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Question 17636: Hi, Goog morning, I am having a math test on Monday and I need a little help recognizing functions and non functions . Do you think you can help me understand? I am an A student and would like to get as much help as I can
Answer by venugopalramana(3286)   (Show Source):
You can put this solution on YOUR website! HOPE THE FOLLOWING WILL HELP YOU IN YOUR TROUBLE.IF YOU WANT MORE ASK PLEASE
my problem states tell if the relation of the graph is a function
and the set of ordered pairs are (-2,3) (-4,3) (-6,3) (2,-1) (4,-1) (7,-1)
and they want to know is there a function now i dont know i think its not..but could someone please help me so that i can be more sure about it?
........make a set of first numbers in the above ordered pairs ...call it set A
..set A =(-2,-4,-6,2,4,7)
similarly make a set of second numbers and call it set B
...set B = (3,3,3,-1,-1,-1)=(3,-1)..to see whether the change from set A to ...set B is a function ..check
1.each and every element in set A has corresponding number in set B
it has so ok.
2.each and every element in set A has a unique corresponding number in set B.we find it ok.PLEASE NOTE THAT UNIQUE MEANS ONE NUMBER IN SET A CANNOT HAVE 2 CORRESPONDING NUMBERS IN SET B .WHERE AS TWO OR MORE NUMBERS IN SET A CAN HAVE SAME CORRESPONDING NUMBER in set B.
....if the above 2 conditions are satisfied we say set A to set B is a function..so the given one is a function.
at the same time note that set B to set A is NOT REPEAT NOT a function
since test 2 fails namely 3 in set B has not one but many corresponding numbers ( called images) like -2.-4.-6.so the correspondence or image is not unique and hence it is not a function.if we write as ordered pairs ,then it can be a function from 1st. set to 2nd.set only when there are no repetetions in the first numbers having different images in the second numbers.and vice versa for it to be a function from 2nd. set to 1st. set
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