Is (-4,1), (1,-8), (-2,-2) a function?

2 Answers
May 18, 2015

(-4,1), (1, -9) and (-2,-2) are just three distinct points.

They are not a function as such, but they could be used to define a function.

Let #D# be the set {-4, -2, 1}. This is the domain of the function.

Define #f:D->ZZ# by the explicit mapping:
#f(-4)=1#
#f(-2)=-2#
#f(1)=-9#

The range #R# of the function #f# is the set {-9, -2, 1} of values in #ZZ# which #f(x)# takes for #x# in #D#.

May 18, 2015

Yes, the set #{(-4,1), (1,-8), (-2,-2)}# is a function.

A function is a set of ordered pairs in which no two pairs have the same first element and different second elements.

This definition, in a way, tells us how a collection of ordered pairs call fail to be a function.

The set you asked about has no two pairs with equal first and different second elements. So it is a function.