Question

Regra de cramer x+y=5 x-y=1

Answer 1

$\left \{ {{x + y=5} \atop {x - y=1}} \right.$

$D = \left[\begin{array}{ccc}1&1\\1&-1\end{array}\right]$

$D = 1*(-1) - 1*1$
$D = - 1 - 1$
$D = - 2$



$Dx = det \left[\begin{array}{ccc}5&1\\1&-1\end{array}\right]$

$Dx = 5*(- 1) - 1*1$
$Dx = - 5 - 1$
$Dx = - 6$



$Dy = det \left[\begin{array}{ccc}1&5\\1&1\end{array}\right]$

$Dy = 1*1 - 5*1$
$Dy = 1 - 5$
$Dy = - 4$
______________________________

$x = Dx / D$
$x = (- 6) / (- 2)$
$x = 3$

$y = Dy / D$
$y = (- 4) / (- 2)$
$y = 2$

$S = (3,2)$

Answer 2

• x+y = 5
• x-y = 1
+_________
2x = 6
x= 3

3+y = 5
y=2

;D