If you are good at math, let s take a look at what is good at math?

I used to make calculation mistakes all the time, which means that although I had a good brain when I did the questions, I didn't have a good mentality, I was either too nervous, or I was too impatient, or I didn't do it seriously from start to finish. Such a bad problem must be corrected in time, otherwise it will be difficult to get rid of the habit.

It's actually easy to change, usually complete every question carefully, don't think you think you know how to finish it or make a mistake and don't take it seriously. And don't do your homework with others for the answers, and you can't get the answers right if you don't check them.

When you take the exam, you should have a good mentality, don't be too nervous and don't try to be fast, you want to finish it first and then go back to check, often you don't have this time, and it is difficult to check it out if you have time. Therefore, we must strive to get it right the first time, ensure the correct rate, and do not panic if we do so.

Just do more questions!

But it's going to take a lot of work!

Hehe, it's not much different from me.

Do more. Don't think about anything else, just calm down and write slowly, if you have time.

Inspections are important.

40 divided by 5 equals 8, 8 is the median of these 5 numbers, so it is 2) (3*6+2*8) divided by 5, equals.

Not in the third question.

Sorry, I can't help you!

*8-36=4, 5*8 is the sum of 5 numbers, 36 is the sum of 4 numbers, then the remaining numbers are subtracted.

2. (3*6+2*8) 5=, 3*6 is the sum of the first 3 numbers, 2*8 is the sum of the last 2 numbers, and their addition is the sum of 5 numbers.

3、（x1+x2+..xn）/n=x

So x1+x2+..xn=x*n

Then 2+x1+2+x2+...2+xn=2^n+（x1+x2+..xn）=2^n+x*n

If you don't understand, I'll be clear.

Average + Number = Total.

5 times 8 = 40

Total = Sum of 5 numbers.

Total number - sum of 4 numbers = remaining number = 40-36 = 4 total = average number + number of numbers, 6 times 3 = 18

2 times 8 = 16

Total = 18 + 16 = 34

34 divided by 5=

The above is all clear.

Thank you. o(∩_o

Find more topics to contact.

When you encounter something difficult to calculate, don't think about relying on a calculator.

Observant... You have to be careful.

I also often get the topic wrong because of carelessness.

It's going to get better.

As long as you know how to multiply formulas, you can carry.

Being able to calculate is not enough proficiency, practice makes perfect, practice more. Certain.

At that time, I made a thick Ka roll and practiced it, and set a good time for myself, and during this time, I could make as many rolls as I did less or wrong, and I was practiced by my father for a week, and I changed this problem.

This is the sine theorem of triangles.

This is the sinusoidal formula for solving the triangle, and 2r is twice the radius of the circumscribed circle of the triangle solved.

90x(40%-20%）+90=108

Analysis process: 40%-20%=20% is that Lanlan collects 20% more than Honghong, 90x20% (this 20% is made above), this result is 20% more = 18 photos.

18 + 90 = 108, the result is 20% more, that is, 18 cards + the original red 90 cards = 108 cards, which is Lanlan's.

There is also a way to use:

Lanlan is 40%-20%=20% more than Honghong

90 divided by 100x20 + 90 = 108 (90 divided by 100 to get one hundredth, multiplied by the extra 20 percent of the number of sheets, and finally add 90 is the number of Lanlan.

Suppose that x sheets are collected, then the red and red collections can be expressed in this way (1+20%)*x=90, and the answer to the solution is x=75, and then the number of Lanlan's collection is (1+40%)*75=105, so the number of Lanlan's collection should be 105 stamps.

Red red: Ming Ming = (1 + 20%): 1 = 6: 5 = 18:15 Lan Lan: Ming Ming = 1: (1-40%) = 5: 3 = 25:15 Per serving: 90 18 = 5 (sheets).

Lan Lan collected: 5x25 = 125 (sheets).

Solution: She has collected x stamps.

x(1+.)

The solution is x=75

Shelan collected Y stamps.

Derived from the meaning of the title (

The solution is y=125

A: Lan Lan has collected 125 stamps.

Obviously collected 90-90*20%=72 sheets, Lan Lan collected 72+72*40%=, about 101 sheets.

Equation? Shelan Lan has x sheets.

x+140%-20%=90

Formula? 90 + 120%-40% = self-calculation.

Let A have 3x kg and B have 2x kg.

3x-10=2x+10x=20

Because the function passes the origin, substituting (0,0) gives the derivative of b = 0 f(x) = 3x square + 2 (1-a) x - (a square + 2a) When x = 0, the derivative = - (a + 2a) = -3

So a = 1 or -3

b=0;a=1/a=-3.

First, substituting (0,0) into the analytic formula yields b=0;After that, the derivative is obtained analytically, and f is obtained'(x)=x 3+(1-a)x 2-a(a+2)x, substituting (0,-3) to get a