Cayley–Hamilton matrix identity
For a finite square matrix A over a field, its characteristic polynomial p(t)=det(tI−A)=tⁿ+cₙ₋₁tⁿ⁻¹+⋯+c₀ satisfies p(A)=Aⁿ+cₙ₋₁Aⁿ⁻¹+⋯+c₀I=0.
Key knowledge
For a finite square matrix A over a field, its characteristic polynomial p(t)=det(tI−A)=tⁿ+cₙ₋₁tⁿ⁻¹+⋯+c₀ satisfies p(A)=Aⁿ+cₙ₋₁Aⁿ⁻¹+⋯+c₀I=0. Polynomial division by p reduces any polynomial in A to degree below n; when c₀≠0 the identity also expresses A⁻¹ as a polynomial in A.
Values and equations
Aⁿ+cₙ₋₁Aⁿ⁻¹+⋯+c₁A+c₀I=0
- A
- n×n matrix over one field
- cᵢ
- Coefficients of det(tI−A)
- I
- Identity matrix of the same size
Conditions and scope
- n≥1; substitute A into the already expanded scalar polynomial, with constant coefficient multiplying I.
- The theorem applies to defective matrices too; it does not state diagonalizability. The monic convention differs by a sign factor from det(A−tI).
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Theorem 6.2, expanded polynomial definition and Example 6.5 powers/inverse use. The source explicitly omits the theorem proof; general polynomial reduction follows from Euclidean division and p(A)=0.
2026-10-10 · Independent AI editorial review: All241 compact claims, hypotheses, displayed equations/conventions and all596 origin semantic links read; entire241-entry author exact-source inspection matrix and declared limitations reviewed. Prior105 actual inherited Mathematics/Information records read for whole-inventory breadth. Targeted independent primary sections are listed below; this does NOT claim every cited source body or every proof was independently re-read. This is AI reference-content review, not human disciplinary certification, exhaustive textbook reproduction or experimental replication. Receipt: mathematics-information-independent-content-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- math-cayley-hamilton
- Revision
- university-core.1
- Structured reference record
- University core expansion