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Matrices & Determinants (Advanced)

Harder items at competition-adjacent depth.

Phase 2 · JEE

Matrices & Determinants: core idea

Inverse 2×2.

Example problem: hint and answer

Eigenvalues of (0110)\begin{pmatrix}0&1\\1&0\end{pmatrix}: larger?

Hint: Solve. Answer: 1.

Practice (9 problems — type your answers)

  • 1. Cayley–Hamilton: for A=(1101)A=\begin{pmatrix}1&1\\0&1\end{pmatrix}, A2−2A+IA^2-2A+I equals zero matrix? 1/01/0

  • 2. If AA diagonalizable D=diag(2,3)D=\mathrm{diag}(2,3), A2A^{2} eigenvalues product?

  • 3. Rank of (123246001)\begin{pmatrix}1&2&3\\2&4&6\\0&0&1\end{pmatrix}?

  • 4. Det of (120030004)\begin{pmatrix}1&2&0\\0&3&0\\0&0&4\end{pmatrix}?

  • 5. Nilpotent N≠0N\ne0, N2=0N^2=0 for 2×22\times2: possible det?

  • 6. Minimal polynomial degree of (2002)\begin{pmatrix}2&0\\0&2\end{pmatrix}?

  • 7. Exp of zero matrix: det?

  • 8. System Ax=0Ax=0 nontrivial iff det AA?

  • 9. If eigenvalues 1,2,31,2,3, det AA?

Matrices & Determinants Practice Problems — Advanced