Question

Quem pode me ajudar com essa matriz ?

Answer 1

Pela regra de Sarrus temos:

$\left|\begin{array}{ccc}2&4&1\\2&4&x\\3&1&2\end{array}\right| \left\begin{array}{ccc}2&4\\2&4\\3&1\end{array}\right \\\\\\ det = (16+12x+2)-(12+2x+16)\\\\det = 16+12x+2-12-2x-16\\\\det = 10x-10\\\\0 = 10x-10\\\\\boxed{\boxed{x = 1 }}$

Espero ter ajudado. :))