & 4\\
10 & 8
\end{pmatrix}
[/tex]
I took the transpose of both sides so the left hand side is just (2A-1 - 3I)
The right hand side is now
[tex]
\begin{pmatrix}
-2& 10\\
4 & 8
\end{pmatrix}
[/tex]
I multiplied both sides by A so
LH: A(2A-1 - 3I)
RH: A*[tex]
\begin{pmatrix}
-2& 10\\
4 & 8
\end{pmatrix}
[/tex]
Distribute the A so
LH: (A2A-1 - A3I) => (2I - A3I)
Bring the A3I part to the right side
LH = 2I
RH = A3I + A*[tex]
\begin{pmatrix}
-2& 10\\
4 & 8
\end{pmatrix}
[/tex]
Simplify the A3I part on the right hand side to get
A * [tex]
\begin{pmatrix}
3 & 0\\
0 & 3
\end{pmatrix}
[/tex]
Factor out the A on the right hand side to get
A * ([tex]
\begin{pmatrix}
-2 & 10\\
4 & 8
\end{pmatrix}
[/tex]
+
[tex]
\begin{pmatrix}
3 & 0\\
0 & 3
\end{pmatrix}
[/tex]
)
Add the two matrices together in the brackets to get
A * [tex]\begin{pmatrix}
1 & 10\\
4 & 11
\end{pmatrix}
[/tex]
So I'm left with
[tex]
\begin{pmatrix}
2 & 0\\
0 & 2
\end{pmatrix}
[/tex]
=
A *
[tex]
\begin{pmatrix}
1 & 10\\
4 & 11
\end{pmatrix}
[/tex]
Now there's no way I can somehow get A like that so I screwed up somewhere in there.. probably from the start lol
This looks so messy... am I allowed to upload my handwritten work on a site then post it here? Seems like a better alternative to the mess I have up there >_> Anyways I'm not really looking for a step by step on how to do this. Just a push in the right direction is all...