Solve Linear Algebra Questions: Finding Inverses and Determinants"

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SUMMARY

This discussion focuses on solving linear algebra problems involving matrix inverses and determinants. For question 1, the matrix A satisfies the equation 3A² + 6A - I = 0, and the inverse of A can be found by manipulating this equation, specifically by multiplying through by A⁻¹. In question 2, for a 3x3 matrix A where 4A = A⁷, the determinant can be determined using the properties of determinants, leading to the conclusion that det(4A) = 4³ det(A) and det(A⁷) = (det(A))⁷.

PREREQUISITES
  • Understanding of matrix operations and properties
  • Familiarity with determinants and their calculations
  • Knowledge of matrix inverses and their derivation
  • Basic algebraic manipulation skills
NEXT STEPS
  • Study the derivation of matrix inverses using algebraic identities
  • Learn about the properties of determinants, specifically for scalar multiplication
  • Explore the implications of the Cayley-Hamilton theorem on matrix equations
  • Investigate the relationship between eigenvalues and determinants in matrices
USEFUL FOR

Students studying linear algebra, educators teaching matrix theory, and anyone seeking to enhance their problem-solving skills in matrix equations and determinants.

rabihtawil
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Homework Statement



question 1:
If A is a matrix satisfying 3A^2+6A-I=0, find the inverse of A.

question 2:
Let A be a 3x3 matrix with 4A = A^7. Find the possible values det A.

Homework Equations



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The Attempt at a Solution



this was a very long homework about 17 questions, i solved the others but i got no clue where to start with these, any help is appreciated.

Best Regards.
 
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rabihtawil said:
question 1:
If A is a matrix satisfying 3A^2+6A-I=0, find the inverse of A.
HINT: Multiply through by A-1
rabihtawil said:
question 2:
Let A be a 3x3 matrix with 4A = A^7. Find the possible values det A.
HINTs: det(4A) = 4ndet(A) for an nxn matrix. det(A7) = (det(A))7
 
Or, for question 1, note that [itex]3A^2+ 6A= I[/itex] so [itex](3A+ 6)A= I[/itex].
 

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