For the first year of inequality, describe the following equations in language 30

2. Clever unknowns. Several quantities can be set as unknown in a worksheet, but which one is easier should be carefully considered. For example:

The ratio of the velocity of A and B is 3:2, and when finding the velocity of A and B, we can let the speed of A be a kilometer hour and B be b kilometers and hour, which is a system of binary linear equations; Or let the velocity of A be a kilometer-hour, then B is 2 3a kilometer-hour, so that although it is a one-dimensional equation, there are fractions; Or let A have a speed of 3a kilometers per hour and B a speed of 2a kilometers per hour.

It can be seen that the last one tries to be the best. Unknowns are set according to different topics.

3. List equations according to the equiquantity relationship.

4. Solve equations. At this time, we may encounter two unknowns, and we can only list one equation, we need to see if there are still implicit conditions, such as the number of people and the number of objects, all of which must be positive integers, which are implicit conditions, especially in inequality equations. There is also the need to test the root of fractional equations.

5. Write down the unit and answer. This step is often overlooked, but in fact, it is a reflection of whether you have read the question, whether you know what the question requires, and whether you have to stand for marks in the exam.

6. Practice diligently, practice makes perfect. Touching the analogy bypass, drawing inferences from one another.

This is a little bit of my personal experience in docking application problems, I hope it will be helpful to you.

This is the problem of variable signs in inequalities, and the so-called change of signs, the two sides of the inequality are divided by a negative number at the same time (simultaneous change of signs), which can be used as a conclusion.

So the answer to this question is:

It should be an inequality variant, so 1-a<0

a>1

It is clear that the unequal sign has changed direction.

Then 1-a<0

a>1

One side parallel to the wall cannot be without, so the sum of the other two sides cannot be greater than or equal to 202x-1<20x<

At the same time, the side parallel to the wall cannot go beyond the range of the wall.

2x-1 >=12 x>=

In summary, <=x<

1.The length of the fence parallel to the edge of the wall is 20-x-(x-1)<=8 and 20-x-(x-1)>0

2.Leave a wooden door 1 m wide perpendicular to the side of the wall x - 1>0 long

In summary, <=x<

Solve inequality {basis}

Solve the group of inequalities {basic} remember the formula Same as big takes the big, the same small takes the small, and the big takes the middle. Bigger than the big one, smaller than the small one, there is no solution.

Use a number line to represent the solution set {must be done every exam, just to be on the safe side}

Inequality application problems {engineering, itinerary, etc. will be discarded here.} There will be new types of questions, the main ones being shopping to save money, and the problem of program design. ｝

The application questions for the inequality group { are the same as above, but the difficulty will be deeper. And some of the questions will be very difficult. ｝

Inequalities containing letters, known solution sets, and the value of the letters. {This is a very scary test center, and it is also a score killer for students in the first year of junior high school, and it is also the most difficult part of the first year of junior high school, so it is better to study hard here, because the second year of junior high school will continue to study this problem.} Get the groundwork right. ｝

Inequality. It is based on equations, and the idea of equations is basically the same, but it faces the consideration of unequal relations, some obvious and some hidden. Be sure to read and make full use of the known conditions.

Learning inequalities well is very helpful in life.

The same big takes the big, the same small takes the small, the big takes the middle, and the contradiction is unsolvable.

20x+8=12y+4

150 "Number of 250, meet 20x+8 has 168,188,208,228,248

Meet 12y+4 have 160, 172, 184, 196, 208, 220, 232, 244

Therefore, it is 208 people.

From the meaning of the title, it can be seen that the number of people satisfies 20x+8=12y+4

150 "Number of 250, meet 20x+8 has 168,188,208,228,248

Meet 12y+4 have 160, 172, 184, 196, 208, 220, 232, 244

Therefore, it is 208 people.

Hello: (1) From -2x 6, get x -3

The answer is based on the basic property of inequalities3: when both sides of an inequality are multiplied (or divided) by the same negative number or equation (less than 0), the direction of the inequality sign changes;

2) From 3x 2x-4, get x -4

The answer is based on the basic properties of inequalities1: the same number or formula is added (or subtracted) to both sides of the inequality at the same time, and the direction of the inequality sign does not change;

Good luck with your studies!

1. Both sides of the inequality are divided by the same negative number at the same time, and the direction of the inequality sign changes.

2. Add or subtract the same integer on both sides of the inequality at the same time, and the direction of the inequality sign remains unchanged.

(1) The two sides of the inequality are divided by the same negative number (-2), and the direction of the inequality sign changes;

2) Add the same negative number (-2x) to both sides of the inequality, and the direction of the inequality sign does not change.

(1) When both sides of the inequality are multiplied by (-1 2) at the same time, the direction of the inequality sign changes.

2) Add (-2x) on both sides of the inequality at the same time, and the direction of the inequality sign does not change.

(1) Inequality property 3 (2) Inequality property 1

I was wrong, it should be (-9) (4)!

Solution: (2m-n) x 4n-3m

From (2m-n)x+3m-4n 0 to x 9 4, the sign of the inequality changes, so that (2m-n) 0

Because (4n-3m) (2m-n)=(9) (4)

The available relation: 4n-3m=-9

2m-n =-4

Solution, gets: m=-5, n=-6

Substituting the result into (m-4n)x+2m-3n 0, yields.

5+24）x-10+18＞0，19x ＞-8x ＞-8/19

The solution is x>9 4, indicating 2m-n<0

Yes: (4n-3m) (2m-n)=-9 4 gets: m=-7n 6

Bring in the solution: x<32 31

LZ is looking to see if the topic is correct, I'll change it.