Some advice. should I contest some of this grading?

[Anonymous No.2155257]

I recently took a Linear Algebra exam which was quite easy. I feel like I knew the material, however, my biggest problem is how to formalize these answers properly. So before I go to the teacher and act like a whiny bitch about grading I just want some other opinions for if you personally and truthfully believe I deserved more points than I got.

And I want honest opinions which I expect from the internet. Don't hide criticism.

These are the official solutions:
http://www.math.wsu.edu/math/faculty/tsat/teach/files/420/mII420_solutions.pdf

These are the questions I am asking about plus my answers for each:

Problem 2 part (a)
http://img259.imageshack.us/i/problem2parta.jpg/

I believe that the only mistake I made here was a single algebra mistake and I agree with the grade I got here. -1 point for this sort of error seems fair.

Problem 2 part (b)
http://img440.imageshack.us/i/problem2partb.jpg/
Here the same algebra mistake in part 1 ends up costing me 2 of the 5 total points in part (b).

[Anonymous No.2155261]

Problem 2 part (c)
http://img227.imageshack.us/i/problem2partc.jpg/
This is where I start to get a little annoyed. Again, the same single algebra mistake from part (a) costs me another 2 points in this section.

So in total I lost 5 points for a single error, costing me 12.5% of my total grade for the exam.

Problem 3 part (a)
http://img813.imageshack.us/i/problem3parta.jpg/
Missed full 5 points although I feel my informal definition was almost identical. I should lose some points for the informal nature, but should I lose all of them?

Problem 3 part (c)
http://img444.imageshack.us/i/problem3partc.jpg/
Here I tried to show it was true by showing that the opposite case is false. Thus the original case would be shown true. I think most of the points lost here are valid but I feel -4 of the total 5 may be a bit much.

I don't want to sound bitchy and I'm content with the grade I got. I'm just looking for some alternative opinions to see if others feel I ask the teacher about the grading.

[Anonymous No.2155291]

Grader right. You're wrong.

DEAL WITH IT

[Anonymous No.2155334]

Stop whining you damn premed. Your grade was probably consistent with how he did the rest of the class. Accept that if your answer is wrong, points will be docked, and nobody is going to painstakingly go through your work to see how many steps were valid and how many weren't. You may have gotten unlucky, but it will all average out in the end.

[Anonymous No.2155358]

The "get tough lol" speech is pretty tired. And unless you actually look at what I present rather than reading the subject line and respond, than I won't bother to take your opinions into consideration since I've already considered these obvious points.

[Anonymous No.2155381]

You could have probably recovered points on (b) if you had noted that "These vectors are OBVIOUSLY not orthogonal, fuck I must have made a stupid algebra mistake."

[Anonymous No.2155383]

*Usually* professors will mark the initial error and then continue on using the assumption of your error, as long as its reasonable.

In this case the professor didn't. If its his policy then tough shit, its his prerogative.

Otherwise the grader may have just been following the rubrik. Typically in my large classes the graders just follow the rubrik and you can then bring up any questions for regrading. So you can ask the prof/ta if they would regrade the test considering the initial mistake you made. If the prof is reasonable he probably would do it.

[Anonymous No.2155396]

>>2155261
> Problem 3 part (a)

Your definition is completely wrong. You missed the whole point:

y is in the orthogonal complement of W if and only if y is orthogonal to EVERY vector in W. (That is if <y,x> = 0 for ALL x in W).

Your definition requires only that y be orthogonal to SOME x in W. This shows a deep lack of understanding of the concept. For let V = R^3 and let W be the space spanned by the vectors {x1 = (1,0,0), x2 = (0,1,0)}

x1 is in W and <x1,x2> = 0 but x2 is NOT in the orthogonal complement of W.

[Anonymous No.2155402]

>>2155396
I didn't read the other ones since they were tl;dr. But given your track record so far, I am going to guess that the grader is correct on the other ones too.

