Is the x in set A the same as the x in set C? _ High School Mathematics Highlights
(1), {x|x=0} means {0}.
(2) It means that the solution of the equation in different {x | x 2-ax-1= 0} has two real roots.
The latter refers to the range that A meets the requirements. A can be any number. If we look at it by discriminant, everything A takes has real roots.