Welcome to Linear Transformation

Algebra Level 5

Let \(j: \mathbb{R^2} \rightarrow \mathbb{R^2}\) be the linear operator defined by \((x,y) \rightarrow (x + 2y, -y)\). If \(A = Mat_{E}(j)\) where \(E =\){\((1,0),(0,1)\)}. Find \(-|A|\).