## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson

# Chapter 10 - Systems of Equations and Inequalities - Section 10.4 Matrix Algebra - 10.4 Assess Your Understanding - Page 778: 69

#### Answer

$A^{-1}\approx\left[\begin{array}{rrrr} {0.02}&{-0.04}&{-0.01}&{0.01}\\ {-0.02}&{0.05}&{0.03}&{-0.03}\\ {0.02}&{0.01}&{-0.04}&{0.00}\\ {-0.02}&{0.06}&{0.07}&{0.06}\end{array}\right]$

#### Work Step by Step

Our aim is to determine the inverse of the following matrix by using a graphing calculator and round-off to two decimal places. $A=\begin{bmatrix} 44 & 21& 18&6 \\-2& 10 & 15&5 \\ 21&12& -12&4\\-8&-16&4&9 \end{bmatrix}$ Using a graphing calculator (or computer algebra system), we obtain the inverse matrix below: $A^{-1}\approx\left[\begin{array}{rrrr} {0.02}&{-0.04}&{-0.01}&{0.01}\\ {-0.02}&{0.05}&{0.03}&{-0.03}\\ {0.02}&{0.01}&{-0.04}&{0.00}\\ {-0.02}&{0.06}&{0.07}&{0.06}\end{array}\right]$

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