## Linear Algebra: A Modern Introduction

We know that if the determinant of a matrix $\begin{bmatrix} a &b \\ c & d \end{bmatrix}$ $, D=ad-bc$ is $0$, then the matrix is not invertible. Here $D=3.55\cdot0.6-0.25\cdot8.52=2.13-2.13=0$, thus the matrix is not invertible.