Question

SISTEMA ESCALONADO:

x + y +z = 3
-2 + y - z = 0
3x - y - z = - 7

Answer 1

$\left \{ {{x+y+z=3(I)} \atop {-2+y-z=0(II)}} \atop {3x-y-z=-7(III)}} \right.$

$+ \left \{ {{x+y+z=3(I)} \atop {3x-y-z=-7(III)}} \right.$
$4x=-4$
$x= \frac{-4}{4}$
$x=-1$

$x+y+z=3$
$-1+y+z=3$
$y+z=3+1$
$y+z=4$

$-2+y-z=0$
$y-z=2$

$+ \left \{ {{y+z=4} \atop {y-z=2}} \right.$
$2y=6$
$y= \frac{6}{2}$
$y=3$

$x+y+z=3$
$-1+3+z=3$
$2+z=3$
$z=3-2$
$z=1$