Discrete math problem

[Tayeeba]

I understand number 2, but not 3 . Why the sign(marked) is different at 3? Can anyone please explain?


[also, I understand my class lecture, do assignments and practice (just from example problems,though in exam we get exercise problems ), but in exam I cannot answer properly, even I mess up simple things during math exam even though I know the basic idea. What should I do? Any suggestion?]

 

[Otis]

I understand number 2, but not 3. Why the sign(marked) is different at 3?

It's better to use the word "symbol" instead of "sign" because sign means positive (+), negative (-), or neither (0).

In 2, those are subset symbols.

In 3, they are superset symbols.

For example, 2 says that set A₁ is a subset of set A₂. In other words, set A₂ contains set A₁.

In 3, they say that set A₁ is a superset of set A₂. In other words, set A₁ contains set A₂.

I am not familiar with the union and intersection notation used, so the exercise statement is hard for me to interpret.

 

[Tayeeba]

It's better to use the word "symbol" instead of "sign" because sign means positive (+), negative (-), or neither (0).

In 2, those are subset symbols.

In 3, they are superset symbols.

For example, 2 says that set A₁ is a subset of set A₂. In other words, set A₂ contains set A₁.

In 3, they say that set A₁ is a superset of set A₂. In other words, set A₁ contains set A₂.

I am not familiar with the union and intersection notation used, so the exercise statement is hard for me to interpret.

Thank you for your explanation, the idea of superset totally makes sense.
Also, thanks for correcting me, will remember in future.

 

[mmm4444bot]

I understand my class lecture, do assignments and practice (just from example problems, though in exam we get exercise problems), but in exam I cannot answer properly, even I mess up simple things during math exam even though I know the basic idea. What should I do? Any suggestion?

This sounds like you just need more practice. When I was in school, I kept doing extra exercises (many different kinds) until I felt very confident that I would recognize what to do on the test questions, and this extra practice reduced the number of silly mistakes on my exams because I had already made most of them while practicing. Double-checking steps as you go, on an exam, can also help eliminate minor mistakes like arithmetic goofs.

When you say that you practice "just from example problems", you're not talking about only worked examples, right? Students need most of their practice from exercises that don't come with "hints" and exercises that require thinking from a different perspective than the way shown in worked examples.

If the exam exercises seem different from what you've practiced, then maybe you haven't been exposed to enough variety of practice questions.

You could contact your instruction with these concerns, also. See what they suggest.

 

[Tayeeba]

This sounds like you just need more practice. When I was in school, I kept doing extra exercises (many different kinds) until I felt very confident that I would recognize what to do on the test questions, and this extra practice reduced the number of silly mistakes on my exams because I had already made most of them while practicing. Double-checking steps as you go, on an exam, can also help eliminate minor mistakes like arithmetic goofs.

When you say that you practice "just from example problems", you're not talking about only worked examples, right? Students need most of their practice from exercises that don't come with "hints" and exercises that require thinking from a different perspective than the way shown in worked examples.

If the exam exercises seem different from what you've practiced, then maybe you haven't been exposed to enough variety of practice questions.

You could contact your instruction with these concerns, also. See what they suggest.

Thank you so much, I got your point, and yes I need lot more practice from exercises without any hints.
Your every word is so helpful for me. Thanks again for sharing your strategy. I am going to follow the same.
Have a very nice day!