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

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Answer 1 · 2015-05-18T22:51:12

(-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 $D$ $D$ 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 $D$ .

Answer 2 · 2015-05-18T23:51:07

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.