Chapter 8: Problem 71
Describe how to perform scalar multiplication. Provide an example with your description.
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These are the key concepts you need to understand to accurately answer the question.
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Chapter 8: Problem 71
Describe how to perform scalar multiplication. Provide an example with your description.
These are the key concepts you need to understand to accurately answer the question.
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Find \(A^{-1}\) by forming \([A | I]\) and then using row operations to obtain \([I | B],\) where \(A^{-1}=[B] .\) Check that \(A A^{-1}=I\) and \(A^{-1} A=I\) $$A=\left[\begin{array}{rrr} 1 & -1 & 1 \\ 0 & 2 & -1 \\ 2 & 3 & 0 \end{array}\right]$$
Use the coding matrix $$\begin{aligned}&A=\left[\begin{array}{rrr}1 & -1 & 0 \\\3 & 0 & 2 \\ -1 & 0 & -1\end{array}\right] \text { and its inverse }\\\&A^{-1}=\left[\begin{array}{rrr} 0 & 1 & 2 \\\\-1 & 1 & 2 \\\0 & -1 & -3\end{array}\right] \text { to write a cryptogram for each } \end{aligned}$$ message. Check your result by decoding the cryptogram. $$\begin{aligned}&\begin{array}{ccccccccc}\mathrm{S} & \mathrm{T} & \mathrm{A} & \mathrm{Y} & _- & \mathrm{W} & \mathrm{E} & \mathrm{L} & \mathrm{L} \\ 19 & 20 & 1 & 25 & 0 & 23 & 5 & 12 & 12\end{array}\\\&\text { Use }\left[\begin{array}{rrr} 19 & 25 & 5 \\\20 & 0 & 12 \\\1 & 23 & 12\end{array}\right]\end{aligned}$$
It's January \(1,\) and you've written down your major goal for the year. You do not want those closest to you to see what you've written in case you do not accomplish your objective. Consequently, you decide to use a coding matrix to encode your goal. Explain how this can be accomplished.
Explain how to write a linear system of three equations in three variables as a matrix equation.
Use a graphing utility to find the multiplicative inverse of each matrix. Check that the displayed inverse is correct. $$\left[\begin{array}{rrrr}7 & -3 & 0 & 2 \\\\-2 & 1 & 0 & -1 \\ 4 & 0 & 1 & -2 \\\\-1 & 1 & 0 & -1\end{array}\right]$$
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