How to tell if a relation is a function?

Jasian · **How to tell if a relation is a function? -** 09-10-2008, 11:01 PM

lol I know it's probably easy shit.. We're reviewing this right now but I dont remember learning about this.

Say you have..

Domain: 0, 0, 2, 2, 4, 4
Output: -4, -4, -3, -1, 1, 3

Or

Domain: -5, -4, -3, 0, 3, 4, 5
Output: -6, -6, -4, -4, -2, -2 ,-1

How can you tell if the relation is a function?

And also how do you tell if the function is linear?

example:

f(x) = x - 11;f(4)

mchlljy · 09-10-2008, 11:05 PM

in the domain there can't be 2 of the same number
first table: not a function
second table: function

also do the vertical line test

Jasian · 09-10-2008, 11:06 PM

Originally Posted by mchlljy

in the domain there can't be 2 of the same number
first table: not a function
second table: function

also do the vertical line test

wow lol that was simple

ok thanks. still need help on the linear function though >_<

mchlljy · 09-10-2008, 11:07 PM

oh and for

f(x)=x-11 f(4)
plug the 4 into all the x's you see

f(4) = (4) - 11
f(4) = -7

got it?

Yokee Lazy Boy · 09-10-2008, 11:21 PM

linear functions are the ones with degree of 1...
for example, 2x+1 would be a linear, and 2x^2 +1 would NOT...(because its squared/has degree of 2)

also linear functions would graph a straight line....

VicValSwift · 09-10-2008, 11:32 PM

If it has a variable of Ax(squared) it's not linear.

Like said above, also graph the function and use the vertical line test; if two points are on the same vertical positioning, then it is not a function.

I'm learning about functions as well, and although I grasp the concept and understand it.. I am BAFFLED by how any of it ties into.. anything at all, LOL.

Ironically enough, I hate math. Love literature, books, and the idea of knowledge. >.<

Yokee Lazy Boy · 09-10-2008, 11:39 PM

Originally Posted by VicValSwift

I'm learning about functions as well, and although I grasp the concept and understand it.. I am BAFFLED by how any of it ties into.. anything at all, LOL.

lol its just exercise for your brain, helps you with thinking skills, but doesnt teach you shit...

I love math, I hate homework, so no more math class for me...

mixedwell · 09-10-2008, 11:44 PM

Originally Posted by mchlljy

in the domain there can't be 2 of the same number
first table: not a function
second table: function

also do the vertical line test

YeeeEEe.
I dislike like graphing.
But I like drawing step graphs. hahaha

mchlljy · 09-10-2008, 11:46 PM

Originally Posted by mixedwell

YeeeEEe.
I dislike like graphing.
But I like drawing step graphs. hahaha

i hate graphing too
thank god for the graphing calculator
i only like step graphs cuz of the fun pattern they make lol

bboyimaginasian · 09-10-2008, 11:54 PM

WTF is this ive never seen anything like this in my whole 11 years of schooling......damn public schools

k3V1n · 09-11-2008, 12:41 AM

I'm learning the same thing at the same time as you steve :P

VicValSwift · 09-11-2008, 01:02 AM

^Word that's why I recognized it so easily.. just learned about it today LOL.

On the real.. I HATE graphing, especially what we're learning now.. It's not that it's all too hard.. it just takes a fucking SHITload of time to do a simple little graph!

It takes me a little over an hour to do ONLY about 30 or so problems of graphing/functions/etc. (algebra 2) yet they're so easy by the last few I'm thinking "This took ages to do.."

Mr. Flapps · 09-11-2008, 01:06 AM

Do the vertical line test

bboybendy · 09-11-2008, 01:08 AM

for function testing: no output should be the same.
For linear: y=mx+b format. if there is ^ sign, its parabolic

i think thats what you do -.-"

YoungJ.R. · 09-11-2008, 11:26 AM

haha i love math...wait till u get to trig and calc. major fun bro!!!! seriously!!


