Question

ME AJUDEM, É URGENTE!
Equação com determinantes

Answer 1

Espero ter ajudado.

$\begin{pmatrix}1&2&x\\ -1&x&\left(x+1\right)\\ 3&2&x\end{pmatrix}=6\\\\\\1\cdot \det \begin{pmatrix}x&\left(x+1\right)\\ 2&x\end{pmatrix}-2\cdot \det \begin{pmatrix}-1&\left(x+1\right)\\ 3&x\end{pmatrix}+x\det \begin{pmatrix}-1&x\\ 3&2\end{pmatrix}\\\\\\1\cdot \left(x^2-2\left(x+1\right)\right)-2\left(-4x-3\right)+x\left(-2-3x\right)\\\\\\-2x^2+4x+4=6\\\\\boxed{x=1}$