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Can someone help me please? I need to find which of these is a function and I have no clue which is the answer.

1 Answer

Jun 26, 2018

Only the fourth example is a function.

Explanation:

What you need to look at is whether there are any values of the independent variable $x$ $x$ which map onto more than one dependent variable $y$ $y$ . To be a function there can not be any duplication,

In the first example
$XXX 3$ $color(white)("XXX")3$ is mapped onto both $- 5$ $-5$ and $0$ $0$
So it is not a function.

In the second example
$XXX - 1$ $color(white)("XXX")-1$ is mapped onto both $- 11$ $-11$ and $5$ $5$
So it is not a function.

In the third example
$XXX 3$ $color(white)("XXX")3$ is mapped onto both $14$ $14$ and $19$ $19$
So it is not a function.

In the fourth example
$XXX$ $color(white)("XXX")$ There is no place where two points (values of $y$ $y$ )
$XXX$ $color(white)("XXX")$ are identified (mapped from) any value of $x$ $x$
So it is a function.

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