7 State whether the following statements are true or false; if false, provide a counterexample.
- If \(a\) is rational and \(b\) is rational, then \(a + b\) is rational.
- If \(a\) is rational and \(b\) is irrational, then \(a + b\) is irrational.
- If \(a\) is irrational and \(b\) is irrational, then \(a + b\) is irrational.