Let X, Y be two n × n real matrices such that XY = X2 + X + I.
Which of the following statements are necessarily true?
1
X is invertible.
2
X + I is invertible.
3
XY = YX.
4
Y is invertible.
Let X, Y be two n × n real matrices such that XY = X2 + X + I.
Which of the following statements are necessarily true?