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| Question 1000900:  1(a) Given the universal set U={1,2,3,…,9} and the sets
 A={1,2,3,4,5};  B={4,5,6,7};  C={1,3,5,7,9}; D={2,4,6,8}.
 
 Find
 (i)B-A
 (ii)(A-D)c
 (iii)(A⋂C)\B
 
 Question 2(a)
 Given the functions f and g be defined by f(x) = 5x-4 over
 8x-7
 and g(x) =3x2-4. Find the formula defining the composition function gοf and fog.
 
 Question 2 (b)
 Consider the relation R= {(1,a); (2,d); (3,a); (3,b); (3,d)} and  S= {(b,x); (b,z), (c,y); (d,z)}.Find S-1 o R-1
 
 
 Answer by Edwin McCravy(20064)
      (Show Source): 
You can put this solution on YOUR website! 1(a) Given the universal set U={1,2,3,…,9} and the sets A={1,2,3,4,5};  B={4,5,6,7};  C={1,3,5,7,9}; D={2,4,6,8}.
 
 Find
 (i)B-A
 
 
That's the set of all elements of B that are not elements of B
From B = {4,5,6,7}, we take out any of these A={1,2,3,4,5} which
B contains.  A contains 4 and 5, which A also contains, so we 
remove 4 and 5 from B and we have {6,7}.
Therefore B-A = {6,7}
                                                          
(ii)(A-D)c
We first find what's in the parentheses, A-D
From A={1,2,3,4,5}, we take out any of these D={2,4,6,8} which
A contains.  D contains 2 and 4, which A also contains, so we 
remove 2 and 4 from A and we have {1,3,5}.
So A-D = {1,3,5}
So to find the complement of that set, (A-D)c,
we form the set of all elements in the universal set U={1,2,3,…,9}
which are not elements of A-D, which is {1,3,5}. So we remove
1,3 and 5 from the universal set U={1,2,3,…,9} and we have
{2,4,6,7,8,9}
So (A-D)c = {2,4,6,7,8,9}
We are only supposed to answer 2 questions per post.
Edwin
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