Round 3 answers:

1. D
2. D
3. B
4. A
5. B
6. C
7. D
8. D
9. A
10. A
11. A
12. C
13. B
14. D
15. C
16. A
17. D
18. B
19. A
20. C

1-D
2-D
3-B
4-A
5-B
6-C
7-D
8-D
9-A
10-A
11-A
12-C
13-B
14-D
15-C
16-A
17-D
18-B
19-A
20-C

Fuck you to hell, matrices. To. Hell. I sincerely hope whatever is next is something simpler, like multidimensional calculus.

1. D
2. D
3. B
4. A
5. B
6. C
7. D
8. D
9. A
10. A
11. A
12. C
13. B
14. D
15. C
16. A
17. D
18. B
19. A
20. C

Edited because I apparently can't tell the difference between typing "A" and "B", no matter what my paper says.

1. D
2. D
3. B
4. A
5. B
6. C
7. D
8. D
9. A
10. A
11. A
12. C
13. A
14. D
15. C
16. A
17. D
18. B
19: A
20: C
Technically, matrices ARE easier than calculus because most matrix equations are built to be linear.

Well, i'm not sure about what happened on the last two pages, but let me try this round:

1- D
2- D
3- B
4- A
5- B
6- C
7- D
8- D
9- A
10- A
11- A
12- C
13- B
14- D
15- C
16- A
17- D
18- B
19- A
20- C

Could you check how many entries share your answer, and report that to me?

wot?
So, i was just in line?
... better than late, i guess.... ;p

My post: 107

Other posts:
105 - matched
106 - has A for #12.
108 - matched
109 - matched
110 - has A for #13.
111 - matched

Actually one of those I had guessed at since my numbers were acting a little goofy, but I changed it when the numbers I did get pointed to only one possible answer. So I've only got the one different answer now.

Thanks for pointing that out. You ninja'd me while I was looking everything over.
I've changed the post to reflect that.

13) ad - bc = (-18) - (12) =-18 -12 = -30

I'm very, very tired right now and need at least a nap...
later?

12 -> the only wrong for me... but i've used this formula
->

http://upload.wikimedia.org/wikipedia/it/math/1/d/a/1da9160abd8579b4dc92cee3c6cece62.png

, so i guess i made an error in the calculation

13 -> -18 * 1 - (4*3) = -18 - 12 = -30

Thats fine :)

12-
14*(8*5 - -1*-2) - 3*(-13*5 - 0*-2) + -10*(-13*-1 - 8*0)=597