Question:medium

If $A=\begin{bmatrix}2 & -1\\ -1 & 3\end{bmatrix}$, then the inverse of $(2A^{2}+5A)$ is

Show Hint

Logic Tip: The Cayley-Hamilton theorem states that a matrix satisfies its own characteristic equation. $|A - \lambda I| = \lambda^2 - 5\lambda + 5 = 0 \implies A^2 - 5A + 5I = 0$. You can sometimes use this to reduce matrix polynomials ($A^2 = 5A - 5I$) before computing, trading matrix multiplication for simple addition.
Updated On: Apr 28, 2026
  • $\frac{1}{95}\begin{bmatrix}7 & 3\\ 3 & 4\end{bmatrix}$
  • $\frac{1}{95}\begin{bmatrix}-7 & 3\\ 3 & -4\end{bmatrix}$
  • $\frac{1}{95}\begin{bmatrix}-7 & -3\\ 3 & 4\end{bmatrix}$
  • $\frac{1}{95}\begin{bmatrix}4 & 3\\3 & 7\end{bmatrix}$
Show Solution

The Correct Option is A

Solution and Explanation

Was this answer helpful?
0