If the values of 5x-8 and 3x are opposite to each other, then X=

5X-8= -3X
X=1

1. If 3x-2 and 4-5x are opposite to each other, find the value of X
thank you

3x-2=5x-4 ,x=1

General term formula of mathematics compulsory 5 3 8 13 18

Add 5 at a time
So an = - 2 + 5N

It is known that the radius of the sun is 7 × 10 to the eighth power meter, and the radius of the earth is 6.4 × 10 to the sixth power?
Don't copy! Be specific and score high
I just can't understand the process!
PS, (keep two significant numbers. Take 3.14 for π)

Multiple = (7 × 10 ^ 8) ^ 3 ÷ (6.4 × 10 ^ 6) ^ 3
=(343×10^24)÷(262.44×10^18)
≈1.3×10^6

1. A store bought two pieces of clothing A and B for 600 yuan. In order to make a bigger profit, the store owner decided to price the clothing a at 50% of the profit and the clothing B at 40% of the profit. In actual sales, the two pieces were sold at a 10% discount, and the profit was 174 yuan. How much was the purchase price of the two pieces of clothing?
2. There are 50 students in class 2 of Grade 7 in a school. According to statistics, the annual expenditure of drinking water for each student is a yuan. It is predicted that if the class drinks bottled purified water instead, the annual total cost consists of two parts, one is the cost of purchasing purified water, and the other is the other 780 yuan. If the selling price is 40 yuan per barrel, 400 barrels will be needed every year. If the price increases by 1 yuan, 80 barrels will be used less
(1) Suppose that bottled water is sold in Y barrels, the selling price is x yuan per barrel, and the algebraic expression of X is used to express y;
(2) If the class needs 380 barrels of purified water every year, a = 120, which one costs less, drink or purified water?
3. Some of the same rooms need painting. If three first-class technicians go to paint four rooms, the result is that 44 square meters of walls have not been painted; in the same time, seven second-class technicians paint six rooms, but also paint another 14 square meters of walls. Each first-class technician paints 10 square meters more in one day than the second-class technician
(1) For each room painting area;
(2) If 20 people from two kinds of craftsmen are used to paint 20 rooms at the same time, how to arrange the construction?
4. Liji town of Huangpi District organized 20 vehicles to load 100 tons of oranges a, B and C to Wuhan for sale. According to the plan, 20 vehicles can only load the same kind of oranges and must be filled up. The information is as follows:
Variety a B C
Profit per ton / 100 yuan
(1) Let X be the number of type a vehicles and y be the number of type B vehicles;
(2) If the total profit is 140800 yuan, how to arrange the transportation?

1. Let a's purchase price be x yuan, then B's purchase price be (600-x) yuan. From the problem, we can get the equation [x (1 + 50%) + (600-x) (1 + 40%)] × 90% - 600 = 174. From the solution, we can get: x = 200600-x = 4002. (1) from the problem, we can get: y = 400 - (x-40) × 80y = 400-80x + 3200y = - 80x + 3600

After the natural numbers are arranged according to the following table, they can be divided into five columns: one, two, three, four and five. For example, 12 is in the third row of the fourth column and 16 is in the fourth row of the second column
So, what column and row is 2000 in?
One two three four five
1 2 3 4 5
9 8 7 6
10 11 12 13
17 16 15 14
.

Column four, line 500
According to the sum of continuous numbers (2000-5) △ 4 = 498 three
Because the first line is omitted and the line of 2000 is not full,
(so) 498 + 1 + 1 = 500 to get the line
The key is to find the third column, but it's very tangled. Since it's the third column, it's either in the third or the fourth column
There are two ways:
① If we don't look at the first line, 2000 will be in line 499, and if there is no space before the odd line, it will be the third column;
② But we can find that the number of the third column is odd, the fourth column is even, 2000 is even, then it is the fourth column
Finally, although there are two kinds of conclusions, we have to take the following: column 4, line 500

All negative integers with absolute values greater than 2.5 and less than 7.2 are______ ．

∵ if the absolute value is greater than 2.5 and less than 7.2, it can be set as X, ∵ if there are 2.5 ＜| x | 7.2, ∵ x | = 3, 4, 5, 6, 7, ∵ if the absolute value is greater than 2.5 and less than 7.2, all negative integers are: - 3, - 4, - 5, - 6, - 7; so the answer is: - 3, - 4, - 5, - 6, - 7;

As shown in the figure, the two diagonal lines AC and BD of quadrilateral ABCD are perpendicular to each other. A1, B1, C1 and D1 are the midpoint quadrilateral of quadrilateral ABCD. If AC = 8 and BD = 10, the area of quadrilateral a1b1c1d1 is___ ．

∵ A1, B1, C1, D1 are the midpoint quadrilateral of the quadrilateral ABCD, and AC = 8, BD = 10 ∵ a1d1 is the median line of △ abd ∵ a1d1 = 12bd = 12 × 10 = 5. Similarly, A1B1 = 12ac = 4 can be obtained. According to the median line theorem of triangle, it can be proved that the quadrilateral a1b1c1d1 is a rectangle, so the area of the quadrilateral a1b1c1d1 is a1d1 × A1B1 = 5 × 4 = 20

There are 350 balls of three colors in the box. The ratio of yellow ball to red ball is 2:3, and the ratio of red ball to white ball is 4:5. How many balls are there in each of the three colors?

The ratio of yellow to red is 2:3 = 8:12, and the ratio of red to white is 4:5 = 12:15
Then, the ratio of yellow ball, red ball and white ball is 8:12:15
8+12+15=35
Therefore, there are: 350 × 8 / 35 = 80 yellow balls
Red ball: 350 × 12 / 35 = 120
White ball: 350 × 15 / 35 = 150

How many centimeters is eight inches

2.54cm * 8

If the values of 5x-8 and 3x are opposite to each other, then X=