Question

Use row operations on augmented matrices to solve the given systems of linear equations.

x + y − z = 0
x + 2y + 4z = −3
3x − y − 22z = 19

Answer 1

1 1 -1 0
1 2 4 -3
3 -1 -22 19

1 1 -1 0
0 1 5 -3 --- I did #2 - #1
0 -4 -19 19 -- I took #3 - 4x#2

1 1 -1 0
0 1 5 -3
0 0 1 7 --- I took #3 - 3x#2

so z = 7
in #2: y + 35 = -3
y = -38

in #1
x - 38 - 7 = 0
x = 45

x=45 , y=-38 , z=7