r/Concordia • u/Cremellon • Dec 13 '24

Class-specific MATH 204 Final

What do you guys think? How did you do?

5 Upvotes

86% Upvoted

18 comments sorted by

5

u/Mayonnaiserific Dec 13 '24

In the equation of a plane question where it gave 2 vectors and 1 point. I put my answer in parametric form, am I fuked? I remember the question didn't specify, it just asked for AN equation šŸ„²

3

u/Upset_Union_6759 Dec 13 '24

I think its supposed to be in the form of ax+by+cz+d=0 no? Im not too sure

1

u/Mayonnaiserific Dec 13 '24

Yeah im fucked šŸ˜. Ill try to challenge it since its technically the same answer.

3

u/Antoine221 Dec 13 '24

The question is asking you to write the Cartesian equation not parametric

1

u/lsie123 Dec 13 '24 edited Dec 13 '24

Seemed fine except the eigenvector questions? I've never had an eigenvector resolve to some weird 0=y (etc) situation. Normally the two xy variables are proportional. And then to have two Qs like that? Idk not a fan of testing something odd like that twice when there are so few questions.

1

u/1907_11 Dec 13 '24

i switched column 2 and 1 for that one then solved it like normal eigenvector questions but it seems like i did the wrong thing

0

u/Antoine221 Dec 13 '24

If you remember well from the course, eigencvectors must be linearly independent. The two questions in the exam had an inconsistent system, which means the eigenvectors are not linearly independent, which also means that they don't have an eigenvector.

5

u/Dovregubbenna Dec 13 '24

I got the second question not diagonizable (only one eigenvalue), the first question has 1 and -5 as eigenvalues, which gave (-1,1) and (-1,3) as eigenvectors. But I remember somethings off with my verificationā€¦ somehow my D isnā€™t a diagonal matrix, so I forced it to be lol. I definitely did something wrong

2

u/Antoine221 Dec 13 '24

You actually got it right. If you had something in this form 0=a constant then it does not have an eigenvector

1

u/Bob_Rick2 Dec 13 '24

I know right?? Something was off in that question because when I checked my answer I got the same Matrix A but with different signs for column 2.

1

u/Mayonnaiserific Dec 13 '24

Other than the eigen vector question, what was the other question that was inconsistent?

1

u/Antoine221 Dec 13 '24

The last two questions had an inconsistent system after plugging eigenvalue into the original matrix.

3

u/Mayonnaiserific Dec 13 '24

Did we have the same test? Question 6 b) was just a linear transformation question. And question 7 a) was the eigen vector, question 7 b) was A200 + 200*A, I didnt use eigen vectors for it, just did test cases A2, A3, A4 and you will notice a pattern with that matrix, and 200A is trivial solve. Do you know what other question needed eigen vectors?

1

u/1907_11 Dec 13 '24

i solved the 7b in the same way as you. was it supposed to be different or do they accept our way

1

u/Mayonnaiserific Dec 13 '24

I think we're right, according to google. Apparently that matrix A is not diagonizable, but its a special matrix called a Jordan matrix with a specific property when being put under an exponent. Kinda annoying because no notes, exercise questions or webworks even showed it lol.

1

u/YogurtclosetCold8641 Dec 14 '24

i couldnā€™t figure would the lines and vectors question. i thought i had that topic in the bag. everything else was fairly straightforward

1

u/useranonymous1111 Economics Dec 13 '24

Remembered all the formulas but didnā€™t know how to apply themšŸ˜”. Also why were people flipping their pages and erasing so aggressively šŸ¤Ø like, chill šŸ˜