Question #9a21e

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Answer 1 · 2016-08-07T15:14:17

$x=2, y=-1, z=1$

let $x+2y-4z = -4$ be equation 1
let $2x+5y-9z =-10$ be eq. 2
let $3x-2y+3z = 11$ be eq.3

eq.1 x 2
$2x+4y-8z = -8$ (eq.4)

eq.2 - eq.4
$y-z=-2$ (eq.5)

eq.1 x 3
$3x+6y-12z=-12$ (eq.6)

eq.6-eq3
$8y-15z=-23$ (eq.7)

eq.5 x 8
$8y-8z=-16$ (eq.8)

eq.7 - eq.8
$-7z=-7$
$:. z=1$

sub $z=1$ into eq.5
$y-1=-2$
$:. y=-1$

sub $z=1 and y=-1$ into eq.1
$x-2-4=-4$
$:. x=2$