To prove that the sum \( t = r + s \) is irrational if \( r \) is rational and \( s \) is rational, the steps should be arranged in a logical sequence. The correct sequence is:
- Step 2: For a contradiction, assume that \( t \) is rational, and write \( r \) and \( t \) as fractions.
- Step 4: Find a common denominator.
- Step 1: Subtract, writing \( s \) as a fraction.
- Step 3: Realize a contradiction.
So the correct order is:
Step 2, Step 4, Step 1, Step 3