Question 453994: which are related functions
1-{(5,7),(-2,1),(5,0),(-3,6)}
2-{(-2,-1),(4,5),(4,-2),(3,4)}
3-{(0,4),(3,6),(-1,2),(4,0)}
Answer by Edwin McCravy(20056)   (Show Source):
You can put this solution on YOUR website! Rule:
1. Look at all the first coordinates
2. Then ask the question: Are all those different?
3. If the answer is yes, then this is a function but if
the answer is no, then it is not a function.
Let's try it out on
1-{(5,7),(-2,1),(5,0),(-3,6)}
1. Look at all the first coordinates 5, -2, 5, -3
2. Then ask the question: Are all those different?
3. The answer is no because there are two 5's,
So it is NOT a function.
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Now let's try it out on
2-{(-2,-1),(4,5),(4,-2),(3,4)}
1. Look at all the first coordinates -2, 4, 4, 3
2. Then ask the question: Are all those different?
3. The answer is no because there are two 4's,
So it is NOT a function.
------------------------------------
Now let's try it out on
3-{(0,4),(3,6),(-1,2),(4,0)}
1. Look at all the first coordinates 0, 3, -1, 4
2. Then ask the question: Are all those different?
3. The answer is yes because none of them are the same.
So it IS a function.
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Easy, huh? Just look and see if all the first coordinates
are all different or whether some are the same. If they're
all different then you have a function. If some are the
same you don't. [By the way, it doesn't matter at all about
the second coordinates. They can be the same or different.
We only need to look at the first coordinates.]
Edwin
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