Linear Algebra and Its Applications (5th Edition)

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

Chapter 2 - Matrix Algebra - 2.2 Exercises - Page 111: 3

Answer

I will type matrices like this: (a b c/d e f), where (a b c) is the first row and (d e f) is the second row. Answer: (1 1/$\frac{-7}{5}$ $\frac{-8}{5}$)

Work Step by Step

I will type matrices like this: (a b c/d e f), where (a b c) is the first row and (d e f) is the second row. This is a 2x2 matrix, therefore let A = (a b/ c d) if ad-bc ≠ 0. Thus, $A^{-1}$ = $\frac{1}{ad-bc}$ × (d -b/-c a) ad-bc = 8×(-5) - (-7)×5. Thus, ad-bc = -5 $A^{-1}$ = $\frac{-1}{5}$ × (-5 -5/7 8) which is (1 1/$\frac{-7}{5}$ $\frac{-8}{5}$)
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