SOLUTION: Which of the following are functions? The last two problems, i.e., b & c, are multi part relations consider all parts when determining whether or not these relations are functions

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Question 308749: Which of the following are functions? The last two problems, i.e., b & c, are multi part relations consider all parts when determining whether or not these relations are functions. Explain your reasoning for a, b, and c.
a. f(x) = x + 3
b. f(x) = 73 if x>2 otherwise f(x) = -1
c. f(x) = 79if x>0 or f(x) = -9 if x<0 or f(x) = 9 or -9 if x = 0

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
The first two are functions.
For each value of x, you get a unique value of y.
.
.
.
However for the third one,
f%28x%29+=+9 or f%28x%29=-9 if x+=+0 fails the uniqueness test.
Therefore it's not a function.