Explicação passo a passo:
[tex]\left[\begin{array}{ccc}-2&-{1/2}\\7&\sqrt{3}\\3/4&-3\end{array}\right] =\left[\begin{array}{ccc}a_{11{&a_{12}\\a_{21}&a_{22}\\a_{31}&a_{32}\end{array}\right][/tex]
[tex](a_{22})^2-5(a_{12}+a_{31})+a_{32}=\\ \\ (\sqrt{3} )^2-5(-{1\over2}+{3\over4})+(-3)=\\ \\ 3-5({-2+3\over4})-3=\\ \\ \not3-\not3-5({1\over4})=\\ \\\boxed{ -{5\over4}}[/tex]
