for a vector v, let r be the reflection of v over the line \(x = t \begin{pmatrix} 2 \\ -1 \end{pmatrix}\). There exists a 2 X 2 matrix R such that r = Rv for all2-dimensional vectors v. Find R.
The matrix is \(\begin{pmatrix} 1 & 2 \\ -2 & 4 \end{pmatrix}\)
