Belle E.

asked • 08/23/17# Which of the following expressions represents a function?

{(1, 2), (4, –2), (8, 3), (9, –3)}

y2 = 16 − x2

2x2 + y2 = 5

x = 7

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## 2 Answers By Expert Tutors

Andy C. answered • 08/23/17

Tutor

4.9
(27)
Math/Physics Tutor

The first and last are functions. Every value of x in the domain is mapped to one and only one value of y in the range.

That is not the case with the 2nd and 3rd examples . for example, in the second case, the value x=0 maps to both 4 and -4.

Carol H. answered • 08/23/17

Tutor

4.9
(285)
Masters' Degree in Mathematics with 35 years of Teaching Experience

{(1, 2), (4, –2), (8, 3), (9, –3)} is the function because every x-value has only one y-value.

The other three would not pass the vertical line test for a function.

y

^{2}= 16 − x^{2}is the equation of a circle;2x

^{2}+ y^{2}= 5 is the equation of an elllipse; andx = 7 is the equation of a vertical line.

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Carol H.

08/23/17