Solve the system of equations using:
The matrix inverse. define the resulting vector for as xinv
Matlab's built-in solvers mldivide, define the resulting vector as xmat
8x₁ + 2x₂ - 2x₃ = - 2
10x₁ + 2x₂ + 4x₃ = 4
12x₁ + 2x₂ + 2x₃ = 6