![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
1+2-3+4+5-6+7+8-9.97+98-99.
1+2-3=0 4+5-6=3 7+8-9=6······97+98-99=96
0+3+6+······+96=?
3+96=99 6+93=99 9+90=99·····
96/3=32 32/2=16
99*16=1584
The sum of the first three numbers is 0, 3, 6, 9, 12
There are 99 △ 3 = 33 groups
Then the sum of the last group is: (33-1) × 3 = 96
Then the above formula is transformed into: 0 + 3 + 6 + 9 + +96
（0+96）×33÷2=1089
Is it something from primary school
Original formula = 1-1 + 4-1 + 7-1 + ······ + 97-1
=（1+4+7+10+·····+97）-（1+1+······+1）
=（98+98+98+··+49）-33
=(98 times 16 + 49) - 33
=(100-2) times 16 + 16
=(100-1) times 16
=1600-16
=1584
=-100
It's 1584
The following sequence starts from the third number. Each number is the sum of the first two numbers. It is known that the third number is 4.2 and the sixth number is 18.4. How much is the first number
（X）、（）、4.2、（）、（）、18.4、…… (solved by equation)
x,4.2-x,4.2,8.4-x,12.6-x,21-2x
21-2x=18.4 2x=2.6 x=1.3
Let the fourth number be x, then 18.4 = x + X + 4.2, then x = 7.1, and then push forward
How many cars and bicycles are there in the parking lot?
4x+(35-x)x2=108
4x+70-2x=108
4x-2x+70=108
2x+70=108
2x=38
x=38/2
x=16
is it?
Sorry, I already know the answer, please!
The previous process is all right, the last x = 38 / 2, the result x = 19
Compare the following two formulas and work out the difference between them +97+99 b：2+4+6…… +98+100
_______ Than_______ Large ()
B is bigger than a
Because each addend of B is 1 larger than the corresponding addend of a, B is 50 larger than a
b，a
They have a difference of 1 to 50, so the difference is 50
B is larger than a (50)
B is 5050
A
The number of a column is determined according to the following conditions: the first is 3, the second is 6, and the third is 18. After that, each number is twice the sum of all the previous numbers, from the third to the third______ Starting from the number, each is greater than 3565
The analysis shows that each number is three times larger than the previous one, that is, the first number is 3, the second number is 6, the third number is 18, the fourth number is 18 × 3 = 54, the fifth number is 54 × 3 = 162, the sixth number is 162 × 3 = 486, the seventh number is 486 × 3 = 1458, the eighth number is 1458 × 3 = 43744374 > 3565
In a parking lot, there are 32 cars and motorcycles with 108 wheels in total. How many cars and motorcycles are there respectively? (formula)
(108-2 × 32) / (4-2) = 22 cars 32-22 = 10 motorcycles
8,6,7,5,( ) ( )
7,8,6,7,5,( 6 ) ( 4 )
Odd items 7,6,5,4
Even items 8,7,6,5
3 and 1
64
The rule is + 1-2
"7“+1="8"-2="6"+1="7"-2="5"+1="6"-2="4"
So it should be followed by 6 4
7,8,6,7,5,(6),(4)
Because 7 + 8 = 15
8+6=14
6+7=13
7+5=12
So 5 + the next number = 11 gets this number = 6
6 + next number = 10 gets 4
So the answer is 6, 4
64
7,8,6,7,5,( 6) (4 )
The difference is 1
6 4
The first one is one less than the last one, and the third one is two less than the second one
Add one and then subtract two
So it's 7 8 6 7 5 6 4
7,8,6,7,5（6）（4）
Two times of a number is 6 more than 18. What is the number? Use the equation to calculate
2x=18+6
X = 24 divided by 2
x=12
There are 7 tricycles and cars in the parking lot, with a total of 25 wheels. There are () tricycles and () cars
A tricycle x a car y
Then x + y = 7
3x+4y=25
The solution is x = 3, y = 4
There are three tricycles and two cars.
3 * 7 = 21
25-21 = 4
4 / (4-3) = 4 vehicles
7-4 = 3
Three tricycles and four cars
Three tricycles and four cars.
3×7＝21
4-3＝1
Car: 4 △ 1 = 4
Bicycle: 7-4 = 3
That's what the teacher taught.
3.5.8.13 what should be
21 34 55
Starting from the third number, it is each of the first two numbers. 5 = 3 + 28 = 5 + 3
The answer is over. I wish you a happy day and thank you on your knees!
The third number is equal to the sum of the first two numbers
What should be the rule of online solution of primary school mathematics problem 2.3.5.8.13
Answer: 2.3.5.8.13 [21] [34] [55]
The rule is that the first number + the second number = the third number, and the second number + the third number = the fourth number.
21 34 55
Starting from the third number, it is each of the first two numbers. 5=3+2 8=5+3 13=8+5 【21】=13+8 【34】=21+13 【55】=34+21
2.3.5.8.13【21】 【34】 【55】
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