Desperate for 7th grade univariate equation math answers? Hurry, hurry

Solution: There is an implicit condition to be used here, the summer vacation is generally in July and August.

If the date of Xiao Wang's first day at his uncle's house is x, then the corresponding date of seven days is.

x,x+1,x+2,……x+6

The sum is 7x+21=7(x+3).

If you went in July, then.

7(x+3)7=84,x=8

So Xiao Wang stayed at his uncle's house until 14, and he should have returned home on July 15.

If you went in August, then.

7(x+1)+8=81

X doesn't have an integer solution, so it's impossible, so Xiao Wang went on July 8 and went home on July 15.

Without considering the situation at the end of July and the beginning of August, the landlord can dispose of it by himself

According to the title, if 7 consecutive days are in the same month, then the sum of dates is a multiple of 7. 84 is a multiple of 7, so the month is also a multiple of 7, so it can only be July, so the sum of the days of the 7 days is 77, assuming that the date of the 7th day is x, the equation is.

7x-1-2-3-4-5-6=77

Get x=14

So it's July 14th.

Set the day of the month x to return home, then you can list the equation.

x+(y-6）+（y-5）+(y-4)+(y-3)+(y-2)+(y-1)+y=84

x+7y=105

Both x and y must be integers, so y is an integer only if x=7.

Therefore, x=7, y=14

Therefore, Xiao Wang went home on July 14.

Assuming that there is no change in the month, then assume that the day of residence is the number of x; then x+x+1+x+2+x+3+x+4+x+5+x+6+month=84

That is: 7x+21+month=84

7x + months = 63

Because it's summer vacation, the month is 7,8,9, and the result is an integer number, which can only be July, then x=8, then go home on July 14;

84 7 = 12, or 11 more than 7, 10 more than 14...

But only 1 December, take July.

77 7 = 11, with an average date of 11

Then it should be 8, 9, 10, 11, 12, 13, 14, July 14, and I should go home.

Last month, it could have been 29, 29, 30, 31 days.

The 7-day dates add up to a multiple of 7.

Only 7*8+28=84

So, the date of the fourth day is March 8.

He went on March 5.

January 14; February 13; March 12; April 11; May 10; June 9; July 8; August 7;

This doesn't seem to be good, but it can ...... every month from January to AugustWords of January: 8th to 14th.

February: 7th to 13th.

In March: 6th to 12th.

And so on. There is also the possibility of crossing the month, which does not take into account ......Or maybe I misunderstood.

Forgive me for not asking for an answer.

Because there is no answer to this question below.

Why: Everyone knows it.

The maximum value for a date is 31 and the maximum value for a month is 12

12 + 31 + 12 + 31 = 86 is 2 larger than 84, and this calculation seems too ideal, and December is still summer vacation can only say that he is in the southern hemisphere;

Think for yourself.

1、a=1

2, x=13, x=(b-ab) a, did you make a mistake in the question, 4, m=-2, this is also wrong.

5. x has an infinite number of x<=3

The year is (11 10) (11 10) (9 10) (9 10) (9 10) in 02

7、（v-v0）/a。。。Third.

Ton... $14.

x-kx=17

x（9-k）=17

x=17/（9-k）

To have an integer solution, 9-k must be equal to plus or minus 1, plus or minus 17

Find k separately

11, m+2=2 and one-half... Two-seventh.

3. Is the title wrong?

4. It seems to be written incorrectly, you read it again.

5. Countless ones.

The annual turnover is 02 years.

7、t=v-v0/a，1/38、x=7/9，14

Simple: (1)1-2(4+x)=3 x=-52) 3(x-2)+1=5 x=10 resistant 33) 10x+3=3(2x+1)-(3-x) x=-14) 3(2x-3)-2(x+4)=4(3-x)+3 x=4 and Lu: 3(x+5)+5 [(x+5)-1]=7(x+5)-1 x=-1

Example 1: 3 times minus 2 of a certain number is equal to the sum of a certain number and 4, find a certain number Solution 1: (4+2) (3-1)=3

Answer: A certain number is 3

Solution 2: Let a certain number be x, then there is 3x-2=x+4 solution, and x=3 is obtained

Answer: A certain number is 3

Example 2: Flour stored in a flour warehouse is shipped out.

After 15, there are 42 left

500 kg, how much flour was there in this warehouse?

Teachers and students jointly analyze:

1 What are the known and unknown quantities given in this question?

2 What is the equivalence relationship between known and unknown quantities? (Original weight - shipped weight = remaining weight).

