3 and 4 .Determinants and Matrices
easy

The value of a for which the matrix $A = \left( {\begin{array}{*{20}{c}}a&2\\2&4\end{array}} \right)$is singular if

A

$a \ne 1$

B

$a = 1$

C

$a = 0$

D

$a = - 1$

Solution

(b) Put $a = 1$; $\therefore $ $|A| = \left| {\,\begin{array}{*{20}{c}}1&2\\2&4\end{array}\,} \right| = 4 – 4 = 0$
Hence, $A$ is a singular matrix for $a = 1.$

Standard 12
Mathematics

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