Jasian Bboy Respect: 5.5 Posts: 1,352 Join Date: Nov 2007 Location: Hillsboro	How to tell if a relation is a function? - 09-10-2008, 11:01 PM lol I know it's probably easy shit.. We're reviewing this right now but I dont remember learning about this. Say you have.. Domain: 0, 0, 2, 2, 4, 4 Output: -4, -4, -3, -1, 1, 3 Or Domain: -5, -4, -3, 0, 3, 4, 5 Output: -6, -6, -4, -4, -2, -2 ,-1 How can you tell if the relation is a function? And also how do you tell if the function is linear? example: f(x) = x - 11;f(4)


mchlljy ADVENTUREEEEEEER! Respect: 2 Posts: 558 Join Date: May 2008	09-10-2008, 11:05 PM in the domain there can't be 2 of the same number first table: not a function second table: function also do the vertical line test
	Now you see that I am 68 inches above sea level, 93 million miles above these devils.


mchlljy ADVENTUREEEEEEER! Respect: 2 Posts: 558 Join Date: May 2008	09-10-2008, 11:07 PM oh and for f(x)=x-11 f(4) plug the 4 into all the x's you see f(4) = (4) - 11 f(4) = -7 got it?
	Now you see that I am 68 inches above sea level, 93 million miles above these devils.


Yokee Lazy Boy Member Respect: 1.5 Posts: 188 Join Date: Jun 2005 Location: Los Angeles	09-10-2008, 11:21 PM linear functions are the ones with degree of 1... for example, 2x+1 would be a linear, and 2x^2 +1 would NOT...(because its squared/has degree of 2) also linear functions would graph a straight line....
	“You can’t just do it two hours a day and 'yeah ok ill do it when I go to the jam', we used to eat, shit, piss, drink, and think b-boying"


VicValSwift Emcee/B-Boy Respect: 7 Posts: 2,753 Join Date: May 2006 Location: Frisco, Cali	09-10-2008, 11:32 PM If it has a variable of Ax(squared) it's not linear. Like said above, also graph the function and use the vertical line test; if two points are on the same vertical positioning, then it is not a function. I'm learning about functions as well, and although I grasp the concept and understand it.. I am BAFFLED by how any of it ties into.. anything at all, LOL. Ironically enough, I hate math. Love literature, books, and the idea of knowledge. >.<


bboyimaginasian Member Respect: 1.5 Posts: 612 Join Date: Jun 2008	09-10-2008, 11:54 PM WTF is this ive never seen anything like this in my whole 11 years of schooling......damn public schools
	I PA PA PA POKE HER FACE PA PA POKE HER FACE


k3V1n Member Respect: 5.5 Posts: 1,096 Join Date: Aug 2007	09-11-2008, 12:41 AM I'm learning the same thing at the same time as you steve :P


VicValSwift Emcee/B-Boy Respect: 7 Posts: 2,753 Join Date: May 2006 Location: Frisco, Cali	09-11-2008, 01:02 AM ^Word that's why I recognized it so easily.. just learned about it today LOL. On the real.. I HATE graphing, especially what we're learning now.. It's not that it's all too hard.. it just takes a fucking SHITload of time to do a simple little graph! It takes me a little over an hour to do ONLY about 30 or so problems of graphing/functions/etc. (algebra 2) yet they're so easy by the last few I'm thinking "This took ages to do.."


Mr. Flapps IM BLACKANESE Respect: 6 Posts: 2,449 Join Date: Jul 2006 Location: san jose	09-11-2008, 01:06 AM Do the vertical line test


bboybendy Im an e-boy. Respect: 3.5 Posts: 994 Join Date: Oct 2007	09-11-2008, 01:08 AM for function testing: no output should be the same. For linear: y=mx+b format. if there is ^ sign, its parabolic i think thats what you do -.-"
	The resident otaku.


YoungJ.R. Tracuer turning bboy Respect: 1.5 Posts: 123 Join Date: Aug 2008 Location: Fort Worth	09-11-2008, 11:26 AM haha i love math...wait till u get to trig and calc. major fun bro!!!! seriously!!

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