Find the Products AB and BA to Determine Whether B $$A = \left[ \begin{array} { r r r r } 1 & - 2 & 0 & 0 \\0 & 1 & - 2 & 0 \\0 & 0 & 1 & 9 \\0 & 0 & 0 & 1\end{array} \right]$$

question 141

Multiple Choice

Find the products AB and BA to determine whether B is the multiplicative inverse of A.
- $$A = \left[ \begin{array} { r r r r } 1 & - 2 & 0 & 0 \\0 & 1 & - 2 & 0 \\0 & 0 & 1 & 9 \\0 & 0 & 0 & 1\end{array} \right]$$

• A) \(\left[ \begin{array} { c c c c } 1 & 2 & 4 & - 36 \\ 0 & 1 & 2 & - 18 \\ 0 & 0 & 1 & - 9 \\ 0 & 0 & 0 & 1 \end{array} \right]\)
• B)
• \[\left[ \begin{array} { r r r r }
• 1 & - 9 & 18 & - 36 \\
• 0 & 1 & 2 & - 4 \\
• 0 & 0 & 1 & 2 \\
• 0 & 0 & 0 & 1
• \end{array} \right]\]
• C)
• \[\left[ \begin{array} { r r r r }
• 1 & 0 & 0 & 0 \\
• - 9 & 1 & 0 & 0 \\
• 18 & 2 & 1 & 0 \\
• - 36 & - 4 & 2 & 1
• \end{array} \right]\]
• D)
• \[\left[ \begin{array} { r r r r }
• 1 & 0 & 0 & 0 \\
• 2 & 1 & 0 & 0 \\
• 4 & 2 & 1 & 0 \\
• - 18 & - 18 & - 9 & 1
• \end{array} \right]\]

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