Math question

[Onkel Neal]

Ok, so I am refreshing myself with some math. I am going over Slope-Intercept Form of a line

y=mx+b

and,

"point-slope" form of the equation

Is this the same thing? I guess not. (http://en.wikipedia.org/wiki/Linear_equation)

And then you have General Form, Ax + By + C = 0
What's the C? It seems to be missing from the other formulas :O: As well as the A & B?

[vienna]

Just reading that gave me the same mind-numbing, out-of-body feeling I used to get in high school...

Thanks for the cheap high, Neal... :D

(Oh, and if I remember correctly, the answer is always "B"...)

...

[Gargamel]

They are the same. *Just solve for y.

Ax + By +C = 0

Becomes

y = -(A/B)x -(C/B)

So in y=mx+b

m = -(A/B)
And
b= -(C/B)

(note upper/lower case)

[the_tyrant]

use wolfram alpha (http://worlframalpha.com)

it is a math student's best friend

[Gargamel]

Except for when I'm trying to use it to estimate the cost of welding jobs. When I ask for the mass of given volume of steel, it gives me the price of steel futures. Wtf ?

It wont help him learn how the equation works either.

[Onkel Neal]

They are the same. *Just solve for y.

Ax + By +C = 0

Becomes

y = -(A/B)x -(C/B)

So in y=mx+b

m = -(A/B)
And
b= -(C/B)

(note upper/lower case)

How did it become that second line?


Ax + By +C = 0

Subtract C from both sides:
Ax + By = -C

Subtract Ax from both sides:
By = -C -Ax

Divide both sides by B:
y = (-C -Ax)/B

How does it become:
y = -(A/B)x -(C/B) ??

I have been watching instructional videos which are great except often the person who KNOWS how to do this forgets the pupil does NOT and assumes he does. :dead:

For example, I'm following along and then at :46 mark, (http://www.youtube.com/watch?v=vqqu0QYBGJ8) bang! Where did out friends A, B, and C disappear to?? :o

[U570]

Ax+By+C=0 then
By= -Ax-C and then
y=-(Ax/B)-(C/B)
-(Ax/B) is just the same as -(A/B)x
and here we have:
y=-(A/B)x-(C/B)
I hope this solve your dilemma Neal.

[Onkel Neal]

Yes, thanks, I just have to do about 300 examples to imprint it in my brain.

I learned this stuff about 4 times in my life... but it never gets used.

[CaptainHaplo]

I want the 90 seconds back that it took me to read this!

My brain hurts now... HOPE YOUR HAPPY!

[Madox58]

I saw Math Question and STILL clicked on the topic!!
:nope:

My head hurts!!
:doh:

[Pisces]

Coincidentally, I just watch this:

http://tauday.com/

Makes sense.

[PeriscopeDepth]

Hey Neal,

Both:
http://www.khanacademy.org/#browse
http://patrickjmt.com/

are fantastic resources. Made my courses much more bearable for me.

PD

[Madox58]

Do not seek the treasure! (http://www.youtube.com/watch?v=NPjhEsZr8Nw)
:haha:

[Gargamel]

Bah

Math is fun. Dunno what you guys are crying about. :D

[Sailor Steve]

I'm crying because it hurts just to look at it.

My older daughter is a math genius. I'm a math idiot. I can never figure out manual targetting. I'm real good with simple arithmetic, but as soon as there are letters involved I'm lost. This is funny because I'm pretty good at letters too. I guess it's like politics and religion - numbers and letters don't mix for me.

[Platapus]

Math is exactly like a language. If you don't use it you lose it.

I have forgotten so much about my maths. :nope:

[Seth8530]

I miss the days when my math was just linear equations ) : Today, I actually ended up spending four hours worth of my time, and 11 pages of paper solving second order differential equations for my Differential equations course today... Hell of a way to spend a Saturday /:

[U570]

I miss the days when my math was just linear equations ) : Today, I actually ended up spending four hours worth of my time, and 11 pages of paper solving second order differential equations for my Differential equations course today... Hell of a way to spend a Saturday /:
This and doing 3 pages per question on curve sketching are about par. Guess what I have to do for school:yawn:

[Seth8530]

hehe indeed, Damn springs, and damn dampening coefs, One of them buger s did take me three pages to work out.. First time in a long time mathematics has taken that much work from me, its usually the engineering courses.

