Observation formula: 1 + 3 = (1 + 3) × 22, 1 + 3 + 5 = (1 + 5) × 32, 1 + 3 + 5 + 7 = (1 + 7) × 42 Fill in the blanks according to the rule: 1 + 3 + 5 + 7 + +99=______ ．

Observation formula: 1 + 3 = (1 + 3) × 22, 1 + 3 + 5 = (1 + 5) × 32, 1 + 3 + 5 + 7 = (1 + 7) × 42 Fill in the blanks according to the rule: 1 + 3 + 5 + 7 + +99=______ ．

1+3+5+7+… +99=(1+99)×502=2500．

1-3 + 5-7 + 9-11 +... + 97-99 simple algorithm steps!

1-3+5-7+9-11+...+97-99
Group two numbers
1-3=-2
5-7=-2
9-11=-2
.
97-99=-2
Total (99 + 1) / 4 = 25 groups
1-3+5-7+9-11+...+97-99
=-2*25=-50

3 / 4 × 96 + 3 / 4 + 0.75 is simple

Original form
=3/4x96+3/4x3+3/4x1
=3/4x(96+3+1)
=3/4x100
=75

3.6 × 0.75 + 3.6 △ 4 (simple calculation)

3.6×0.75+3.6÷4
= 3.6×0.75+3.6x0.25
=3.6x(0.75+0.25)
=3.6x1
=3.6

An applied problem of mathematical inequality in junior middle school
A certain education administrative department of our state plans to organize some teachers to study in other places this summer vacation. When booking hotel accommodation, there are two Hotels with the same accommodation conditions, one is a hotel and the other is B hotel. The charging standard is 120 yuan per person per day, and each offers different preferential schemes, If you are in charge of this department, which hotel should you choose is more affordable?
Claw machine, small picture can't see clearly!

Suppose the total number of people is x, when x ≤ 35, it is the same to choose two hotels; when 35 < x ≤ 45, it is cheaper to choose hotel a; when x > 45, the charge of hotel a is y a = 35 × 120 + 0.9 × 120 × (x-35), that is y a = 108x + 420; y B = 45 × 120 + 0.8 × 120 (x-45) = 96x + 1080, when y a = y B

In the maintenance process of a bridge, team a and team B plan to complete a project together. It is known that team a needs 40 days to complete the project alone, with a daily construction cost of 6000, while team B needs 60 days to complete the project alone, with a daily construction cost of 35000. To make the total construction cost not more than 220000, how many days should team B construct at least?
What the teacher asked for is a solution of inequality

Let team B construct for X days, and team a construct for y days from 1 / 40y + 1 / 60x = 1 to get y = (120-2x) / 3 to 0.6y + 0.35x ≤ 22 to get 24-0.4x + 0.35x ≤ 22  x ≥ 40. Answer: Team B must construct for at least 40 days ↖ (^ω^) ↗ Remember: mathematics will be more and more difficult, but as long as you always keep a sincere enthusiasm, you will play

There are 98 pages in an English book. Zhang Li hasn't finished reading it in a week (7 days), but Li never finished it in a week. Li Yongping reads 3 more pages than Zhang Li every day. How many pages does Zhang Li read every day? (the answer is rounded)

Let tension read x pages every day on average, then Li Yongping reads (x + 3) pages every day. According to the title meaning 7x < 987 (x + 3) > 98, (5 points), 11 < x < 14. (8 points) because x is an integer, x = 12 or 13. Answer: Tension reads 12 or 13 pages every day on average

Junior high school mathematics inequality application questions and answer set

What do you want? Please make it clear

On the junior high school mathematics inequality application problem
This year's drought in Guizhou Province, the Provincial Youth League Committee organized some middle school league members to send water to Erlong village. A school Youth League branch received a truck of mineral water. If each person sent 4 boxes, there were 37 boxes left. If each person sent 6 boxes, the last person had water, but less than 3 boxes. How many boxes are there in this truck?

There are x persons in total
6X-3＜4X+37①
4X+37＜6X②
The solution of inequality (1) is: x < 20
The solution of inequality 2 is: x > 37 / 2
The solution set of this inequality system is 37 / 2 ＜ x ＜ 20
∵ x can only take integers
∴X=18,19
When there are 18 people: 4 × 18 + 37 = 109 (boxes)
When there are 19 people: 4 × 19 + 37 = 113 (boxes)
A: there are 109 or 113 cases of water in this truck
or
0

2010-11-19 simple: (9 and 2 / 3) square minus (1000 and 1 / 3) square

This problem uses the square difference formula
The original formula = (9 + 2 / 3) & # 178; - (1000 + 1 / 3) & # 178;
=(9+2/3+1000+1/3)(9+2/3-1000-1/3)
=1010 × (- 990 and 2 / 3)
=- (1000573 and 1 / 3)
I hope it will help you