$A^{T}=\left[\begin{array}{rr}
1 & -2 \\
3 & -1
\end{array}\right]$. To show that $\left(A^{T}\right)^{T}=A$, we simply need to show that the transpose of the transpose of $A$ is equal to $A$. That is, $\left(\left(A^{T}\right)^{T}\right)_{ij}=\left(A\right)_{ij}$
Show more…