Baidu asked Xiaoming to do math problems, each right one plus 10 points, do a wrong deduction of 5 points, a total of 10 questions, the final 55 points ask right and wrong each several questions extra urgent

Baidu asked Xiaoming to do math problems, each right one plus 10 points, do a wrong deduction of 5 points, a total of 10 questions, the final 55 points ask right and wrong each several questions extra urgent

Suppose Xiao Ming does everything right, he should get 10 * 10 = 100,
Compared with the actual score of 55, it is less: 100-55 = 45,
If you do a wrong question, you will not only get no score, but also get 5 points. Therefore, if you do a wrong question, you will get 10 + 5 = 15 points less than if you do a right one,
Wrong questions: 45 / 15 = 3
Correct question: 10-3 = 7

A very, very simple math problem. One minute,
The following table shows the percentage of plain, water area, mountainous area and hilly area in Anhui Province
Plain water, mountain and hill
Accounting for 31.3% 8.0% 31.2% 29.5% of the total area of the whole province
1. The ratio of the area of plain in Anhui Province to that of the whole province is ()
2. The ratio of water area in Anhui Province to that of the whole province is ()
3. The ratio of the total area of mountains and hills in Anhui Province to that of the whole province is ()
4. What is the main terrain in Anhui Province?

The following table shows the percentage of plain, water area, mountainous area and hilly area in Anhui Province
Plain water, mountain and hill
Accounting for 31.3% 8.0% 31.2% 29.5% of the total area of the whole province
1. The ratio of plain area in Anhui Province to the whole province is (31.3%)
2. The ratio of water area in Anhui Province to that of the whole province is (8.0%)
3. The ratio of the total area of mountains and hills in Anhui Province to that of the whole province is (60.7%)
4. What is the main terrain in Anhui Province?
plain

Xiaoming's mother took out Xiaoming's clothes and said, "two days ago, there was a discount in the store. Today, on the basis of a 20% discount, the price was reduced by 10%. As a result, it cost 144 yuan to buy it. Do you know the original price of the clothes?" the price is 144. At this time, the profit margin of the clothes is 20%. Can you work out the purchase price?

[144 / (1-10%)] / 0.8 = 200
144 / (1 + 20%) = 120 purchase price 120

It is known that in the rectangular coordinate plane, point a (- 3,4) is on the terminal edge of angle α, vector OA rotates π / 3 anticlockwise around the origin o to ob, and point B falls on the terminal edge of angle β. The values of sin2 α and cos β are calculated

Because point a (- 3,4) is on the terminal edge of angle α, OA = r = 5. From the definition of sine and cosine, sin α = 4 / 5; Cos α = - 3 / 5. Sin (2 α) = 2Sin (α) cos (α) = 24 / 25. And β = α + π / 3. Cos β = cos (α + π / 3) = cos α cos (π / 3) - sin α sin π / 3 = - (3 + 4 square root 3) / 10

The school rents several large trucks for the students participating in the summer camp. If each car takes 28 people, 14 students can't get on the car. If each car takes 35 people, one less car can be rented. How many students are there?

Hello
Set X cars
28x+14=35(x-1)
28x+14=35x-35
35x-28x=14+35
7x=49
x=7
A total of 28x7 + 14 = 196 + 14 = 210 people
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The sum of two continuous natural numbers is 191. What are the two natural numbers
Lie equation

Let the decimal be X
X+X+1=191
2X=190
X=95
The two numbers are 95 and 96

Let m and n be real numbers. If the operation symbol "*" is defined as m * n = m ^ 2-N ^ 2 + 2m + 3N, and what is the value of X, the value of formula x * x-3 is 17

x*x-3=17
x^2-x^2+2x+3x-3=17
5x=20
x=4
When x = 4, the value of X * x-3 is 17

During the National Day holiday, several students rent a van to travel to a certain place. The rent of the van is 120 yuan. Two more students joined in when they set out. As a result, each student shared 3 yuan less, so the number of students who used to travel was 120 yuan

Starting number: X, per capita y yuan
XY=120
(X+2)(Y-3)=120
We get x = 8, y = 15

Limit: LIM (1 + 1 / x) (2-1 / X & # 178;)

LIM (1 + 1 / x) (2-1 / X & # 178;) = LIM (x + 1) / X · (2x & # 178; - 1) / X & # 178; = LIM (x + 1) (2x & # 178; - 1) / x ^ 3 = Lim (2x ^ 3 + 2x ^ 2-x-1) / x ^ 3 if x tends to infinity, then LIM (1 + 1 / x) (2-1 / X & # 178;) = 2 has the same power of the highest power, and the limit is the highest power

Find: LG (x times + 2 of 4) = x times + Lg3 of LG2

LG (x times of 4 + 2) = x times of LG2 + Lg3
lg(4^x+2)=lg(2^x*3)
So, 4 ^ x + 2 = 3 * 2 ^ X
(2^x)^2-3*2^x+2=0
(2^x-1)(2^x-2)=0
2^x-1=0
x=0
2^x-2=0
x=1