Ask a difficult math problem, ask a very difficult math problem

Freezing three feet, not a day's cold. Learning is a gradual process, and it is not possible to "make leaps and bounds". It is necessary to study hard and accumulate slowly, so that quantitative changes can cause qualitative changes.

The only things I can say are the very old-fashioned ones: listen carefully in class, do a good job of pre-study and review, complete homework carefully, and ask more questions if you don't understand. In short, first of all, correct the attitude; secondly, work towards your goals; That's how we can make progress.

Without it, only the hand is familiar.

1.Skilled. 2.Overcome your fears.

3.Right of way.

4.If there is any question, please come to Baidu in time to know and ask.

Do more questions, summarize more, and never sleep in class.

Problem solving method + more practice.

It's best to find a beautiful classmate to study with.

Listen carefully in class, practice more at home, and don't think too complicated.

Problem solving method + more practice.

Practice more, there are not many shortcuts.

I have to do more questions, ask more questions, this is my experience!!

How to make your IQ grow by leaps and bounds lz do you know I don't know.

If the number of single digits is 2x, then the number of 19 digits is 10x

The number z can be expressed as 10x+2x

If you swap the number in the single digit with the number in the ten digit.

This number is expressed as 20x+x

then (20x+x)-(10x+2x)=36

21x-12x=36

9x=36x=4

After bringing it in, it came to be 48

The number on the single digit is 2 times the number on the ten digit, indicating that the number on the single digit is an even number, if the single digit is exchanged with the number on the ten digit, the new number obtained is 36 larger than the original number, that is, even number - a number = even number, indicating that the number on the ten digit is also an even number, and only 4 can be taken

The single digit is 2*4=8

This number is 48

According to the meaning of the title, you can know that this set is.

From this, we can see that there will be n numbers in the nth row, and the last one is 1+2+...n)

The first one is:

1+2+..n-1)

1, so the fifteenth row of the first trace of a number is

1=106, the last one is

So the 15th in the 4th row is

4=109, m in the nth row is

1+2+..n-1)+m=n(n-1) 2+m2n+1 is the first in row

1+2+..2n)+1, and the last one in the 2n+1 row is slow.

1+2+..2n+1), the average of the two is the middle:

n(2n+1)+1+(n+1)(2n+1)

All possibilities are 6x5x4x3x2x1=720 and the probability of not disturbing is 2x2x2x2x1=32

Only the first person will not disturb the other students when they hand in the paper, so p=5 6

2 3, sit on both sides and do not affect others.

Speed = distance time.

The total distance is the sum of the round-trip distance, that is, the total distance is 2

Departure time: 1 100

On return: 1 60

The total round trip time is 1 100 + 1 60 = 2 75, so the average speed is 2 (2 75) = 75 km/h.

There is a formula for round-trip speed: vaverage = 2 v1 v2 v1 + v2

2 60 100 60 + 100 = 12000 160 = 75 kmh.

Speed = distance time.

The distance from A to B is S km, so the car drove 2Skm;

The opening time is (s 100 + s 60) hours;

So the average speed is 2s (s 100 + s 60), i.e. 2 (1 100 + 1 60) = 75 kmh.

If the distance is regarded as 1, the time taken to drive from A to B is 1 100, and the time taken to drive from B to A is 1 60, and the total time (1 100 + 1 60) is 1 + 1 = 2, so the average speed is 2 (1 100 + 1 60), that is, 75 km h.