To find: - x , y , z

Given set of lines are : -

x + y + z = 4;

2x – y + z = - 1;

2x + y – 3z = - 9.

Converting the following equations in matrix form,

AX = B

R₂ – 2R₁

R₃ –2R₁

3R₃ - R₂

Again converting into equations, we get

X + y + z = 4

- 3y - z = - 9

- 14z = - 42

Z = 3

- 3y - 3 = - 9

- 3y = - 6

Y = 2

X + 2 + 3 = 4

X = 4 - 5

X = - 1

∴