Prove that the set of all algebraic numbers is a countable set. (SOLUTION INCLUDED.):
http://www.tiikoni.com/tis/view/?id=e3a6f8a

I'm stuck at the part of the solution that says P = |a_0| + |a_1| + . . . + |a_n| + n.

Could someone please explain to me what is going on there?

Question

Prove that the set of all algebraic numbers is a countable set. (SOLUTION INCLUDED.):
http://www.tiikoni.com/tis/view/?id=e3a6f8a

I'm stuck at the part of the solution that says P = |a_0| + |a_1| + . . . + |a_n| + n.

Could someone please explain to me what is going on there?

anonymous · Answer

try it with $n=1$ and with $n=2$ that might be enlightening
i have not seen this proof before, usually you just say countable times countable is countable

s3a · Answer

My problem is not just with the computation; I have no idea what P even represents.

I'm assuming the letter P was chosen because it's the first letter of the word "polynomial", but then why is the equation different than that of the equation above it that equals zero?