8. Let \( L: \mathbf{R}^n \to \mathbf{R}^n \) be a linear transformation. If \( L(\mathbf{x}1) = L(\mathbf{x}2) \), then \( \mathbf{x}1 = \mathbf{x}2 \).
8. Let \( L: \mathbf{R}^n \to \mathbf{R}^n \) be a linear transformation. If \( L(\mathbf{x}1) = L(\mathbf{x}2) \), then \( \mathbf{x}1 = \mathbf{x}2 \).