I think my Maths is getting worse

To everyone who reads this post, you. Yes, nobody else, it's you.
Please answer the question and leave me a comment.
I need it URGENTLY.


So which of the following region represents the region of B\A' ?



My answer is (i).

But my maths lecturer said it's (ii).

I was stunned.



I used to have a lot of confidence in my Maths.

Even sometimes when I'm wrong, I will still argue with you like nobody's business, claiming that I'm right, until someone can prove me it's wrong, or at least, convince me.

But today, I hesitated.

I didn't argue with the lecturer.

The lecturer said (i) is wrong, and told us B\A' is that we need to remove the common part of both sets and add up all the remainings, so (ii) should be the answer.

I remained sceptical.

I wanted to argue about it, but I hesitated.

I began to doubt if I'm right.




"Sets, Relations & Functions."

The very first chapter which we have learned in junior middle one.

"How easy this chapter is!", I thought.

Yea, it's because I used to score full marks in that particular subject in the olden days.

I even laughed when I saw this chapter being included in the syllabus of my current Maths subject, namely "Numerical Method and Logic".



But now, I hesitated. Why?

Why did I hesitate?



I was once so proud of myself that I even challenged Mr. LMH (the best Maths teacher I've ever seen) with this paradoxical question, 1-2+3-4.... , which I said the answer is 1/4 , but he said it's not.

(No, actually my intention was to know his answer for that question since it's a paradoxical equation. But at least I did dare to ask.)

I then argued with him and asked him to check the website http://en.wikipedia.org/wiki/1_%E2%88%92_2_%2B_3_%E2%88%92_4_%2B_%C2%B7_%C2%B7_%C2%B7 , as there are quite a number of ways proving that 1 - 2 + 3 - 4 + ... = 1/4



But yeah, he's much more stubborn than me. He did not even bother to check, and without hesitation, he told me again he will never be wrong and added that the website is completely a nonsense.

Haha! So that's mathematician's spirit!

I liked that, though I was a bit offended.




But this time, this time.

I hesitated.

Not because of what, but because I doubted..





Please leave me a comment. I need your answer.

Thanks in advance.