Question

If A = $\left[\begin{array}{ccc}-1&2&3\\2&5&6\\3&x&7\end{array}\right]$ is a symmetric matrix, then find x.

Answer 1

Answer:

x=6

Step-by-step explanation:

$A =\left[\begin{array}{ccc}-1&2&3\\2&5&6\\3&x&7\end{array}\right]$  

if A is a symmetric matrix then

$A =A^{T}\\\\\\ \left[\begin{array}{ccc}-1&2&3\\2&5&6\\3&x&7\end{array}\right] =\left[\begin{array}{ccc}-1&2&3\\2&5&x\\3&6&7\end{array}\right]$

to find x ,just compare respective element in both matrices

so

x=6