3 If there are x kilograms of flour in the original place, how many kilograms of flour can be expressed as shipped flour? Using the above equality relation, how do you lay out the equation?

The above analysis process can be listed as follows:

Solution: Suppose there were x kg of flour, then 15 x kg was shipped, and x-15 x = 42 was obtained from the title

500, so x=50

A: I see.

50,000 kg of flour

Set x people to produce bolts, 100-x people to produce nuts.

18x=27(100-x)

18x=2700-27x

45x=2700x=60

The number of workers assigned to process bolts and nuts is 60 and 40 respectively.

The essence of this question should be to test a system of binary equations. The method of setting only one unknown is feasible, but it is not very good, and it is analyzed from the level of consciousness. It can be set up for x people to produce bolts and y people to produce nuts.

18x=27y (1)x+y=100 (2)The solution is: x=60, y= 40

A: There are 60 people who process bolts and 40 people who process nuts.

Solution: If the person who processes the bolt is y, then the person who processes the nut is (100-y) person.

18y=27（100-y）

45y=2700

y=60100-60=40 people.

A: There are 60 people who process bolts and 40 people who process nuts.

Set up x bolt workers and 100-x nut workers.

18x=27（100-x）

18x=2700-27x

45x=2700x=60

So there are 60 bolt workers and 40 nut workers.

Example 1 3 times minus 2 of a certain number is equal to the sum of a certain number and 4, find a certain number Solution 1: (4+2) (3-1)=3

Answer: A certain number is 3

Solution 2: Let a certain number be x, then there is 3x-2=x+4 solution, and x=3 is obtained

Answer: A certain number is 3

Example 2 After the flour stored in a flour warehouse is shipped out of 15, there are still 42 500 kg of flour left, how much flour is there in this warehouse?

Teachers and students jointly analyze:

1 What are the known and unknown quantities given in this question?

2 What is the equivalence relationship between known and unknown quantities? (Original weight - shipped weight = remaining weight).

3 If there are x kilograms of flour in the original place, how many kilograms of flour can be expressed as shipped flour? Using the above relationship between the finches and so on, how to lay out the equation?

The above analysis process can be listed in the following tables:

Solution: Suppose there were x kg of flour, then 15 x kg was shipped, and the title was obtained.

x-15 x=42 500, so x=50 000 Answer: There were 50 000 kg of flour

Example 1 3 times of a certain number and minus 2 is equal to the sum of a certain number and 4, find a certain number Let a certain number be x, then there is 3x-2=x+4 3x=x+4+2 3x-x=6 2x=6 x=3 It is absolutely like a wise hand to take a certain number as 3

1x/30-15/60=x/2/30+x/2/604x-30=2x+x

x = 30 to the station 30 km.

2x/60+（x+15）*2/60=1

x+2x+30=60

x = 10 There are 10 people in the first part.

2 questions are available in math books.

I can't do 1 question.

It's best if you listen to the teacher.

You also need to run x kilometers.

x/50+6/60=x/40

x/50-x/40=-1/10

x/200=-1/10

x=20 needs to run 20 kilometers, which can make up for the lost time.

The **** of product A is X yuan per piece.

Then the **** of commodity B is: (2800-100x) 80 = (35-5x 4) yuan Zheng chain per piece.

So: x(1+15%) 100+(35-5x 4)(1+10%) 80=3140

115x+（2800-100x）×

115x+3080-110x=3140

5x=60x=12

The ** of product B is 35-15=20

Therefore, the ** price of a businessman shouting that the first price of Sun Pin is 12 yuan per piece.

The ** price of commodity B is 20 yuan per silver old piece.

If you don't understand, you can ask. Thank you.

Set a commodity X yuan per piece.

15%+1)x+(2800-100x)/80*(10%+1)=3140

A selling price (total square foot, first purchase price - A total number of tombs, purchase price) = B total purchase price 80 = B unit price * increase = B selling price.

A selling price + B selling price = 3140 total selling price.

The ** price of A commodities is X, because 100 A commodities and 80 B commodities cost a total of 2,800 yuan, so the ** price of B repentance is (2800-100x) 80 = 100 * (1 + 15%) x + 80 * (1 + 10%) (5 x = 60).

The ** price of A commodities is x, because 100 A commodities, 80 B commodities are hail, and a total of 2800 yuan is spent, so the ** price of B commodities is Xiang Qingfan (2800-100x) 80 = 100 * (1 + 15%) x + 80 * (1 + 10%) (5x = 60).

x=12 So the **unit price of commodity A is 12 yuan, and the unit price of commodity B is yuan.