Current location - Training Enrollment Network - Mathematics courses - [Urgent] Please ask the master to answer several necessary questions about set in high school mathematics, and work them out before three o'clock, and add extra points to the detailed intercom as appr
[Urgent] Please ask the master to answer several necessary questions about set in high school mathematics, and work them out before three o'clock, and add extra points to the detailed intercom as appr
[Urgent] Please ask the master to answer several necessary questions about set in high school mathematics, and work them out before three o'clock, and add extra points to the detailed intercom as appropriate. a≤ 1;

A= 1/3 or-1/2 or 0; (Pay special attention to the case of a=0, an empty set is a subset of any set)

0;

m;

Solution: according to (CuA)∩B={2}, A∩(CuB)={4}

It is known that 2 is an element of set B and 4 is an element of set A; And 2 is not an element of set A, and 4 is not an element of set B.

Substitute 4 and 2 into set A\B to get the equation:

16+4a+ 12b=0

4-2a+b=0

Get: a=8/7 b=- 12/7.

Solution: According to the meaning of the question, x 2-4mx+2m+6 = 0 has at least one solution less than 0.

△ = 16m 2-4 (2m+6) ≥ 0m ≥ 3/2 or m≤- 1.

x 1=2m+√(4m^2-2m-6)x2=2m-√(4m^2-2m-6)

Obviously x2≤x 1

So there are: 2m-√ (4m 2-2m-6)

When m≥3/2, solve the above formula to get: m.

When m≤- 1, the above formula holds.

To sum up: m≤- 1

Solution: b: x 2-5x+6 = 0x = 2 or x=3.

C: x 2+2x-8 = 0x = 2 or x=-4.

B∩C={2}=A∩B

That is, 2 is an element of the set A. If it is substituted into the equation, it is: a 2+2a+15 = 0.

No solution! ! ! The landlord must have copied the equation of group A wrong. I estimate that the topic is a = {x | x 2-ax+a 2- 19 = 0}.

Solution: Suppose there are X netizens who agree with A and B, and x/3+ 10 netizens who disagree with A and B.

The number of people in favor of A =500*3/5=300; the number of people who disapprove of A =200.

Number of people in favor of B =300+30=330 Number of people who disapprove of B 170

So: the number of people who only agree with A =300-x, and the number of people who only agree with B = 330-x.

The number of people who disapprove of both A and B = 500-(300-x+330-x+x) = x-130.

So there are: x-130 = x/3+10x = 210.

A: There are 2 10 netizens who agree with A and B, and 80 netizens who disagree with A and B..