1.	Select the relation that is a function.
		A.	{(-2, -1),(5, -1), (16, 3), (-3, -9)}
		B.	{(21, 11), (21, 10), (21, 9), (21, 8)}
		C.	{(-6, -5), (3, 2), (10, 8), (3, 3)}
		D.	{(5, 10), (-3, 10), (-3, -10), (4, 7)}
		Hint
	2.	Which relation is not a function?
		A.	{(-2, 1), (2, 3), (6, 5)}
		B.	{(2, 4), (3, 5), (2, 7)}
		C.	{(1, 1), (2,2), (3, 3)}
		D.	{10, 0), (2, 4), (-2, 4)}
		Hint
	3.	Which of the following is (are) true about functions?
		A.	Functions are relations.	B.	Functions pass the vertical line test.
		C.	All of these	D.	In a function, each member of the domain is paired with one and only one member of the range.
		Hint
	4.	Functions can be expressed using which of these?
		A.	tables	B.	ordered pairs
		C.	all of these	D.	graphs
		Hint
	5.	Which graph is not a function?
		A.		B.
		C.		D.
		Hint