If  show that  A–1 = A. from Mathematics Determinants

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 Multiple Choice QuestionsLong Answer Type

191.

If straight A space equals open square brackets table row 2 cell space space space space space space space 3 end cell row 1 cell space space minus 4 end cell end table close square brackets comma space straight B space equals space open square brackets table row cell space space space 1 end cell cell space space space space minus 2 end cell row cell negative 1 end cell cell space space space space space space 3 end cell end table close square brackets comma
verify that (AB)–1 = B–1 A–1

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192.

Let straight A space equals space open square brackets table row 3 cell space space space 7 end cell row 2 cell space space 5 end cell end table close square brackets space and space straight B space equals space open square brackets table row 6 cell space space 8 end cell row 7 cell space space 9 end cell end table close square brackets comma verify that (AB)–1 = B–1 A–1.

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193. Verify that (AB)–1 = B–1 A–1 for the matrices A and B where straight A space equals space open square brackets table row 3 cell space space 2 end cell row 7 cell space space 5 end cell end table close square brackets comma space space straight B space equals space open square brackets table row 4 cell space space 6 end cell row 3 cell space space 2 end cell end table close square brackets
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194. Verify that (AB)–1 = B–1 A–1 for the matrices A and B where straight A space equals open square brackets table row 3 cell space space 2 end cell row 7 cell space space 5 end cell end table close square brackets comma space space straight B space equals space open square brackets table row 6 cell space space space space 7 end cell row 8 cell space space space space 9 end cell end table close square brackets.

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195. Verify that (AB)–1 = B–1 A–1 for the matrices A and B where straight A space equals space open square brackets table row 2 cell space space space 1 end cell row 5 cell space space space 3 end cell end table close square brackets comma space space space straight B space equals space open square brackets table row 4 cell space space space 5 end cell row 3 cell space space 4 end cell end table close square brackets.

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 Multiple Choice QuestionsShort Answer Type

196.

Find (AB)–1 if straight A space equals space open square brackets table row 3 cell space 4 end cell row 1 cell space 1 end cell end table close square brackets comma space space straight B to the power of negative 1 end exponent space equals space open square brackets table row 4 cell space space 3 end cell row 2 cell space space 1 end cell end table close square brackets

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197.

Find (AB)–1 if straight A space equals space open square brackets table row 5 cell space space 0 end cell row 2 cell space space space 3 end cell end table close square brackets comma space space space straight B to the power of negative 1 end exponent space equals space open square brackets table row 1 cell space space space 2 end cell row 1 cell space space 4 end cell end table close square brackets

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 Multiple Choice QuestionsLong Answer Type

198.

Find the inverse of the matrix
straight A space equals space open square brackets table row cell negative 1 end cell cell space space 1 end cell cell space space 2 end cell row cell space space space 3 end cell cell negative 1 end cell cell space space 1 space end cell row cell space minus 1 end cell cell space space 3 end cell cell space 4 end cell end table close square brackets.

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199. Find the inverse of the matrix:
open square brackets table row 1 cell space space space minus 1 end cell cell space space space space space space 2 end cell row 0 cell space space space space space space 2 end cell cell space space space minus 3 end cell row 3 cell space space space minus 2 end cell cell space space space space space space 4 end cell end table close square brackets.
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200.

If straight A space equals space open square brackets table row 0 cell space space space 0 end cell cell space space 1 end cell row 0 cell space space 1 end cell cell space space 0 end cell row 1 cell space space 0 end cell cell space space 0 end cell end table close square brackets comma show that  A–1 = A.


straight A space equals space open square brackets table row 0 cell space space space 0 end cell cell space space space 1 end cell row 0 cell space space space 1 end cell cell space space space space 0 end cell row 0 cell space space space space 0 end cell cell space space space space 1 end cell end table close square brackets
therefore space space space open vertical bar straight A close vertical bar space equals space open vertical bar table row 0 cell space space space 0 end cell cell space space space space 1 end cell row 0 cell space space 1 end cell cell space space space 0 end cell row 1 cell space space space 0 end cell cell space space space 0 end cell end table close vertical bar space equals 1 open vertical bar table row 0 cell space space space 1 end cell row 1 cell space space space 0 end cell end table close vertical bar space equals space 1 left parenthesis 0 minus 1 right parenthesis space equals space minus 1 not equal to space space 0 space space space space rightwards double arrow space space straight A to the power of negative 1 end exponent space exists. space
Co-factors of the elements of the first row of | A | are
 open vertical bar table row 1 cell space space 0 end cell row 0 cell space 0 end cell end table close vertical bar comma space space minus open vertical bar table row 0 cell space space space space 0 end cell row 1 cell space space space space 0 end cell end table close vertical bar comma space space open vertical bar table row 0 cell space space space 1 end cell row 1 cell space space 0 end cell end table close vertical bar

i.e. 0, 0, – 1 respectively
Co-factors of the elements of the second row of | A | are
negative open vertical bar table row 0 cell space space 1 end cell row 0 cell space space 0 end cell end table close vertical bar comma space space open vertical bar table row 0 cell space space space 1 end cell row 1 cell space space space 0 end cell end table close vertical bar comma space space minus open vertical bar table row 0 cell space space 0 end cell row 1 cell space space 0 end cell end table close vertical bar
i.e. 0,–1, 0, respectively.
Co-factors of the elements of the third row of | A | are
open vertical bar table row 0 cell space space 1 end cell row 1 cell space 0 end cell end table close vertical bar comma space space minus open vertical bar table row 0 cell space space space space 1 end cell row 0 cell space space space space 0 end cell end table close vertical bar comma space space open vertical bar table row 0 cell space space space 0 end cell row 0 cell space space 1 end cell end table close vertical bar
i.e., – 1, 0, 0 respectively.
therefore space space space adj. space straight A space equals space open square brackets table row 0 cell space space 0 end cell cell space space space minus 1 end cell row 0 cell space minus 1 end cell cell space space space space space space 0 end cell row cell negative 1 end cell cell space space 0 end cell cell space space space space space space 0 end cell end table close square brackets to the power of apostrophe space equals space space open square brackets table row cell space 0 end cell cell space space space space 0 end cell cell space space space minus 1 end cell row cell space space 0 end cell cell space space minus 1 end cell cell space space space space space 0 end cell row cell negative 1 end cell cell space space space space 0 end cell cell space space space space 0 end cell end table close square brackets
Now space straight A to the power of negative 1 end exponent space equals space fraction numerator adj. space straight A over denominator open vertical bar straight A close vertical bar end fraction space equals space fraction numerator 1 over denominator negative 1 end fraction open square brackets table row 0 cell space space space space 0 end cell cell space space space minus 1 end cell row 0 cell space space minus 1 end cell cell space space space space space 0 end cell row cell negative 1 end cell cell space space space space 0 end cell cell space space space space 0 end cell end table close square brackets space equals space open square brackets table row 0 cell space space 0 end cell cell space space 1 end cell row 0 cell space space 1 end cell cell space space 0 end cell row 1 cell space space 0 end cell cell space space 0 end cell end table close square brackets space equals space straight A
therefore space space space straight A to the power of negative 1 end exponent space equals space straight A.




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