Question

GENTE ME AJUDEM AINDA HOJE PF!!

Answer 1

$x\:.\:I=x.\left[\begin{array}{ccc}1&0\\\\0&1\end{array}\right] =\left[\begin{array}{ccc}x&0\\\\0&x\end{array}\right]$

$A-x\:.\:I=\left[\begin{array}{ccc}1&3\\\\2&4\end{array}\right]-\left[\begin{array}{ccc}x&0\\\\0&x\end{array}\right]=\left[\begin{array}{ccc}1-x&3\\\\2&4-x\end{array}\right]$

$det\:(A-x.I)=\left|\begin{array}{ccc}1-x&3\\\\2&4-x\end{array}\right|$

$\left|\begin{array}{ccc}1-x&3\\\\2&4-x\end{array}\right|=0$

$(1-x).(4-x)-2\:.\:3=0$

$4-x-4x+x^{2} -6=0$

    $x^{2} -5x-2=0$

   $a=1$

   $b=-5$

   $c=-2$

   $S=x'+x''=-\frac{b}{a} =-\frac{(-5)}{1} =+5$

  $Resposta:5$