Prove or find a counterexample: For all real numbers x and y it holds that x + y is irrational if, and only if, both x and y are irrational.
Can anyone give me a hint just about how to start cause i cannot come up on how and where to start.
Do I have to look for 2 irrational numbers and add then , iff, both have to be irrational and how do i come up with a counterexample or a prove? i need help