Let $x,c$ two cardinals, such that:
$1\lt x \le c$
$c^2 = c$
Prove:
$x^c = 2^c$
So, from the second statement, we know $c$ is infinite, because it cannot be true for a finite cardinal.
I know the "tools" to prove it must be:
- CBS theorem
- cardinals arithmatic
- squeezing theorem
I tried playing with these, but all I got is bunch of inequalities didn't lead to the answer.
EDIT:
What I did so far:
$$\begin{array}{l}x \le b\\{2^x} \le {2^b}\\{\left( {{2^x}} \right)^b} \le {\left( {{2^b}} \right)^b}\\{2^{xb}} \le {2^{bb}}\end{array}$$
I'm pretty much stuck at this point.
HINT: Remember the laws of exponentiation:
To the edit:
HINT: Show that if $x\leq c=c^2\implies xc=c$.