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If $A=\left[\begin{array}{ccc}1 & 0 & 0 \\ 2 & 1 & 0 \\ -3 & 2 & 1\end{array}\right]$ and $B=\left[\begin{array}{ccc}1 & 0 & 0 \\ -2 & 1 & 0 \\ 7 & -2 & 1\end{array}\right]$ then $A B$ equals
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2972 Upvotes
Verified Answer
The correct answer is:
$I$
$I$
$$
\begin{aligned}
& A=\left[\begin{array}{ccc}
1 & 0 & 0 \\
2 & 1 & 0 \\
-3 & 2 & 1
\end{array}\right], B=\left[\begin{array}{ccc}
1 & 0 & 0 \\
-2 & 1 & 0 \\
7 & -2 & 1
\end{array}\right] \\
& A B=\left[\begin{array}{lll}
1 & 0 & 0 \\
0 & 1 & 0 \\
0 & 0 & 1
\end{array}\right]=I
\end{aligned}
$$
\begin{aligned}
& A=\left[\begin{array}{ccc}
1 & 0 & 0 \\
2 & 1 & 0 \\
-3 & 2 & 1
\end{array}\right], B=\left[\begin{array}{ccc}
1 & 0 & 0 \\
-2 & 1 & 0 \\
7 & -2 & 1
\end{array}\right] \\
& A B=\left[\begin{array}{lll}
1 & 0 & 0 \\
0 & 1 & 0 \\
0 & 0 & 1
\end{array}\right]=I
\end{aligned}
$$
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