The question I am working on is:
Use a proof by contradiction to prove that the sum of an irrational number and a rational number is irrational.
After searching through Google, to see if this particular question had been asked before, I found this: http://answers.yahoo.com/question/index?qid=20081012182747AA3AaHz
I am looking exclusively at Charles' answer. I understand the proof, and its steps, I just don't understand how it proves the original statement is true; I only see it as proving that, if you add two rational numbers, you get another rational number. Could someone help me?