Question

Which set does not contain an irrational number?

Answer 1

the first 1 {-2.5 .200. 1.23456789 .etc}

Answer 2

On a question like this, immediately look for pi and square roots.

All answers have one of those.

Then look at the square roots. Are there any square roots that clean up nicely, like sqrt(9) or sqrt(16) would? If so, that’s not really an irrational number, because it cleans up to a rational value.

Which answer has that?