Let A = .
If u1 and u2 are column matrices such that Au1= and Au2= ,
then u1+u2 is equal to
⎡⎢⎣−110⎤⎥⎦
⎡⎢⎣−11−1⎤⎥⎦
⎡⎢⎣−1−10⎤⎥⎦
⎡⎢⎣1−1−1⎤⎥⎦