Fundamentals of Mathematics Series Sets and Numbers, about the basic relationship of mathematical se

A subset is composed of a part of the elements of the original set, and the order of the elements is not limited.

Generally, if there is a set of n elements, there will be 2 n subsets.

0}{} empty set) has a total of 8 subsets, including the empty set and the two false subsets of itself.

And so on, the second one has 2 4 = 16.

The third has 2 5 = 32.

2 to the nth power, n refers to the number of elements in the set. So the number of subsets of these three sets is 2

to the third power, 2 to the 4th power, 2 to the 5th power.

There are empty sets of subsets of 0,1,2}, 8 of {0}{1}{2}{0,1,}{0,2}{1,2}{0,1,2}, and you can write the subsets of the other two sets yourself.

To make the formula (ax+b)(cx+d) rise above 0 to obtain the solution set a of ax+b=0.

Get the complement of solution set b with cx+d=0.

Solution (Supplement A and Supplement High Set B).

The symbol n(a) indicates the number of elements in the set a.

Able to set Chinese chess set A, Go set B, chess set C.

Known: n(a)=20, n(b)=19, n(c)=18, n(a b)=7, n(a c)=8, n(b c)=5, n(ab c)=3.

n(a∪b∪c)

n(a)+n(b)+n(c)-n(a∩b)-n(b∩c)-n(a∩c)+2*n(a∩b∩c)

43 There are 50-43 = 7 players who can't play all three kinds of chess.

x represents the element, which is the set of what you are purifying.

For example, if the vertical is preceded by (x,y), then the set is a set of points.

For example, if the sedan chair is preceded by x, it is a set of numbers.

The purpose of that vertical is to separate the representative element from the expression that follows it.

Hope it helps you o ( o haha

There is also hi me who doesn't understand, and I'm happy to answer back.

There are many ways to solve the set.、、The easiest is to draw the number line.、But because I can't insert **、、So I can't show lz the diagram I took.

As the title says, -36 is OK, but the zero boundary value should be taken into account, when a=6, {b}={x<6} The common part of a and b is the set of a, so it can.

Finally, a>=6

lz、Choose me、、、

In this kind of problem, you can first draw a number line, and enclose the shown interval in middle brackets, because the moving axis determines the interval, and you just take x less than a and lean on the known interval, as long as the two intervals are crossed, it becomes it, so it is very easy to see that a is greater than or equal to 6

First of all, a is contained in b, which means that any element in a is in b, and in this problem, x<6 must be in x or equal to 6, and the elements in a will be in b.

Draw the number line and the scaled values will be clear at a glance. a>=6, but this kind of problem, there is a place to pay attention to, that is, there is no equal sign, I hope to pay attention to the topic in the future.

First, one of the set conditions is that the elements in the set are required to be different from each other. If the value of x is not equal to 1, it is fine. Hand to hand.

Second Biling Road:

3,-2,-1/3,1/2,3,-2...Looped. According to the known conditions, it is sufficient to substitute 3 into 1+a) (1-a).

Such a question is generally a blind law in the regulatory hall. How to find patterns? Of course, some questions have to be simplified, replaced, and so on. If you can't think of an easy way to do it, you can write a finite number of terms, try it, and see if there's a pattern.

For this question, write 4 items, and there is already a loop. All elements of the set m: 3, -2, -1 3, 1 2

Hope to give advice in time.