I'd like to know if I did these problems correctly:

1.Give an example of a partition of N into 3 subsets.

ANSWER: Let s={A,B,C) where A={x ∈ N:2x},B={x ∈ N:4x-1} and C={1}

2.For a real # r, define S<subscript>r</subscript>to be the interval [r-1,r+2]. Let A={1,3,4}. Determine ∪∝∈A S∝ and ∩∝∈ A S∝

ANSWER: ∪∝∈A S∝=(-∞,∞) and ∩∝∈ A S∝=0(empty set)

I'm not sure how to answer this next problem, I'm sure if I see part "a" done I can do the other parts that I didn't post!

3.For a real number r, define A<subscript>r</subscript>={r^2} B<subscript>r</subscript> as the closed interval[r-1,r+1] and C<subscript>r</subscript> as the interval (r,∞) For S={1,2,4}

a) ∪∝∈S A∝ and ∩∝∈ S A∝ btw this is part of the problem not the answer >_>