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Matrices & Determinants (Standard)

Multi-step exam-style items.

Phase 2 · JEE

Matrices & Determinants: core idea

Matrix multiplication.

Example problem: hint and answer

Inverse of (2111)\begin{pmatrix}2&1\\1&1\end{pmatrix}: top-left entry?

Hint: 1det⁡adj\tfrac1{\det}\mathrm{adj}. Answer: 1.

Practice (9 problems — type your answers)

  • 1. Eigenvalues of (2003)\begin{pmatrix}2&0\\0&3\end{pmatrix}: product?

  • 2. Det after row swap of (1234)\begin{pmatrix}1&2\\3&4\end{pmatrix}?

  • 3. Rank of I3I_3?

  • 4. (1101)(1011)\begin{pmatrix}1&1\\0&1\end{pmatrix}\begin{pmatrix}1&0\\1&1\end{pmatrix}: bottom-left?

  • 5. Char poly of (0100)\begin{pmatrix}0&1\\0&0\end{pmatrix}: constant term?

  • 6. Triangular (2304)\begin{pmatrix}2&3\\0&4\end{pmatrix} det?

  • 7. Solve (1101)(xy)=(32)\begin{pmatrix}1&1\\0&1\end{pmatrix}\begin{pmatrix}x\\y\end{pmatrix}=\begin{pmatrix}3\\2\end{pmatrix}: xx?

  • 8. Adjugate of (abcd)\begin{pmatrix}a&b\\c&d\end{pmatrix} top-left?

  • 9. If det A=5A=5, det (2A)(2A) for 2×22\times2?

Matrices & Determinants Practice Problems — Standard