A determinant is a scalar associated with a square matrix. Its zero or nonzero value signals whether the matrix has an inverse and whether the corresponding linear system can be solved exactly. section 2.12
Use the determinant to interpret a square linear system:
- If det(A) ≠ 0, A⁻¹ exists, paralleling the scalar condition a ≠ 0. section 2.12
- If det(A) = 0, the matrix is singular, its rows or columns are linearly dependent, and the system cannot be solved exactly. section 2.12.1
- A determinant close to zero indicates numerical instability: small input changes can produce drastically different solutions. section 2.12.1
Dependent equations
For x₁ + x₂ = 2 and 2x₁ + 2x₂ = 4, the second equation duplicates the first. The coefficient matrix has determinant 2 × 1 − 1 × 2 = 0, confirming singularity and the absence of an exact unique solution. section 2.12.1
Although determinants and inverses matter conceptually, direct computation is normally delegated to linear-algebra software; explicitly computing matrix inverses is numerically unstable. section 2.12

