How to write these two questions, it is best to have an explanation. Be explained. Mathematics in th

The angle b is equal to the angle c, and the 5x angle c is equal to 180 degrees'Angle B is equal to angle C is equal to 36 degrees, and angle DAC is equal to 36 degrees. The outer angles of the bad72 degree triangle are equal to 3 inner angles that are not adjacent to it and adb72 degrees ,,,.

1 In the case of no adjustments.

Car rental cost: 8*12*10,000.

The cost of buying a car: 12 + 8 * million yuan.

It is advantageous to buy a car. 2 In case of adjustment.

Car rental cost: 3*12*10,000. Cost of buying a car:

10,000 yuan is still cost-effective to buy a car.

Car rental: (1) 10,000 yuan for the first 3 years).

2) After 5 years: 10,000 yuan).

Total 10,000 yuan. Buying a car: (1) Buying a car: 120,000 yuan.

2) Insurance premium: 10,000 yuan).

3) Maintenance fee: the first 3 years: 10,000 yuan (free maintenance in the first year) after 5 years: 10,000 yuan).

A total of 12+ million yuan).

Obviously, buying a car is a good deal.

8-year rental cost: (1) the first 3 years: 10,000 yuan) (2) the next 5 years: 10,000 yuan) total 10,000 yuan.

Cost of buying a car in 8 years:

1) Fare: 120,000 yuan.

2) Insurance premium: 10,000 yuan).

3) Maintenance fee: the first 3 years: 10,000 yuan.

After 5 years: (10,000 yuan).

A total of 12+ million yuan).

First of all, if you don't play these two places, you can board the plane directly, and it will take 70 50 = Then, if you go to 2 places, one will take 2 hours more, and the other will use 1 hour more, which is a total of 3 hours more than the original

Therefore, if you go to these two attractions again, it is public.

It is less than 5 hours, so it will not affect boarding.

No: It is known from the title: the city construction committee that completed the trip 70 50 = so the total remaining time is hours.

It takes 3 hours to visit both places, so there are still hours left, so there is no delay in waiting for the plane.

It won't be 5-(2+1)=2 hours 70 50=hours 2 is greater than So it won't affect the rush to the Three Gorges Airport to board the plane.

1. From the original question, 3y-1=-(1-2x)=2x-1, so y=2x 3, can only get the relationship between x and y, but not the specific value.

The square root of , and the cubic root of 7, are not rational numbers, so they must be converted to rational numbers. The method is to the power of three numbers at the same time to the 6th power, and get , because 125>49>8, the square root of 5 >> the square root of 7 >> 2. The number with the root number is so compared.

3. Knowing v=, find s=6a 2, so, s square meters.

4. If the width is a meter, the length is 3a meter, and the length is 3a meter, s=3axa=3a 2=1200000000, so, a 2=40000000, a = 2000 root number 10, and because the root number is 10<5, so 2000 root number 10<10000. < 10 < can be taken as an approximation of the root number 10, so the width a = 6300 meters.

1. From the meaning of the title, it can be seen that 3y-1 and 1-2x are opposite numbers to each other, that is, 3y-1=-(1-2x).

If there are no special conditions.

There are countless solutions to this problem.

2. You don't need to count the cube root of 7.

The square root of 5 is, and the cube of the square root of 5 is.

The cube of the cube root of 7 is 7, and it is clear that 7 is less than.

Then the cube root of 7 is less than the cube root.

That is, the cubic root of 7 is less than the square root of 5.

3. The cube root of the edge length of the cube tank is meters.

Its surface area is: square meters.

4. Let its width be x, then its length is 3x

x×3×=120000000

3x squared = 120000000

x squared = 40000000

x=square root, I'll calculate, but it's not easy to say, just see if you can understand 1With the decimal point as the center, each two digits are divided into a section of 2Take the first section opening as an under-approximation, which is the first digit of the root.

3.Subtract the square of the first digit from the first stanza to get the difference and the second stanza to form the first remainder.

4.Multiply 20 by the first digit to try to divide the first remainder, and the test divisor is the second digit of the root.

5.Subtract the product of the second digit and the divisor from the first remainder, and the resulting difference and the next section spell out the second remainder.

6.Multiply 20 by the first two digits of the root, and try to divide the second remainder by the third digit of the root.

7.In this way, you can find the required number of digits.

Note: If the divisor is greater than or equal to 10 in the operation, 9 is taken

The cube root of 1:3y 1 and the cube root of 1 2x are opposite to each other, find x=? y=?

Answer: According to the question, 3y 1 (1 2x) 2x 1 can get the relationship between x and y, so x 3 2y, y 2 3 x.

2: 2, square root of 5, square root of 7, compare size. How do you calculate the cube root of 7?

Answer: There is no need to calculate the cube root of 7, just the power of the three numbers at the same time (the least common multiple of the three numbers open root exponents), this title is three numbers at the same time to the 6th power, and we get , because 125 49 8, so the square root of 5 The square root of 7 and the square root of 2.

3: A factory wants to weld a closed square water tank with a sheet of iron, his volume is cubic meters, and asks how much area of iron sheet is needed?

Answer: Let the side length of the cube be a, then the cubic meter of a is calculated as a meter; The side length of the iron sheet is 3a when the square water tank is closed, so the area of the iron sheet required is 3a 3a 9a a 9 square meters.

4: A development zone is a rectangle three times as long as it is wide, and its area is 120,000,000 square meters. Is there 10000 meters? If the required error is less than 100 meters, what is his width?

Answer: According to the topic, the width is set to a meter, then the length is 3a meters, and the area is 3a a 120000000, so a a 40000000, a 2000 root number 10, because the root number is 10 4, so the 2000 root number is 10 2000 4 8000, so the width is not 10000 meters. Whereas, it is desirable to take the average value with the root number 10 as an approximation, so that his width a 2000 m.

Another problem is that there is no way to get the exact cube root or square root of the number that cannot be divided like 2 and 7, but some such as the second question, what should I do if I need to compare the size? Note: Do not count as a cyclic decimal.

Answer: Like I answered the second question earlier, if you want to compare the size of several undivided numbers, you only need to count several numbers at the same time (the least common multiple of the opening exponent of several numbers) to the power, and it is easy to compare the size by unifying them into integers, and you don't need to count them as cyclic decimals.

The unit price after mixing is x yuan, and the original unit price of material A is x+3 yuan.

The original unit price of material B was x-1 yuan.

Therefore: [(2000+4800) x] = (2000 x+3) + (4800 x-1).

6800/x=（2000/x+3）+(4800/x-1)

6800*(x+3)*(x-1)=2000*(x-1)*x+4800*(x+3)*x

6800x2+13600x-20400=2000x2-2000x+4800x2+14400x 1200x=20400

The unit price after x=17 is 17 yuan.

Solution: Let the first raw material be x yuan per kilogram, and the second raw material should be y yuan per kilogram x-3=y+1

2000 x+4800 y)x(x-3)=2000+4800 is substituted by x-y=4 to the minimum, and x=20 y=16

20-3=17 (yuan).

17 yuan per kilogram after mixing.

1.Let it be: 3y-1=1-2x

So: 2x+3y-2=0

2.Multiply the root number 5 by the root number 3 7 by the 6th power at the same time, respectively, 125 and 49, so the former is 3Because its volume is cubic meters, its side length is meters. Therefore, its surface area is: 6* square meters) so the area of iron sheet is square meters.

4.Let the width be a, then there is: 3a 2 = 120000000, so a = 2000 meters ......

The cube root gives the side length of its square, and multiplies the square by 6 to get the square meter, so the area is square meters.