Mathematics. Formula. Good plus points !!

Length unit conversion.

1 km = 1000 m 1 m = 10 decimetres.

1 dm = 10 cm 1 m = 100 cm.

1 cm = 10 mm.

Area Unit Conversion.

1 square kilometre = 100 hectares.

1 hectare = 10,000 square meters.

1 square meter = 100 square decimeters.

1 square decimeter = 100 square centimeters.

1 square centimeter = 100 square millimeters.

Volume (volume) unit conversion.

1 cubic meter = 1000 cubic decimeters.

1 cubic decimeter = 1000 cubic centimeters.

1 cubic decimeter = 1 liter.

1 cubic centimeter = 1 milliliter.

1 cubic meter = 1000 liters.

Weight unit conversion.

1 ton=1000 kg.

1 kg = 1000 grams.

1 kg = 1 kg.

RMB unit conversion.

1 yuan = 10 jiao.

1 jiao = 10 points.

1 yuan = 100 points.

Time unit conversion.

1 century = 100 years 1 year = 12 months.

The big month (31 days) has: 1 3 5 7 8 10 December and the small month (30 days) has: 4 6 9 November.

28 days in a common year and 29 days in a leap year.

There are 365 days in a normal year and 366 days in a leap year.

1 day = 24 hours 1 hour = 60 minutes.

1 minute = 60 seconds 1 hour = 3600 seconds. Hope.

a+b=b+a

ab=baa+b+c=a+(b+c)

a(b+c)=ab+ac

a|=a(a is greater than or equal to).

a|=-a(a<0)

...... to the apex angles equallyHope.

Khan, the first floor is already very detailed.

1.Set to win x field, draw y field, x+y=8, 3x+u=18, get x=5, y=3

2.Let poplar x, fir y, (x+y) 2+56=x, (x+y) 3-14=y, and get x=182, y=70

1 Maintaining an unbeaten record shows that there is no third case, which is still a pika cage problem:

If the total win is 8x3 = 24 points (24-18) (3-1) = 3 games are a draw, 2 cedar trees should be 56 lessons less than half of the total, so the score difference is 1 2-1 3 = 1 6 The difference in the number of trees is 56-14 = 42

42 1 6 = 252 for a total of 182 and 70 trees.

1.Since the team is undefeated, set up to win x games, draw y games, and have x+y=8; 3x+y=18.。You can solve it, and you get x=5, y=3. So 5 wins, 3 draws.

2.The same equation is used to solve, let the poplar tree x tree and the fir tree y tree. Then there is: x-(x+y) 2=56;y-（x+y）/3=14。

solution, get x=182, y=70Therefore, there are 182 poplar trees and 70 fir trees.

1.Because it is undefeated, there are only two unknowns, win x game, draw y field, and have x+y=8; 3x+y=18.。

x=8-y,3(8-y)+y=18

Yields: x=5, y=3. 5 wins, 3 draws.

2.Set up x poplars and y cedars. Then there is: x-(x+y) 2=56;y-（x+y）/3=14。

x=2y+42,2y+42-(2y+42+y)=56 yields: x=182,y=70There are 182 poplar trees and 70 fir trees.

One: x+3y=18....x+y=8 gives a win, 5, draw, and 3.

Two: Poplar 210 shirt tree 98

Let this number be x

5（4（5x+6）+9）= 100x + 165 = 100（x+1） +65

Since x+1 is an integer 100 (x+1) ten digits and unit digits are zero, so just remove the last two digits (56) of mom's number and subtract 1 to make x.

For example 198165 removing two digits from 1981 and subtracting one equals 1980

Solution: (1) Subtract the number by 165 and divide it by 100

2) Let the number that my mother want to say be a, and the calculated number is b5*(4(5a+6)+9)=b

20(5a+6)+45=b

100a+120+45=b

100a+165=b

a=(b-165)/100

A....Welcome to it!

Subtract 165 from the number and divide it by 100, and let this number be x, and you get the formula.

5x+6)*4+9]*5=Score.

then the equation on the left = 100x+165

Very simple question, let this number be x, through these operations, you can finally find out that the number my mother said is actually 100x 165, that is, to solve an equation about x, and this number is generally not too complicated so I can get the answer faster, if I say this number is, can I get the answer faster?

1.It is the reduction method. 《(3765÷5-9）÷4-6》÷5=36 2.

Rewind the known number and change the symbol. For example, 3765 is a known number, the last step is 5, and in the reduction method, 5

Revert all the way to the first step. Have you learned?

Draw a standard.

Copy charts will be better to analyze o(o

Connect the OD OE

ab cut circle baio in d, duac cut circle o in e ode = oea=90°

zhi a=90°

The quadrilateral aeod is rectangular.

DAO again do=eo

The rectangular aeod is square.

Let od=ad=r

AC parallel od

ABC is similar to DBO

ac/od=ab/db

i.e. b r = a a-r

ar=ba-br

r=ab/(a+b)

r=a*b/(a+b)

Process connection OA

s△abc=s△aob+s△aoc

Because ab, ac and circle o are tangent.

So a*b 2 = a*r 2 + b*r 2

r=a*b/(a+b)

1 All (1) 5x+

5x=5x=27

x=27/5

2)x-2/5x=4/7

1-2/5)x=4/7

3/5)x=4/7

x=(4/7)/(3/5)

x=20/21

3)25x÷2=475

25x=2*475

25x=950

x=384)3/4x-1/2x=114

3/4-1/2)x=114

1/4)x=114

x=114*4

x=4565)x=

6)2/7x+3/8=4/7

2/7x=4/7-3/8

2/7x=11/56

x=(11/56)/(2/7)

x=11/16

Column equations solve the problem.

1.Solution: This jujube tree was high when it was bought.

cm) This jujube tree is now tall.

