Question

The domain of the following relation: R: {(−3, 4), (5, 0), (1, 5), (2, 8), (5, 10)} is:

A.) {−3, 1, 2, 5}
B.) {4, 0, 5, 8, 10}
C.) {−3, 5, 1, 2, 5}
D.) No domain exists

Answer 1

The domain of the given set of numbers are the values of abscissa. From the given the values of the abscissa are: -3, 5, 1, 2. Therefore, the answer to this item is letter A. 5 need not be written twice. 

Answer 2

For an ordered pair (x,y) that a set contain :

x = Domain of the relation

y = Range of the relation

In a relation x can have two or more than two ranges i.e a x can have more or more than two images.

So, Domain = First element of ordered pair that the following relation R contains ={(−3, 4), (5, 0), (1, 5), (2, 8), (5, 10)}= -3, 5, 1,2,5

But the element 5 is Occuring twice.

Domain = { -3,1,2,5} →→Option A