Find the cofactor matrix c and multiply a times cᵗ. compare acᵗ with a⁻¹:
a = [[2, - 1, 0], [- 1, 2, - 1], [0, - 1, 2]]
a⁻¹ = 1/4 * [[3, 2, 1], [2, 4, 2], [1, 2, 3]]
a = [[2, - 1, 0], [- 1, 2, - 1], [0, - 1, 2]]
a⁻¹ = 1/4 * [[3, 2, 1], [2, 4, 2], [1, 2, 3]]