[Gargamel]

http://i.imgur.com/zoawk.jpg

Warning, bad language.

[THE_MASK]

I'm crying because it hurts just to look at it.

My older daughter is a math genius. I'm a math idiot. I can never figure out manual targetting. I'm real good with simple arithmetic, but as soon as there are letters involved I'm lost. This is funny because I'm pretty good at letters too. I guess it's like politics and religion - numbers and letters don't mix for me.People keep asking me what manual targeting mods i use and how do i do it . I dont reply and hope they go away because i havnt got a bloody clue :haha:

[Jimbuna]

People keep asking me what manual targeting mods i use and how do i do it . I dont reply and hope they go away because i havnt got a bloody clue :haha:

LOL :DL

[Onkel Neal]

I saw Math Question and STILL clicked on the topic!!
:nope:

My head hurts!!
:doh:

Lol, :rotfl2:

Hey Neal,

Both:
http://www.khanacademy.org/#browse
http://patrickjmt.com/

are fantastic resources. Made my courses much more bearable for me.

PD

Yes, thanks, PD, I have been using Khan like crazy for the last three weeks, that really helps.



Bah

Math is fun. Dunno what you guys are crying about. :D

Well, some people think playing with model trains is fun and collecting antiques is fun, I think it's boring as hell. The only math I enjoy is that to which I can apply practical applications, like manual torpedo targeting, probablities, and percentages. The rest is abstract fluff that only engineers need to know. :shifty: And math teachers :smug: My goal is to get up to speed and help students by identifying with them and finding ways to make math interesting and not so daunting. "Are you intimidated by advanced math concepts? Me too! But I can show you ways to learn it and become proficient without breaking your brain". Of course, some brain-breaking will be necessary, but we can ease into it.



I'm crying because it hurts just to look at it.

My older daughter is a math genius. I'm a math idiot. I can never figure out manual targetting. I'm real good with simple arithmetic, but as soon as there are letters involved I'm lost. This is funny because I'm pretty good at letters too. I guess it's like politics and religion - numbers and letters don't mix for me.

I can perform math at the college level without too much difficulty, but like Plat says, you don't use it, you lose it. And I never used it in real life.

I cannot wait to attend a party and while the guests are discussing literature, philosphy, politics, history, travels... etc, I'll spring the delightful subject of recursive expansions on them. How they will love me!:arrgh!:

[Onkel Neal]

@ Gargamel

While doing the exercises at Khan Academy, finding the slope of a line, there was one example where the text shows

m = y1-y2/x1-x2

Now, that's different from everything else they show, and everything else I can find on the web, where slope is clearly defined as

m = y2-y1/x2-x1

That's the correct definition, right? There's no y1-y2 version is there? Or does it not make a difference? :dead:

[Kaleun]

I'm an IT engineer now - but i like Maths (as we call it in the UK), i have a degree (Bsc) in the pesky subject!

[Diopos]

@ Gargamel

While doing the exercises at Khan Academy, finding the slope of a line, there was one example where the text shows

m = y1-y2/x1-x2

Now, that's different from everything else they show, and everything else I can find on the web, where slope is clearly defined as

m = y2-y1/x2-x1

That's the correct definition, right? There's no y1-y2 version is there? Cause that changes the sign... :dead:

The expressions are equivalent:
m = y1-y2/x1-x2=[(y1-y2)]/[(x1-x2)]=[-(y2-y1)]/[-(x2-x1)]= (y2-y1)/(x2-x1)

[U570]

@ Gargamel

While doing the exercises at Khan Academy, finding the slope of a line, there was one example where the text shows

m = y1-y2/x1-x2

Now, that's different from everything else they show, and everything else I can find on the web, where slope is clearly defined as

m = y2-y1/x2-x1

That's the correct definition, right? There's no y1-y2 version is there? Or does it not make a difference? :dead:
just a heads up about the y2-y1 and x2-x1; they are the co-ordinates of the line you are trying to find the gradient of. Just imagine the line goes through (0,0) and (3,7). The co-ordinates are as such;
y1=0, y2=7, x1=0, x2=3
sub them in accordingly; and you get
m=7-0/3-0
m=7/3
Does that help with it?

