Judge whether the proposition is correct, judge whether the proposition is correct, and give counter

A declarative sentence that can judge true or false is called a proposition, a correct proposition is called a true proposition, and a false proposition is called a false proposition.

That's right. Because the same number is added or subtracted from both sides of the inequality at the same time, the inequality sign does not change!

Yes, because the two sides of the inequality add or subtract the same number, and the inequality still holds.

False, true, true, false, false!

Not necessarily. It depends on whether C is positive or negative.

I think it's right, that's what I learned in school, and if I can give a counterexample, then I have to learn!

Correct fundamental properties of inequality.

This proposition must be wrong!

For example, a is a matrix of 2 3, b is a matrix of 3 2, ab is a matrix of 2 2, and ba is a matrix of 3 3. (AB and BA can't be said to be meaningless!) ）

Both are true, because the condition given by the question is the definition of the derivative, so proposition 1 is paired, and because the derivable must be continuous, so proposition 2 is also correct, and as for proposition 3 is a simplification of this limit formula, there is no problem.

A statement that makes a judgment about a matter is called a proposition. Interrogative sentences, exclamation sentences, etc., are not propositions.

1 declarative sentence.

2. Whether it is true or false.

For example: "Don't abandon, don't give up" and "Isn't an equilateral triangle an isosceles triangle?" These two sentences are propositions and the latter are not.

Do not abandon, do not give up" is a declarative sentence, and "Isn't an equilateral triangle an isosceles triangle?" It is a rhetorical question, and although the tone of the rhetorical question expresses the meaning of affirmative, it is an informal propositional concept in mathematics.

If this statement can be judged to be true or false, it can be judged to be a proposition!

Hehe, for example: we take our mother's love for us since childhood, and the teacher's teaching us. Friends help us.

In general, we have to thank them for this topic. Then we will use "Grateful Heart" as a proposition main method. Grasp the core content to the proposition.

Otherwise, a counter-example is sufficient.

i.e. suppose one of the corners is obtuse.

Yes, if the two sides are equal, then half of the corresponding sides are also equal, and the congruence of the triangle enclosed by two sides (one of which is half) and the middle line can be obtained, and the angles of the equal sides can be correspondingly equal, and then the congruence of the two triangles can be proved.

If the proposition is like this:

It is not correct to have two triangles on the second and third sides that correspond to two equal triangles.

The proposition is correct. The middle line divides the third edge from the midpoint, and the other two sides are equal, so the other two points that intersect on those two sides are connected. To draw the middle line, to make the two sides equal, the triangle must be congruent.

Experts also ask questions? That's right!

(1) Correct.

2) Correct, provided that in plane geometry, if it is in space geometry, it is not true, and two disjoint straight lines can be different faces.

3) Error, (-5) >3, -5<3

1.That's right.

2.Wrong. to be in the same plane.

3.Wrong. x is -3 and y is -2

The first one is correct.

The second is correct.

The third incorrect reason (-2) 1 -2 1

1. Wrong, three-dimensional space.

2. Wrong, within the same plane.

3, error x=(-15), y=14

In plane geometry, (1) and (2) are correct, and in solid geometry, two straight lines can be on opposite surfaces. (3) Incorrect, such as:

6) 2>2 2, and -6<2.

False Any obtuse angle 2 ?? Didn't finish it? 1) False. In two cases, the angle of one term is equal to the complementarity or complementarity. Both are false propositions. Here are some examples: 1. When an angle is 90 degrees, it is on the same side.

1, True 2, False 3, False 4, True 5, True 6, False 7, False 8, True.

1.Right. 2 false.

3 False. 4 pairs.

5 pairs. 6 False.

7 false. 8 seems to be less conditional.