# Math Help - Cardinality of a Set

1. ## Cardinality of a Set

Im looking for the cardinality of a Set where X is an element of the Real Numbers such that lxl = -1..... what's this mean ?!

2. HINT: There is no real number such that $|x|=-1$

3. Originally Posted by Plato
HINT: There is no real number such that $|x|=-1$

So, Would it just be the empty Set ?

4. Well, YES.