Find the Inverse of the Matrix $$\left[ \begin{array} { c c c } 7 & 7 & 7 \\21 & 35 & 28 \\21 & 42 & 35\end{array} \right]$$

question 7

Multiple Choice

Find the inverse of the matrix $$\left[ \begin{array} { c c c } 7 & 7 & 7 \\21 & 35 & 28 \\21 & 42 & 35\end{array} \right]$$ . ​

• A)​ \[\frac { 1 } { 7 } \left[ \begin{array} { c c c }
• 1 & 1 & - 1 \\
• - 3 & 2 & - 1 \\
• 3 & - 3 & 2
• \end{array} \right]\]
• B)​ \[\frac { 1 } { 7 } \left[ \begin{array} { c c c }
• 1 & 1 & 1 \\
• 0 & - 2 & - 1 \\
• 3 & - 3 & 2
• \end{array} \right]\]
• C)​ \[- 7 \left[ \begin{array} { c c c }
• 3 & 1 & 0 \\
• - 3 & 1 & - 1 \\
• 1 & - 3 & 2
• \end{array} \right]\]
• D)​ \[- \frac { 1 } { 7 } \left[ \begin{array} { c c c }
• 1 & 0 & - 1 \\
• - 3 & 2 & - 1 \\
• 2 & - 3 & 3
• \end{array} \right]\]
• E)​ \[7 \left[ \begin{array} { c c c }
• 1 & 1 & 1 \\
• - 3 & 0 & - 1 \\
• 3 & - 3 & 2
• \end{array} \right]\]

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