Answer:
x₁ = 179 , x₂ = 17 , x₃ = - 3
Explanation:
x₁ - 9x₂ + 7x₃ = 5 → (1)
x₂ + 7x₃ = - 4 → (2)
x₃ = - 3
substitute x₃ = - 3 into (2) and solve for x₂
x₂ + 7(- 3) = - 4
x₂ - 21 = - 4 ( add 21 to both sides )
x₂ = 17
substitute x₂ = 17 and x₃ = - 3 into (1) and solve for x₁
x₁ - 9(17) + 7(- 3) = 5
x₁ - 153 - 21 = 5
x₁ - 174 = 5 ( add 174 to both sides )
x₁ = 179
solution is x₁ = 179 , x₂ = 17 , x₃ = - 3