The solution of the equation of one variable and one degree (2) Ningbo's

The solution of the equation of one variable and one degree (2) Ningbo's

1. D 2. B 3. D 4. The equation can't be worked out, only can tell you the answer: x = - (6 + √ 2) / 4 5. Same as above. X = - (22 / 19) 6. B 7. (x-k) / 4 = K + (x / 6) x = 15K K K (2 + x) = (K + 2) x x x x = K

Ask a few practical problems of linear equation of one variable, including solution, steps and answers,
1. In the entrance experience of a class in senior one, the average weight of the whole class is 48 kg. The average weight of male students is 20% heavier than that of female students, and the number of female students is 20% more than that of male students
2. Assign a batch of 490 tons of cargo to ship a and ship B for transportation. Now ship a and ship B have transported 5 / 7 and 3 / 7 of the number of tasks respectively. Among the cargo already transported, ship a carries 30 tons more than ship B. how many tons of tasks are assigned to ship a and ship B?
3. Car a and car B go from city a to city B at the same time. Car a travels 35 kilometers per hour and car B 40 kilometers per hour. As a result, car B arrives at city B half an hour earlier than car A. how many kilometers is the distance between city a and city B?

There are three consecutive integers. Given that the sum of the smallest number plus two times of the middle number plus three times of the largest number is 68, find these three consecutive integers
Let the value of the smallest number be X
x+2（x+1）+3（x+2）=68
6x=60,
X = 10. So the three consecutive integers are 10, 11 and 12 in turn
A strange plant has been cultivated in the laboratory. It grows very fast. Every day, it grows to 3 kg more than twice the weight of yesterday. After 3 days of cultivation, the weight of the plant reaches 45 kg. How many kg does this plant have?
Let's suppose that this plant has a weight of x kg
2×（2×（2×x+3）+3）+3=45
x=3
So this plant used to weigh three kilograms
At the beginning of the new semester, there are a number of new textbooks to be distributed to all students. These textbooks must be moved by a group of students. If the boys in the group move 25 textbooks each, there are still 15 textbooks that have not been moved. If the girls in the group move 20 textbooks each, So the last girl only needs to move 10 books. There are 8 students in this group. How many boys and girls are there?
Suppose the number of boys in this group is x, then the number of girls is 8-x
25x+15=20（8-x）-10
25x=160-20x-25
45x=135
x=3
So there are 3 boys and 5 girls in this group
Ding Ding and Lingling picked apples. Ding Ding said, "give Lingling seven apples I picked, and the number of apples Lingling picked is twice as many as mine." Lingling said, "give Ding seven apples I picked, and the number of apples he picked is as many as mine." how many apples did Ding Ding and Lingling pick?
Shedding picked x apples,
x+7=2（x-7）-7-7,
x +7=2x-14-7-7,
7+14+7+7=2x-x,
x=35.
Lingling's number of apples is 2 (X-7) - 7 = 49

Set up equations to solve practical problems,
If you order a periodical less than 100 copies by mail, you need to add 10% of the book price for postage. If you order more than 100 copies by mail, you will be free of postage. It is known that the price of this periodical is 5 yuan per copy. The total cost of a person's two mail orders is 152 copies (the second one is more than 100 copies). The total cost is 776 yuan?

Let the second time be X
5x+(152-x)*5*(1+10%)=776
5x+152*5.5-5.5x=776
0.5x=152*5.5-776
x=120
152-120=32
32 for the first time
120 copies for the second time

Chase and meet the solution of one variable linear equation (please specify) thank you!
For the encounter in pursuit of the problem, set the X will not ask, what method does the master have?
Meeting examples
(1) Ships a and B sail between a and B at a speed of 35km per hour from a to B and 25km per hour from B to A. ship a sails from a to B, and ship B sails from B to A. ship a goes ahead for 2 hours, and the two ships meet at 120km from B. find the distance between the two places and the sailing time of ship a when they meet
A starts from a at 6 a.m. and arrives at B at 5 p.m. on foot. B starts from a at 10 a.m. and arrives at B at 3 p.m. on bicycle
(2) A starts from place a by bicycle and drives to place B at the speed of 12km / h. After 15min, B starts from place B by bicycle and drives to place a at the speed of 14km / h. When two people meet, B exceeds the midpoint by 1.5km and calculates the distance between two places
This is my weakness. I want to make it up
How about the equations? Is there any formula

The distance problem, on the three basic elements, distance = speed × time, others are based on this change. Pursuit problem pursuit distance = speed difference × pursuit time encounter problem encounter distance = speed and × encounter time, use the equation to solve the application problem, to find a good equivalent relationship. 1