Can a Matrix A² ever equal -I₃ in M₃(ℝ)?

In summary, a matrix is an array of numbers or variables arranged in rows and columns. A matrix property proof is a mathematical demonstration of a property that holds true for all matrices. Some common matrix properties include associativity, commutativity, distributivity, and the existence of an identity element. These proofs are used in scientific research to provide a foundation for mathematical models and validate experimental results. Strategies for proving matrix properties include algebraic manipulations, induction, and counterexamples, as well as careful definition of terms and assumptions.
  • #1
AllRelative
42
2

Homework Statement


Show that no matrix A ∈ M3 (ℝ) exists so that A2 = -I3

Homework Equations

The Attempt at a Solution


This is from a french textbook of first year linear algebra. I'm quite familiar with properties of matrices but I don't have any idea of how to prove this.

Thanks for the help!
 
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  • #2
Think about the determinants in the given equation.
 
  • #3
Compute the determinant of ##A##.
 
  • #4
I took me a while but I got it. Thanks both of you!
 

Related to Can a Matrix A² ever equal -I₃ in M₃(ℝ)?

1. What is a matrix?

A matrix is a rectangular array of numbers or variables arranged in rows and columns.

2. What is a matrix property proof?

A matrix property proof is a mathematical demonstration that a certain property holds true for all matrices, regardless of their size or contents.

3. What are some common matrix properties?

Some common matrix properties include associativity, commutativity, distributivity, and the existence of an identity element.

4. How are matrix property proofs used in scientific research?

Matrix property proofs are used in scientific research to provide a foundation for mathematical models and to demonstrate the validity of experimental results.

5. What are some strategies for proving matrix properties?

Some strategies for proving matrix properties include using algebraic manipulations, induction, and counterexamples. It is also important to carefully define the terms and assumptions of the property being proven.

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