Originally Posted by

**gatordeb** Help, I'm drowning!! In proofs. I am sooooo lost in this class.

Questions:

1. Prove that the set of positive real numbers has cardinal number c. (Hint: try the map x --> e^x.

2. Prove that the open unit interval 9the set of all real x with 0 < x < 1) has cardinal number c. (Hint: Use ex. 1 and the map x --> x/(1 + x), defined on all positive real numbers).

3. Whatis the cardinal number of the closed unit interval (all x with 0 __<__ x __<__ 1)? Of the half open interval (all xx with0 __<__ x < 1)?