Question

What is "a" if B=is a singular matrix| 22 a​

Answer 1

Answer:

The value of a=4

Step-by-step explanation:

Given the matrix

$B=\begin{pmatrix}1\:&\:2\:\\ \:\:\:2\:&\:a\end{pmatrix}$

• A matrix is singular if its determinent is zero.

so solving the matrix B by taking its determinant to get the value a

$\det \begin{pmatrix}1&2\\ 2&a\end{pmatrix}=0$

as according to determinant formula

$\det \begin{pmatrix}a\:&\:b\:\\ c\:&\:d\:\end{pmatrix}\:=\:ad-bc$

 $1\cdot \:a-2\cdot \:2=0$    

  $a-4=0$

   $a=4$          

Therefore, the value of a=4