question number 2: I'm confused! isnt "Non-positive numbers and non-negative numbers" = "Negative and positive numbers" ?

Hey Mohamed, Thank you for reaching out! There is a subtle difference between the two. Negative numbers include all numbers strictly smaller than zero. A non-positive number, on the other hand, refers to all number smaller than or equal to zero. Analogously, positive numbers are those strictly larger than zero, while non-negative numbers are the ones larger than or equal to zero. Hope this helps! Kind regards, 365 Hristina

If we know that "a is in A" and "b is in the intersection of A and B", then: a is part of B How could we conclude that a is part of B?. Let us assume that A = [a,b,c] B = [b,c,d] Now A intersection B equals [b,c]. In this case, a is not part of B, even though there is an intersection right?. so I'm confused?.

Hey Rahul, Thank you for reaching out! From the first two statements that you make 1. "a is in A" 2. "b is in the intersection of A and B" we can only conclude that 1. element 'a' is in set 'A' 2. element 'b' is in set 'A' 3. element 'b' is in set 'B' We cannot conclude that element 'a' is in 'B'. The intersection of two sets contains only the elements included in both sets. Hope this helps! Kind regards, 365 Hristina