Question

Dada a matriz: Imagem a baixo

Answer 1

$C= \left[\begin{array}{ccc}a_{11}&a_{12}\\a_{21}&a_{22}\\a_{31}&a_{32}\\a_{41}&a_{42}\end{array}\right]}\\\\\\ C=\left[\begin{array}{ccc}-2&3\\7&-5\\\frac{1}{2}&-1\\1&2,5\end{array}\right]}\\\\\\ \mathsf{a_{31}=\dfrac{1}{2}}\\\\ \mathsf{a_{42}=2,5=\dfrac{5}{2}}\\\\\\ \mathsf{3a_{31}-5a_{42}=3\cdot\dfrac{1}{2}-5\cdot\dfrac{5}{2}}\\\\\\ \mathsf{3a_{31}-5a_{42}=\dfrac{3}{2}-\dfrac{25}{2}}\\\\\\ \mathsf{3a_{31}-5a_{42}=-\dfrac{22}{2}}\\\\\\ \boxed{\mathsf{3a_{31}-5a_{42}=-11}}$