Linear Algebra and Its Applications (5th Edition)

Published by Pearson
ISBN 10: 032198238X
ISBN 13: 978-0-32198-238-4

Chapter 2 - Matrix Algebra - 2.8 Exercises - Page 153: 19

Answer

See explanation

Work Step by Step

Suppose$A=\left[\begin{array}{lll}.4 & .2 & .3 \\ .3 & .6 & .3 \\ .3 & .2 & .4\end{array}\right]$. Then $A^{2}=\left[\begin{array}{lll}.31 & .26 & .30 \\ .39 & .48 & .39 \\ .30 & .26 & .31\end{array}\right]$ Instead of computing $A^{3}$ next, speed up the calculations by computing \[ \begin{array}{l} A^{4}=A^{2} A^{2}=\left[\begin{array}{ccc} .2875 & .2834 & .2874 \\ .4251 & .4332 & .4251 \\ .2874 & .2834 & .2875 \end{array}\right] \\ A^{8}=A^{4} A^{4}=\left[\begin{array}{ccc} .2857 & .2857 & .2857 \\ .4285 & .4286 & .4285 \\ .2857 & .2857 & .2857 \end{array}\right] \\ & \\ & \\ & \end{array} \] To four decimal places, as k increases, $A^{k}=\left[\begin{array}{ccc}.2857 & .2857 . & .28577 \\ .4286 & .4286 & .4286 \\ .2857 & .2857 & .2857\end{array}\right]$ rational format $A^{k}=\left[\begin{array}{ccc}2 / 7 & 2 / 7 & 2 / 7 \\ 3 / 7 & 3 / 7 & 3 / 7 \\ 2 / 7 & 2 / 7 & 2 / 7\end{array}\right]$ \[ \begin{array}{l} \text { If } B=\left[\begin{array}{rrr} 0 & .2 & .3 \\ .1 & .6 & .3 \\ .9 & .2 & .4 \end{array}\right] \\ B^{2}=\left[\begin{array}{rrr} .29 & .18 & .18 \\ .33 & .44 & .33 \\ .38 & .38 & .49 \end{array}\right] \end{array} \] $B^{4}=\left[\begin{array}{ccc}.2119 & .1998 & .1998 \\ .3663 & .3764 & .3663 \\ .4218 & .4218 & .4339\end{array}\right]$ $B^{8}=\left[\begin{array}{ccc}.2024 & .2022 & .2022 \\ .3707 & .3709 & .3707 \\ .4269 & .4269 & .4271\end{array}\right]$ Or in rational format, $B^{k}=\left[\begin{array}{ccc}18 / 89 & 18 / 89 & 18 / 89 \\ 33 / 89 & 33 / 89 & 33 / 89 \\ 38 / 89 & 38 / 89 & 38 / 89\end{array}\right]$
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