[nikimcbee]

You lost me at the word math.

[Sailor Steve]

Okay, I bookmarked the Khan thing. I'll try to see if I can learn anything.

[Onkel Neal]

just a heads up about the y2-y1 and x2-x1; they are the co-ordinates of the line you are trying to find the gradient of. Just imagine the line goes through (0,0) and (3,7). The co-ordinates are as such;
y1=0, y2=7, x1=0, x2=3
sub them in accordingly; and you get
m=7-0/3-0
m=7/3
Does that help with it?

Yeah, thanks, I know that much, I was not sure about the sequence.

[Seth8530]

@ Gargamel

While doing the exercises at Khan Academy, finding the slope of a line, there was one example where the text shows

m = y1-y2/x1-x2

Now, that's different from everything else they show, and everything else I can find on the web, where slope is clearly defined as

m = y2-y1/x2-x1

That's the correct definition, right? There's no y1-y2 version is there? Or does it not make a difference? :dead:

There are equivalent because with the first equation say you get -3/1 after the calculation. with the second one using the same numbers you would get 3/-1 which are equivalent.

[Gargamel]

The sequence doesnt matter too much as long as you keep to pairs together. (x1,y1) & (x2,y2).

Think of it as plotting an intercept for a convoy. :D

[Dan D]

@Neal

Next time you get pulled over by the police for not stopping at a stop sign you can fight the ticket with your new math skills:

The Proof of Innocence (http://arxiv.org/pdf/1204.0162v1.pdf)

Date of article is 1.April 2012 though, could be a mathematician joke. Is it?

[Gargamel]

The paper is real, but it's not why he got out of the ticket.

[Dan D]

The paper is real, but it's not why he got out of the ticket.

What do you mean when you say:"it's not why he got out of the ticket"?

[Onkel Neal]

@Neal

Next time you get pulled over by the police for not stopping at a stop sign you can fight the ticket with your new math skills:

The Proof of Innocence (http://arxiv.org/pdf/1204.0162v1.pdf)

Date of article is 1.April 2012 though, could be a mathematician joke. Is it?

Beautiful!

The sequence doesnt matter too much as long as you keep to pairs together. (x1,y1) & (x2,y2).

Think of it as plotting an intercept for a convoy. :D

There are equivalent because with the first equation say you get -3/1 after the calculation. with the second one using the same numbers you would get 3/-1 which are equivalent.


Yeah, thanks, I finally proved that out to my satisfaction.

[Gargamel]

The judge ruled the cop was too far away to see the intersection. It had nothing to do with the paper.

There was a physicist here in Cleveland at NASA that got out of a speeding ticket a while though. He tried to show the radar gun couldn't be used as the cop was using it. The judge didn't buy it until the physicist showed the judge the patent for the radar gun, with his name on it.

[NeonSamurai]

Heh if you guys want painful math, I remember doing my stats courses for psychology. The worst by far though was Psychometrics (http://en.wikipedia.org/wiki/Psychometrics) using formulas like this one Cronbach's Alpha (http://en.wikipedia.org/wiki/Cronbach%27s_alpha)<shudder>.

[Gargamel]

http://funnypictures.s3.amazonaws.com/d97dd7a1-5673-46da-8071-7d2c5b53970d.jpg

[Diopos]

http://funnypictures.s3.amazonaws.com/d97dd7a1-5673-46da-8071-7d2c5b53970d.jpg

Good one!

:yep:

:har:

:up:

.

[Seth8530]

Alright, since it appears we are playing trivia, lets see how long it is before some one answers this one... Without cheating!! Not that it is hard, but just a little tricky. (as I learned in my differential equations course.)


