Resposta:
[tex]a:\ x=4\\\\c:\ x=7[/tex]
Explicação passo a passo:
[tex]2-\\\\a)\ \left[\begin{array}{ccc}3&2&x\\1&-2&x\\2&-1&x\end{array}\right]\left\begin{array}{ccc}3&2\\1&-2\\2&-1\end{array}\right]=8\\\\\\3\times-2\times{x}+2\times{x}\times2+x\times1\times-1-[2\times1\times{x}]-[3\times{x}\times-1]-[x\times-2\times2]=8\\\\\\-6x+4x-x-2x+3x+4x=8\\\\\\2x=8\\\\\\x=\frac{8}{2}=4[/tex]
[tex]c)\ \left[\begin{array}{ccc}2&3&0\\8&2&1\\-1&x&2\end{array}\right]\left\begin{array}{ccc}2&3\\8&2\\-1&x\end{array}\right]=-61\\\\\\2\times2\times2+3\times1\times-1+0\times8\times{x}-[3\times8\times2]-[2\times1\times{x}]-[0\times2\times-1]=-61\\\\\\4-3+0-48-2x-0=-61\\\\\\-2x=-61-4+3+48\\\\\\-2x=-65+51\\\\\\-2x=-14\\\\\\2x=14\\\\\\x=\frac{14}{2}=7[/tex]