[Anonymous No.2155415]

After reading the problems and your solutions I honestly don't know why you only lost 3 points or whatever. Most of your errors are beyond any justification and even show (as was already mentioned) a profound misunderstanding of vector spaces.

TL;DR - you deserve to have more points knocked off.

[Anonymous No.2155427]

>y is in the orthogonal complement of W if and only if y is orthogonal to EVERY vector in W. (That is if <y,x> = 0 for ALL x in W).

>Your definition requires only that y be orthogonal to SOME x in W. This shows a deep lack of understanding of the concept. For let V = R^3 and let W be the space spanned by the vectors {x1 = (1,0,0), x2 = (0,1,0)}

No my definition states for every x in W there is some y in W-pert such that <x,y>=0. That is, that the y vector is orthogonal to EVERY X in W.

The error here is obviously one of miscommunication not mis-understanding of the concept.

[Anonymous No.2155434]

>>2155415

again this overly dramatic rabble is beyond boring. But not unexpected from 4chan.

[Anonymous No.2155439]

>>2155334 here,
After reading through everything, I think:
(2b) Deserves points docked due to your failure to spot the error regardless of whether it was due to a propagated mistake
(2c) First equation you write down is wrong, assumes unit vectors
(3a) Your definition is not identical, it is wrong
(3c) What the hell are you doing?

[Anonymous No.2155440]

>>2155427

Well, considering two people in independent cases misinterpreted your answer, perhaps your presentation needs some work so there won't be so much miscommunication.

[Anonymous No.2155455]

>>2155427
>No my definition states for every x in W there is some y in W-pert such that <x,y>=0.
>That is, that the y vector is orthogonal to EVERY X in W.
Those two statements are not the same at all.

[Anonymous No.2155456]

>OP felt he studied well enough for the test
>Makes some mistakes
>Got poor grade because prof grades harshly
>Upset, feels like wasted time studying
It happens.

Also, the less wordy you are in your posts, the more likely people are to read them. And don't be sound whiny about it. If you think it's very unfair, say something to prof or rage about it here, don't be all like "hey... I think I didn't deserve as many points as I got off for this minor blah blah blah".

[Anonymous No.2155457]

>>2155434

It's not overly dramatic at all. I'm a teaching assistant in a university mathematics department and I see things like this all the time. Consider yourself lucky that you don't have me grading your papers. When the kids in my discrete mathematics class mess up definitions in their homework and work a problem wrong assuming said definition, I start off docking half their points, more get dropped if they make other ridiculous assumptions. I also tend to knock points off when people just start writing down equations without any explanation as to their purpose (unless those equations are precisely what's needed which in 90% of cases is not true.)

[Anonymous No.2155462]

>>2155455
This man is right, they're very different.
I've taken multiple classes in linear algebra, as well as a class in abstract algebra.

[Anonymous No.2155482]

>>2155455 again,
I can see how this could be a failure to communicate, but you should be able to understand and write quantifiers in natural language by now. Brushing this off as a failure to communicate is like whining that you didn't understand the professor's 2's because you thought that numeral represented three.

[Anonymous No.2155503]

And on another note: We don't really have to read your answers (although I did) to see you are being overly whiny. You admit your answers are wrong and are whining that you weren't given sufficient partial credit. Your graders don't have to give you any partial credit at all.

[Anonymous No.2155542]

>And on another note: We don't really have to read your answers (although I did) to see you are being overly whiny. You admit your answers are wrong and are whining that you weren't given sufficient partial credit. Your graders don't have to give you any partial credit at all.

I do not care about your opinions of me or my character as a person. Granted, posting this in 4chan which is full of overly emotional teenagers who feel the need to act tough and be special isn't the best way to get feedback without useless bullshit. It was worth a try anyway and there was some decent feedback here if you can cut out the retarded superiority complexes and ad-hominids.

[Anonymous No.2155551]

>>2155542

>And I want honest opinions which I expect from the internet. Don't hide criticism.

/thread.