Mathematics · 2021
JEE Main · 27 July 2021, Shift 1 · Q65
Let A = [1, 2; -1, 4]. If A^-1=α I +β A, α, β ∈ R, I is a 2 × 2 identity matrix, then 4(α-β) is equal to:
Let $\displaystyle \mathrm{A}=\left[\begin{array}{rr}1 & 2 \\ -1 & 4\end{array}\right]$. If $\displaystyle \mathrm{A}^{-1}=\alpha \mathrm{I}+\beta \mathrm{A}, \alpha, \beta \in \mathbf{R}$, I is a $\displaystyle 2 \times 2$ identity matrix, then $\displaystyle 4(\alpha-\beta)$ is equal to:
Official answer
(2)
$\displaystyle 4$
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JEE Main 2021 Mathematics question, with the answer from NTA’s final answer key. Where our answers come from.