SOLUTION: I am very unsure when it comes to functions. Can you please help me to understand what makes something a function? Here is the question. Which of the following are functions?

Question 174588: I am very unsure when it comes to functions. Can you please help me to understand what makes something a function? Here is the question.
Which of the following are functions? Explain why/why not.
A. f(x)=2 if x>1 otherwise f(x)=-1
B. f(x)=5 if x>0 or f(x)=-5 if x<0 or f(x)=5 or -5 if x=0
C. f(x)=x/10
Any help I recieve would be greatly appreciated as I am so utterly confused.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A function is a set of ordered pairs with the following
restriction: Each x value must have only one y value
associated with it.
====================================
Which of the following are functions? Explain why/why not.
A. f(x)=2 if x>1 otherwise f(x)=-1
This is a function. Choose any value of x and the corresponding
y value will be 2 if x>1, or it will be -1 if x<=1
But each x value will have only one corresponding y value.
--------------------------------------------------------------
B. f(x)=5 if x>0 or f(x)=-5 if x<0 or f(x)=5 or -5 if x=0
Not a function because you have two points (0,5) and (0,-5)
Notice that x=0 has two associated y values, so not a function.
---------------------------------------------------------------
C. f(x)=x/10
This is a function; each x value has one y value associated with it.
=========================
Cheers,
Stan H.

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