Mathematics application problems in the second year of junior high school, urgent and urgent!!!! It

Solution: It takes x and y days for companies A and B to complete the task separately.

Then the system of equations is obtained according to the meaning of the question:

2/x＋3/y＝1/2

2/x＋（x＋1）/y＝1

x^2－9x＋8＝0

Don't remove the denominator, multiply the upper equation by x 1, multiply the lower equation by 3, and subtract it again) to get x 1 (undesirable, rounded) or x 8

Substitute to get y 12

Answer: It takes 8 days and 12 days for companies A and B to complete the task alone.

FYI! Jiangsu Wu Yunchao wishes you progress in your studies.

Suppose the daily progress of Company A is X and Company B is Y.

2 (2x+3y) is the total project progress.

2(2x+3y)-2x] y=[2(2x+3y) x]+1 simplified. 2（x/y)+1=6(y/x)

Let t=x y

Rule. 2t+1=6/t

Solution. t=so. Companies A and B complete their tasks separately.

2(2x+3y) x = 8 days.

2(2x+3y) y=12 days.

A: Completed in x days alone, B: Completed in y days alone.

2 x+3 y=1 2,(x+1) y+2 x=1, the solution is: x1=0, x2=1, x3=8, only x3=8 is in question, so y=12

1. Let the original number be 10a+b, and there is 10a+b=6(a+b)+3

10b+a=4(b+a)+9 ②

The simultaneous solution is a=7, b=5, and the original number is 75

2. If the original price is a and the current purchase price is b, then: selling price = a (1 + 15%) = b (1 + 25%)

Gain: the purchase price b=a(1+15%) (1+25%)=92%, that is, the purchase price is reduced by 1-92%=8%.

3. (1) Sales volume reduction = (x-60) 10 pieces.

2) Set the sales unit price to be x yuan, and the sales volume = 500 - (x - 60) 10 = 1100-10x

The solution is x = 80 yuan, and the sales unit price should be set at 80 yuan.

1. Let the two-digit single digit be a and the ten digit is b, which can be obtained from the question (10b+a) (a+b)=6, and the remainder of 3 (1)(10a+b) (a+b)=4, and the remainder of 9 (2), so from (1) 10b+a=6(a+b)+3, b=(5a+3), 4 (3).

10a+b=4(a+b)+9 from (2) gives 6a-3b=9 (4).

Replace (3) with (4) to get a=5, so b=7 and the two digits are 75

.1. Suppose the two-digit number is xy, and y is the single digit 10x+y=6y+3 10y+x=4x+9 without integer solution, this problem is not valid.

1. Set to xy, then there are, 6(x+y)+3=xy and 4(x+y)+9=yx

=>(x+y)=3, -=>xy=21, so the answer is 21.

2. Reduce by 10%.

3. (1) 10x pieces.

2) (60 + x) (500-10x) = 9000 solution x = 41

1.Let the number in the ten place be x and the number in the single place be y, and get: 6 (x + y) + 3 = 10x + y

After the reversal; 4(x+y)+9=10y+x Just solve this system of equations.

Set the length of the droop to x meters.

Available: 2x3=6=3(3-x)(2-x).

Solution: x1 = rounding).

A: The length of the tablecloth hanging down is 1 meter.

The length of the tablecloth hanging down is x meters, and the tablecloth area is 3 meters 2 meters = 6 square meters, because the tablecloth area is 3 times the table size area, so the table top area is 2 square meters.

Because the area of the tablecloth + the area of the tabletop = the area of the tablecloth, the equation is 3x 2 + (2-2x) x + 2 = 6

(x-2)(2x-1)=0

solution, x1 = 2, x2 = 1 2

Because the tablecloth is 2 meters wide, the sag length cannot be 2 meters, so x1 = 2 does not hold.

So, x=1 2

In the format of my homework.

