5.1.8 Affine transformations

Problem: Find the square of the distance from the point \( A= \) \( (1,0,0,1) \) to the plane given by the system of equations \[ x_{1}-x_{2}-x_{3}+x_{4}=0,2 x_{1}+x_{2}-x_{3}+x_{4}=1 \text {. } \]