# How do you solve using gaussian elimination or gauss-jordan elimination, x+3y-6z=7, 2x-y+2z=0, x+y+2z=-1?

Jan 18, 2016

$x = 1$
$y = 0$
$z = - 1$

#### Explanation:

Initial Augmented Matrix:
[ ( 1.00, 3.00, -6.00, 7.00), ( 2.00, -1.00, 2.00, 0.00), ( 1.00, 1.00, 2.00, -1.00) ]

Pivot Action $n$
pivot row = n; pivot column = n; pivot entry augmented matrix entry at (n,n)

$$1. convert pivot n row so pivot entry = 1
2. adjust non-pivot rows so entries in pivot column = 0


Pivot $\textcolor{b l a c k}{1}$
Pivot Row 1 reduced by dividing all entries by 1.00 so pivot entry = 1
[ ( 1.00, 3.00, -6.00, 7.00), ( 2.00, -1.00, 2.00, 0.00), ( 1.00, 1.00, 2.00, -1.00) ]

$$Non-pivot rows reduced for pivot column
by subtracting appropriate multiple of pivot row 1 from each non-pivot row


[ ( 1.00, 3.00, -6.00, 7.00), ( 0.00, -7.00, 14.00, -14.00), ( 0.00, -2.00, 8.00, -8.00) ]

Pivot $\textcolor{b l a c k}{2}$
Pivot Row 2 reduced by dividing all entries by -7.00 so pivot entry = 1
[ ( 1.00, 3.00, -6.00, 7.00), ( 0.00, 1.00, -2.00, 2.00), ( 0.00, -2.00, 8.00, -8.00) ]

$$Non-pivot rows reduced for pivot column
by subtracting appropriate multiple of pivot row 2 from each non-pivot row


[ ( 1.00, 0.00, 0.00, 1.00), ( 0.00, 1.00, -2.00, 2.00), ( 0.00, 0.00, 4.00, -4.00) ]

Pivot $\textcolor{b l a c k}{3}$
Pivot Row 3 reduced by dividing all entries by 4.00 so pivot entry = 1
[ ( 1.00, 0.00, 0.00, 1.00), ( 0.00, 1.00, -2.00, 2.00), ( 0.00, 0.00, 1.00, -1.00) ]

$$Non-pivot rows reduced for pivot column
by subtracting appropriate multiple of pivot row 3 from each non-pivot row


[ ( 1.00, 0.00, 0.00, 1.00), ( 0.00, 1.00, 0.00, 0.00), ( 0.00, 0.00, 1.00, -1.00) ]