Some simple questions about freshman math

1) The concept of natural numbers is that they are integers greater than 0, so why is the set of natural numbers equal to the set of non-negative integers and all denoted as n?

Answer: Natural numbers used to refer to positive integers, I don't know if they have changed to all non-negative integers since 90 years, I don't know where your concept of natural numbers came from, if you want to see the original concept, you can go to the elementary school math textbook. See also Encyclopedia.

2) How should the "set of all quadrilaterals" be represented? Is this descriptive?

That is, what you say is descriptive, and it can also be expressed as.

3) For the set of elements "a-b, a+b, a (squared) + b (squared)", should it be described as or should it not be bracketed?

The parentheses are the same, a-b and (a-b) represent the same element, and the three key characteristics of heterogeneity, disorder, and certainty in the middle of the set, don't drill the horns.

4) The set of "solutions of equation x(square)-3x+2=0" should be described as or.

Your expression is incorrect, and it is still expressed like this, indicating that the elements in this set are points, not numerical values, because our equation is a number after being solved, not a point, so it can be expressed in this way or directly expressed as {1,2}

5) How to answer the question "If the set a=, b=, and b is a true subset of a, find the set composed of the values of m"?

a=, b=b is a true subset of a, then b must be included in a, requiring m+1>=-2 and 2m-1<=5 The solution is {-3<=m<=3} Here also ignores a case, that is, when b is an empty set, that is, 2m-16) The mathematics stipulates that an empty set is a subset of any set, so why don't you write an empty set when using the enumeration method to describe a set?

Strange thoughts, you have to think clearly, if you use the description method, how to describe it? There is also the fact that there is no need, as an empty set, it is a special set that we prescribe, and it is very clear that a set without any elements represents an empty set, which is a description in itself.

1)."The concept of a natural number is an integer greater than 0"This concept is wrong, in higher mathematics (authority), 0 belongs to natural numbers.

So the set of natural numbers will be equal to the set of non-negative integers and will all be denoted as n.

2) should be denoted as: This representation is enumerative.

3) There is no need to put parentheses in it, because in the set, the elephants are separated by ",", so as long as there is none", it belongs to the one.

4) Neither, should be described as:

5) As long as m+1 -2 and 2m-1 5 are satisfied or b is an empty set (i.e., m+1("and=)x("and=)2m-1 is unsolved), find m.

6) An empty set is a collection, not an element in a collection.

2) Yes and no.

3) No, you don't.

4) It doesn't seem to be right, if it's 2 out of 1, choose the back.

6) An empty set is a collection, not an element in a collection.

I barely answered the score when the score was high.

Because a so a c

Because b so b c

ab is the male perpendicular line of the straight line A and B.

c perpendicular a, b, hence ab c

Big brother, in fact, what should be proven is ab c. The reason is very simple, because a, b, and ab are perpendicular to a, b, and it is easy to get ab and ab. So ab is parallel to the intersection line of and , i.e. c.

AB seems to be parallel to C......... right?

Question 1 should be wrong, why is K-2 in parentheses on the right side of the equation? Please check it out with the landlord. If the parentheses are x-2, I have the answer "Then the increment interval of the function is (1,+

2.Because the function f(x) is an odd function on r, so f(-x) = -f(x), so by .

f(-2)+f(-1)-3=f(1)+f(2)+3, f(1)+f(2)= -3

3.Since f(x)=0 has two roots, x1, x2, y=f(x) has two intersections with the x-axis, and because y=f(x) is an even function, the image of f(x)=0 is symmetrical with respect to the y-axis, so x1+x2=0

The conclusion should be parallel.

Do D A on either point over B

then ab d, ab is a surface composed of b, d.

and a , then d , d c

b, b c, so c is a surface composed of b, d.

So ab c

The first question is correct, because both the defined domain and the value range are the same as the original formula.

The second question is simple, the first one: let fx=x squared, then fx>0The second: fx = positive and negative root number 2.

Question 3: This means that if a function is to be even, then the definition domain must be satisfied with respect to y-axis symmetry. However, if a function definition domain is symmetric with respect to the y-axis, then it is not necessarily an even function.

Because the whole image, that is, the value range, also satisfies the symmetry of y. (Defining domains in relation to y-symmetry and origin symmetry is a meaning.) Can it be distance and?

I don't know what this means, but if you mean that both sides of the function image are at a distance from the y-axis, then this is possible, but it must be symmetrical to the y-axis, i.e. the two sides are equal in length from the y-axis.

It's all my hard work on my phone, so give it a point.

Solution: f(-x)=a -x-a x=-(a x-a -x)=f(x), so f(x) is an odd function when x belongs to (-1,1), and the identity can be reduced to f(1-m)<-f(1-m 2)=f(m 2-1).

And -1 1-m 1,-1 m 2-1 1 solution yields 0 m 2 (1) for f(x) to f(x)=(a x+a -x)lnaIf a 10, f(x) 0, monotonically decreasing.

Then 1-m m 2-1 is solved to -2 m 1, and joint (1) is obtained.

0 m 1 if a 10, f (x) 0, monotonically increasing.

Then 1-m m 2-1 is solved to m -2 or m 1, and the combination (1) is obtained.

1＜m＜√2

Let's talk about the idea, first of all, this function is an odd function, (you yourself replace x with -x, and find that it becomes -f(x)) Then, you only need to move the inequality to deal with it, use the properties of the odd function, remove the negative sign and put it in the parentheses, and then use the monotonicity of the function to remove f, and then solve it.

Replace. Replace x with 1-m and 1-m squared, respectively.