Solution: If the length of the tablecloth is xm, then it can be obtained from the question: S table = (3-x) (2-x) (3-x) (2-x) * 3 = 3 * 2

Solution: x1=1, x2=4

Bring x=4 in, and x=4 doesn't fit the topic.

x=1

1) It is known that a(2,4), b(2,4), and point c are the intersection of the straight line ab and the y-axis. then c(0,4).

ab=2-(-2)=4 (because ab is parallel to the x-axis), so the area of AOB = ab*co 2=4*4 2=8

It's hard for me to forget.,Otherwise, I'll help you.。。。

This question is not a difficult question, it belongs to a basic situational discussion.

Solution: If there are x people in school A, then there are 2x people in school C and 14-3x people in school B.

When A2 is a person, then C4 is a person and B8 is a person.

When A3 is a person, then C6 is a person and B5 is a person.

When A4 is a person, then C8 is a person and B2 is a person.

Answer. In summary.

The number of students in school A has been increased.

then increase the number of people.

School A has 4+X

School C has 6+(2+2X) (the number of security guards after the increase in School C is twice that of School A).

School B has 5+(12-3x) [The total number of additional security guards in the three schools is 14, so 14-x- (2+2x)] has been added

x>=2

2+2x>=2

12-3x>=2

Solving inequalities yields 2=x=2 or x=3

When x=2.

School A has 4+2=6

School C has 6+(2+2*2)=12

School B has 5+(12-3*2)=11

When x=3, school A has 4+3=7

School C has 6+(2+2*3)=14

School B has 5+(12-3*3)=8

If school A adds x people, then school C adds 2x people (x is greater than or equal to 2), and school B adds y people, x+2x+y=14, 3x+y=14

x=x=3,y=5

x=4,y=2

These three cases.

2 (x + 4) = 2 x + 2 = z for 2 (x+4) = z

x+y+z=14 3x+y+2=14 3x=12-y x is greater than or equal to 2, y must be less than or equal to 6 and greater than or equal to 2, z must be greater than or equal to 6 and less than or equal to 10

When x=2, y=6, z=6

When x=3, y=3, z=8

When x=4, z=10, y=0 are not titled.

What a plan seems to be... The third year of junior high school is almost forgotten.。。。

Let x,y,z increase the number of people, 6+z=2x, so z=2x-6, x+y+z=14, so 3x+y=20

x>=2,y>=2,Exhaustive:

You can draw a coordinate or something

Let a add x people, x+2x+2 14, x=4, so. Tired yourself.

The first type: A2 people, B8 people, C4 people; the second type A3 people, B5 people, C6 people; the third type A4 people, B2 people, C8 people;

If a increases x people, then c is 2x, and the column x+y+2x=14(x 2), is it okay?

Untie; (1) When x is less than 100, y1=5000x, when x is greater than 100, y1=[5000-10(x-100)] x=-10x2+6000x, and x is less than 160. y2=5000x80 100x=4000x (2) is unsolvable by -10x2+6000x=1400000. From 4000x=14000000, x=350, answered.

I don't know much about the meaning of the question.

It's reduced by 10 yuan, and it becomes 4990, 4980 after more than 100. . . Is it?

3.The formulation of the problem does not seem to be clear.

5.A x B y

x+y）*1=9

18/x=(18-9)/y

x=6 y=3

6.Speed x in still water

66/(x+3)=48/(x-3)

x=826.A's x B's's y

x/y=2/3

2000 x + 1000 y = (1000 + 2000) 9 x process.

2000/x+1000/

2000+2000/3=1000/3x

8000/3=1000/3xx=8

3: Let the sugar content of A be x%, and the sugar content of B be y%.

x%*40:y%*77=2:3

1-x%)*40:(1-y%)*77=1:2...Ask for the answer.

If Shanghai and Yunnan are 300 kilometers apart, and the speed from Shanghai to Yunnan is set to be x km h, and the speed of B is y km h, x 2 - y 2 = 5

300/y - 300/x=1

Solve the system of equations x=

What and what ... The distance between Shanghai and Yunnan is 300 meters??? Nanking???