Question

which of the following are empty sets .
1. x={x:x is a real no. neither rational nor irrational}
2.y={x:x is a real no. less than itself}
3.Z={x:x is a non-zero real satisfying x+a=0 for every real a}
4.T={x:x a=a for every real a}
5. w={x:x is a point common two skew lines}​

Answer 1

Answer:

1. Empty set (because Real numbers are either rational or irrational)

2. Empty (because every number is equal to itself but not less than itself)

3. {x = -a} Non empty set

4. Non empty set (every number is equals itself)

5. Empty set (no common point for skew lines)