1) e^-ln(x)

2) http://www.subsim.com/radioroom/data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZoAAAA4CAIAAAB Lx6llAAAEgElEQVR4nO3dLVPrTBjG8RWIyopKRAWiogKBeDJTG YFEIBAVCGanAoFAIJiJxKWiH6CSD8Cc2H4EBIKZVFREICoqEMg 8oi/kZbNp022bhv/PnDmT9M4eca7Ze/OyIjQkCIKrq6tardbtdk3VBID1CVOFLi4uxuOx4zjNZtNUTQBY n5k4G41G19fXRkoBQDFm4uzp6en5+dlIKQAoxkycXV5evry8GC kFAMWYibOzs7PhcGikFAAUYybOTk9PiTMAh2UmzoQQr6+vRkoB QDHG4mw0GhkpBQDFEGcAKsJAnE2nU+IMwMEZiLPJZHIscRYEwe 3tbe5p3W53PB7vYTwADPpDcTabzTqdzmQyyT1zMpmcn59/fX1tUN13LSEs1y88PABbOnic+a4llnRpED1PCCGkt+mVer1e5r O+npu4dL/fX2cet/y5VPwDUjUB7NRh48x3rVUCzCNBO7+ZR9rmQRaG4XQ6bTQas9lM edSTyaLf39/1en2TltOT8dGnawLYKQNx9v7+XjDOfM+Lhlduv+a7VtF+bjAYd Dod9TFPKqvatt3v99e+QjzOMmoC2B0DcTYajQytnSUnOAmZabZ sRJcHF71f9NybmxvVh9iWXaKqf727u8v7TEjk51IuB6+rCWB3y hRnOZMv37U08eC7lpDe75/zaFwdbrfb9/f3uh+mOI7TarW0o10NdxGo0b8SZMCelSjOcvozfZp5UgjphZ5c lEieXavVHMfJKKu+rOM4Jycn644mmm5bNMUACttpnP2Ltl0r6i rRuwJK2k7Udy1hSWmtAiZ5thBCHWfZIeo4jm60yWyNXJGFM+AQ SjI7yw2z/DSLLVSlzs6Ks8WsTkUXZ55MrYv9XlJTE8DulCLOPJn731+RH5q j6ezLaDZ1i1y6ZtOTqYdKVtdk4Qw4DGNx9vHxUezniSzzXamYg 2UsnC1OTqaXYu1KfStAu8ilvRWQzrPlIFg4Aw7EWJyt8/JQmpdeXVNEgfrx2dh0KJlmQnq+K3/vbKof1EjeQIjRP6iR6G9/X1po/aepCWB3DMTZ29tbsThTZFkqzZLvNsVJL1TM3BSPnWU8Rrs4U90 a5j5GG38/y100vNqaAHbHQJwNh8PCs7O90b/klPbz89NoNPiuBnBE/kqchfpX0FMGg8EGr6ADKIE/FGez2azdbq8z4Zp/SigIgj2MCoApfyjOwjAMgmCd3dp7vR5tJnB0jMXZ+stSALALxu Js+zoAsA3iDEBFEGcAKsJMnNXr9e3rAMA2DMRZv9/P/G41AOyLgTh7fHwcDAbb1wGAbRSPs2az+fDwEIahbds8pQHg4Ir HmW3b84+IfX5+GhwQABTDHUkAFUGcAagI4gxARejjLPqBRT6uC qDUMuNsnmTLb6rqdx4BgMNTx1lyY4/Yjt8AUEaqOFNt88bcDEDJpeMstm0S+3gAOBapOItvnUSDCeBYp OKMzhLAccqIs/Rul8zTAJRb1tpZJNA8Sc8JoPyUD2rEtyen8QRwDHjJCUBFEGcA KoI4A1ARxBmAiiDOAFTE/9VGb6tyckt6AAAAAElFTkSuQmCChttp://s15.postimage.org/6qvwy3987/integral.jpg (http://postimage.org/image/6qvwy3987/)

Have fun, no cheating.

BTW @ Neal, you are correct, the biggest part about doing maths or any thing that is abstract is not reading it in a book or seeing that it is true online. But actually proving to yourself that yes, this does indeed work.. Then, it truly becomes your tool to use.

[Spoon 11th]

1+2=12