[ 3 / biz / cgl / ck / diy / fa / ic / jp / lit / sci / vr / vt ] [ index / top / reports ] [ become a patron ] [ status ]
2023-11: Warosu is now out of extended maintenance.

/sci/ - Science & Math

View post   
File: 11 KB, 210x208, every869.jpg [View same] [iqdb] [saucenao] [google]
4437873 No.4437873 [Reply] [Original]

My calc teacher asked for the function which is the derivative of it's self. I provided two, f(x) = 0 and f(x) = e^x.

Why did she mark me off?

>she

>> No.4437880

maybe she wanted c*e^x ?

>> No.4437878

Because f(x) isn't a function. It's an expression.

>> No.4437881

Because she's a big cunt

>> No.4437888
File: 15 KB, 432x288, 1298971996116.jpg [View same] [iqdb] [saucenao] [google]
4437888

>teacher not telling you why she marked you off

>> No.4437893

0 is not a function, it is an integer is all I can think, but I wouldn't think they would mark off too much for that

>> No.4437896

>>4437893
I recommend against ever speaking to anyone about math. You aren't very good at it.

>> No.4437905

Could be a notational thing. Maybe she expected you to explicitly write down the domain and codomain. Although that's pretty much nitpicking.
Either way, she should definitely give you a reason for marking you off.

>> No.4437912

>>4437896
because f(x)=0 totally relates an input to an output instead of just being a constant fixed integer?

>> No.4437915

>>4437912
Yes.

>> No.4437918
File: 108 KB, 500x375, skeptical.jpg [View same] [iqdb] [saucenao] [google]
4437918

>>4437912

f(x)=0 implies f(x)=x where f''(x) = 0 faggot

therefore the function f(x)=0 is a function where the derivative of the derivative is itself

QED that teacher should lick my taint

>> No.4437919

>>4437915
can you back this up with evidence?

>> No.4437922

>>4437919
Have you ever heard the term "constant function"? Math is based on definitions, and you are on the wrong side of this definition.

>> No.4437924

>>4437919

>input a number
>output exactly one number

It's a function jackass

>> No.4437923

>>4437919

Yes.

Number one, that's terror.

>> No.4437928

Also, 0 is not simply a derivative of itself, but of any constant, either way, I think the reason you got marked off on a technicality was the addition of f(x)=0.

>> No.4437931

>>4437928
If this were the case there woukd be no answer. e^x is the derivitive of e^x + 2, for instance.

>> No.4437954

you didn't provide all solutions. its ce^x. with c any number. c=0 includes 0 then too.

>> No.4437956

f(x)=0 and f(x)=e^x are not functions.
x -> 0 and x -> e^x are functions.
So are λx.0 and λx.e^x

You probably got marks off because every multiple of the exponential function is the derivative of it's self and you didn't prove your assertion.

>> No.4437962

>>4437893

nope.avi

<span class="math">\displaystyle f(x) = 0x^{0}[/spoiler]

Your teacher is a cunt, OP.

>> No.4438005

Your teacher secretly loves you and by marking you off she thought you'd show up her officer to demand explanation, it was just an excuse to see you again.

>> No.4438023

>>4437956

>f(x)=0 and f(x)=e^x are not functions.
>x -> 0 and x -> e^x are functions.

Oh shit nigger what are you doing

>> No.4438029

>Why did she mark me off?

Because the general solution is f(x)=c*e^x.

>> No.4438034

>>4437912
Yes, it relates all inputs to 0.

>> No.4438035

>>4437873
Post your entire solution and we can tell you. You might not have proven that these functions have derivatives equal to their own values, you might not have derived it from the question (setting up the differential equation and solving it), or, as stated, it might be because you didn't give the general solution.

Also, /sci/ are not mind readers. Try asking /x/ or your teacher.

>> No.4438046

>>4437956
Okay. Somewhere along the way, you went full retard.

>> No.4438050

>>4438035
OP wanted to know if he was wrong, jackass. Quit getting your panties in a bunch.

>> No.4438076

If it's highschool calc she's probably a retard

If it's college calc, she probably wanted c*e^x or your TA is a retard/asshole

>> No.4438093

You provided two answers, when she asked for only one solution.
Yes, I know it sounds stupid, but some teachers are just total cunts. Prepare for a major facepalming moment, when you ask her.

>> No.4438101

>>4438093
Not only did she ask for one solution, she asked for THE solution. Which usually means she's looking for one particular answer and you are just supposed to know which one based on the lectures or something. In this case it seems plausible that she wanted ce^x, as others said.

It is true that both op's functions are the derivatives of themselves.

>> No.4438113

why are you faggots saying that the answer is c*e^x? e^x is a perfect answer, although maybe 0 AND e^x aren't as she asked for _one_ function.

>> No.4438119

it's because women don't possess the brain power necessary for mathing

>> No.4438140

she only asked for one, you gave 2. that's like circling 2 answers on a multiple choice problem, you fuckface.

>> No.4438146

>>4438140
Both answers OP gave were correct, whereas on a multiple choice question, only one given answer is correct. It'd be more like OP circling the correct answer and then writing down an additional correct answer. It was not necessary, but it is not incorrect. Your analogy is inconsistent.

>> No.4438175

>>4438146
teacher states "give me a bag of apples".
student states "have some apples and shit."

>> No.4438176

Tell her tomorrow that she is a neckbeard for forgetting that the 0 function is a solution to any homogeneous system of differential equations.

Then sleep with her because femaths are hot.

>> No.4438177

>>4438175
It's always a laugh when average people try to create analogies

>> No.4438186
File: 64 KB, 250x250, 1330881848495.jpg [View same] [iqdb] [saucenao] [google]
4438186

>>4438177
>thinks hes superior.

>> No.4438290

I'm guessing they wanted you to write down the functions derivative as well, to show they're the same. Sounds silly but it shows you understand what's being said rather than just writing down a function (a geuss)

>> No.4438315

Does anyone else see how beautiful math is when it comes to this shit?

First off it amazed me when I found out that triangles are always using the same ratios. Given a certain angle the opp over hyp will always be the same.

But then to go further and see that the derivative of the function for opp over hype is the adj over the hyp, it's just like woah dude that's witchcraft.

>> No.4438344
File: 16 KB, 319x346, 508.jpg [View same] [iqdb] [saucenao] [google]
4438344

>>4437918
>f(x)=0 implies f(x)=x