What is a function?

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Answer 1 · 2018-03-25T15:37:14

A function is a set of ordered pairs (points) formed from a defining equation, where, for each $x$ $x$ -value there is only one $y$ $y$ -value.

$x - - - - - - \to y$ $x-------> y$ represents a function

This means that you can choose an $x$ $x$ -value and plug it into an equation, usually given as:

$y= ....." " or" " f(x)= .....$

This will give you a $y$ -value.

In a function there will be only ONE possible answer for $y$ .

If you find you have a choice, then the equation does not represent a function.

The following are functions:

$y=-3$

$y=3x-5$

$y = 2x^2-3x+1$

$(1,2), (2,2), (3,2),(4,2)$

The following are NOT functions:

$x= 3$

$y=+-sqrt(x+20)$