65 cm).

2.Solution: If there are x table tennis tables for singles, then there are (12-x) for doubles, and 2x+4(12-x)=40 is obtained

The solution is x=4, so the doubles have 12-x=12-4=8 (zhang).

A: 4 table tennis tables for singles and 8 for doubles.

3.Solution: Set the basket to weigh x kilograms, get, solve x =

A: The basket weighs kilograms.

Add 5 kg of salt to () kg of water to get 20% brine selection a, 20 kg.

Work something out. A car drove from City A to City B, and the whole journey was 2 5, which was exactly 60 kilometers. How far is this car from City B now?

Solution: There are 60 (2 5)=150 (km) from city A to city B, and this car is now 150-60=90 (km) from city B. Answer: This car is now 90 kilometers away from city B.

Complete.. o(∩_o。

18，20/21

Get x = 1235 19

I'll do it tomorrow after work.

Students: If these questions are homework, it should be faster to do them yourself than to wait for the answers here.

These questions really don't have the value to ask.

Weigh 6 bags first, three on the left, three on the right if balanced, the seventh bag is light, if the left is a little lighter, remove the right one, move the left bag to the right, and put the other bag down. Below, you know, smart.

Set Zhang Ying is x years old and her father is (x + 24) years old.

x+x+24=38

x = 7 Zhang Ying is 7 years old and her father is 31 years old.

Up to 4 times, minimum 1 time.

Please adopt, thank you (talent XJH anti-counterfeiting mark).

1. Put 3 bags on each side of the scale. If both sides are equally heavy, the other 1 bag is slightly lighter; If the two sides are not the same weight, the lighter one bag is among the three bags on the high side of the scale. Take out 2 of the 3 confirmed bags and place 1 bag on each side of the scale.

If it is not the same weight, the 1 bag with the high balance is slightly lighter; If it is the same weight, the other 1 bag is slightly lighter.

2. Zhang Ying is 7 years old and her father is 31 years old.

5 years later, my father is 24 years older than Zhang Ying, so this year's father is also 24 years older than Zhang Ying. For example, Xiao Ming and Xiao Fang are the same age, so no matter how many years pass, they are both the same age.

Zhang Ying's age: (38 24) 2 7 (years).

Dad's age: 38 7 31 (years).

3. Put 4 on each side, weigh it up to 3 times to find it out at least 2 times, you can find it out.

There are 7 bags of laundry detergent and one bag is slightly lighter, can you find it out with a balance?

That's fine.

First, place 2 bags of laundry detergent at each end of the scale.

1) If the balance is balanced, then there are defective products in the remaining 3 bags, only take two of the bags and put them at both ends of the balance, if the balance is balanced, then obviously the remaining bag is defective, if the balance is unbalanced, then the remaining bag is **, then replace this bag of ** on the balance of any bag of laundry detergent, if the balance is balanced, then the bag of laundry detergent that is replaced is defective, if the balance is unbalanced, then the other end of the balance is defective, just replaced is **;

2) If the balance is unbalanced, it means that the defective products are mixed in the 4 bags of laundry detergent on the balance, and the remaining 3 bags are **. Then, take 1 bag on each side of the scale.

a) If the balance is not balanced, then the two bags taken away are also **, the defective product is still on the balance, you can replace a bag of laundry detergent on the balance with a bag of laundry detergent in the **, if the balance is balanced, then the bag of laundry detergent that is replaced is a defective product, if the balance is unbalanced, then the other end of the balance is a defective product, and it was replaced just now by **.

b) If the balance is balanced, then one of the two bags of laundry detergent taken away is defective, just take one of the bags and put it at one end of the scale, the other end is of course put a known bag **, if the balance is balanced, then the bag that is not placed on the balance is defective, if the balance is not balanced, then the bag placed on the balance is defective.

Comprehensive, it is necessary to find out the defective laundry detergent up to three times.

2.Zhang Ying and his father are 38 years old this year, and 5 years later, their father is 24 years older than Zhang Ying. How old are Zhang Ying and her dad this year?

Solution, assuming that this year's father's age is x years old, then Zhang Ying's age is 38-x years old, and he has to:

x+5)-(38-x+5)==24

x+5-38+x-5==24

2x==62

x==31 So this year's dad is 31 years old, and Zhang Ying is 7 years old this year.

3.There are 9 pearls with the same appearance, but one of them is slightly heavier, and you want to find 8 pearls of the exact same quality. If you put 4 on each side of the scale, how many times can you find it out at most? How many times can you find it out?

Solution: There are 9 pearls of the same shape, one of which is slightly heavier. She wanted to find 8 pearls of the exact same quality.

1.Without weights, can you find it out with a balance? How many times have you weighed it?

2 times is fine, 3 on the left and right.

2.If you put 4 pearls on each side of the scale, how many times can you find it? How many times can you find it out?

Weigh it up to 3 times to find it.

At least 1 time to find it.

For the first time, put three generations on each side, and if it is balanced, the bag that is not put is slightly lighter. If it is not balanced, then the slightly lighter bag is on the lighter side, and then follow the above practice to find this bag.

Time is fair to everyone, Zhang Ying and Dad are the same age, 38-24 = 14 14 2 = 7 Zhang Ying is 7 years old this year, and Dad is 31 years old this year.

Maximum 3 times, minimum 1 time.

1 can 2 Zhang Ying 7 Dad 31

3 For the first time, take 6 pieces at random and place them on both sides of the scale, 3 on each side. If the weight is the same, among the 3 that were not taken, 6 of them were excluded; If it is not equal, you can exclude the light side and the 3 that you did not take.

The second time, take 2 of the remaining 3 and place them on both sides of the scale, 1 on each side. If the weight is the same, it is the one that is not held, and if it is not equal, it is the one on the heavier side.