Question 184843
# 1


Note: I'm assuming that the endpoints aren't included.



Remember, roster form simply means that you write out EVERY element in the set. So start at 10 (but don't include it) and count 11, 12, 13, etc until you reach 16 (and don't include it). 


So the set N in roster form is:


*[Tex \LARGE N=\left\{11,12,13,14,15\right\}]



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# 2



Original Set


*[Tex \LARGE Z = \left\{2, 3, 4, 5, 6, 7, 8, 9, 10\right\}]



Set Builder Notation (simply an abbreviation of the first set)


*[Tex \LARGE Z = \left\{x\|x\in\mathbb{N} \ \ and \ \ 2\le x \le 10\right\}]


Note: the big "N" is the set of natural (ie counting) numbers



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# 3



*[Tex \LARGE A=\left\{x\|x\in\mathbb{N}\ \ and \ \ 13<x<18\right\}]



*[Tex \LARGE A=\left\{14, 15, 16, 17\right\}]



*[Tex \LARGE B=\left\{12,13,14,15,16,17,18\right\}]



Notice how ALL of the elements of set A are also elements of set B, so this shows us that set A is a subset of set B (ie all of A is in B). So *[Tex \LARGE A \subseteq B]


Note: the two sets A and B are NOT equal since set B has the element 12 (but set A does NOT have the element 12)