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Adv. Algebra


Cmdr. Cracken

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Posted

a function is anything that passes the the y axis only once.

 

for instance

 

f(x)=2x(sq)+x

 

if you give a number say 4 you get.

 

2(4)(sq)+4=36

 

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"Dulce bellum inexpertis."

(Sweet is war to those who have never experinced it.) Roman Proverb

Posted

Originally posted by Admiral:

a function is anything that passes the the y axis only once.

 

NO!!! That is not true at all! It is true that if it does pass the y axis more than once, it is not a function, but it needs much more to actually be a function.

 

A function is a mapping from one set of values to another. The key is that no element from the domain ("mappers") can map to more than one element of the range ("mappees"). Now, two or more elements of the domain can map to the same member of the range - that makes no difference. So if you think about it in terms of the graph, no two points can be on top of each other. The graph cannot cross ANY vertical line more than once.

 

Guest Zoom Rabbit
Posted

I function as a biological perambulation unit!

Posted

Your right Keyan. I haven't used functions for over a year so...must have forgotten some. we need to chat some math some time.

 

Cracken if you can post some problems I could help some more.

 

 

------------------

"Dulce bellum inexpertis."

(Sweet is war to those who have never experinced it.) Roman Proverb

Posted

Originally posted by Admiral:

a function is anything that passes the the y axis only once.

 

Admiral, you should have known better. f(x) = 1/x is a function, but it never actually passes the y-axis.

 

 

 

Posted

I think i know what R9 is getting at. a function is any line on a graph that passes the vert. Line test.

 

Vertical line test=You place a vertical line anywhere on the line. if the vertical line crosses the line more than ONCE, then the line is not a function.

 

R9's sentence (x-4)^2/x-2 will probably fail this test.

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