Junior high school winter vacation homework math problems, junior high school math winter vacation h

1.(2a+12)(a+3) 2= a 2+9a+18 when a=8, a 2+9a+18=64+72+18=1542Solution: Set the cost to x yuan.

1+50%）x×80%-x=20

Solution: x=100

3.Solution: If there are x boys, then there are (170-x) girls.

3x=7(170-x)

Solution: x=119 then there are 51 girls.

4.Solution: Set the plan to be completed in x days.

40x+20=50（x-1）-10

Solution: x=8 then there are 340 parts.

5 settings: walking time of teachers and students in each group: x, riding time of teachers and students in each group (33-5x) 55, car travel time x+(33-5x) 55, when (x+(33-5x) 55)*55=55*x*4+4*55(x-(33-5x) 55).

The time used is the shortest.

x=33/82

6. If you buy x bottles on the first day, you will buy 70-x on the second day

1. Suppose both days are more than 30 and less than 50.

70 3 80% = 168, the assumption is not correct.

2. Suppose you buy more than 50 bottles the next day.

3x+（70-x）×3×60%=183

x=, the assumption is incorrect.

3. Therefore, the number of bottles bought the next day is more than 30 and less than 50, so.

3x+(70-x) 3 80%=183x=25, that is, buy 25 bottles on the first day of class A and 45 bottles on the second day.

One, 1, s=(2a+12) (a+3) 2 12, when a=8, the original formula = (2 8 12) (8 3) 2 1 two, solution: set the cost of each piece x yuan, according to the meaning of the question:

1+50%)x×80%=x+20

Solution: x=100

Answer: (omitted).

Three, the solution: set up male x people, female (170-x) people, according to the meaning of the topic:

3x=7（170-x）

Solution: x=119

170-x）=51

Answer: (omitted).

Fourth, the solution: set x days to complete, according to the meaning of the question.

40x+20=50（x-1）- 10

Solution: x=8

5. Set: walking time for teachers and students in each group: x, riding time for teachers and students in each group (33-5x) 55, car travel time x+(33-5x) 55, when (x+(33-5x) 55)*55=55*x*4+4*55(x-(33-5x) 55).The time used is the shortest.

x=33/82

If you buy x bottles on the first day, you will buy 70-x on the second day

1. Suppose both days are more than 30 and less than 50.

70 3 80% = 168, the assumption is not correct.

2. Suppose you buy more than 50 bottles the next day.

3x+（70-x）×3×60%=183

x=, the assumption is incorrect.

3. Therefore, the number of bottles bought on the second day is more than 30 and less than 50, so 3x+(70-x) 3 80%=183x=25, that is, Class A buys 25 bottles on the first day and 45 bottles on the second day.

Analysis: The speed of the car is 55 kilometers per hour, and the car must travel for 1 5 hours or 2 5 hours, and it must not directly send the first batch of people to the end point (i.e. 3 5 hours), and if it takes 1 5 hours, the people on foot and the car cannot reach the destination at the same time.

The bus picks up 25 people when it departs, and the remaining 72 people walk, all take 2 5 hours, walk 2 kilometers, and travel 22 kilometers; When the car returned, it took another 1 3 hours to meet the 72 people.

It took another 2 5 hours to pick up the 25 people in the second group and the remaining 47 people on foot, and the car traveled another 22 kilometers, and the 47 people walked 2 kilometers, and the car returned to meet the 47 people in another 1 3 hours.

And so on, by the time of the 4th 2-5 hours, the last person is sent directly to the finish line. After testing, the last rider and the first three groups of riders can arrive at the same time.

Shared time: 1 3 3 + 2 5 4 = hours.

+9a+18 squared

a=203.Boys are x

170-x）*7=3x

x=119 girls: 51.

4.Let the part be x, and plan to be y

40y=x-20

x=340y=8

Parts: 340

Plan: 8 days will not.

1, ((a+12+a)(a+3)) is divided by 2, and when a is equal to 8, the value is 154

4.Set the plan to be completed in x days.

40x+20=50x-(50+10)

x=8, this batch of parts has 40x+20=340 (pieces), although there is only one question, but also give two points, hehe.

1:s=(a+12)(a+3)/2;1102: 100 yuan.

3: Male: 119. Female: 51.

4: 340; 8 days.

5: No. 6:57 yuan; 25 bottles, 45 bottles.

The fly flew a total of 15 miles, and the speed of the fly multiplied by the time it took for the fly to fly was the distance traveled by the fly, and the time it took for the fly to fly was one hour from the time the two boys began to meet. The second question is shown below.

1.Solution: From the question, the time for two boys to travel in opposite directions = 20 (10+10) = 1 hour, and since the time of the fly flight is the time when the two boys meet, the time for the fly to fly is 1 hour

The distance traveled by the fly is 15 1 = 15 (miles).

A: The flies flew a total of 15 miles

2 solution: set ignition and x hours.

The coarse ones burned x 3, and the thin ones burned x 1

The rest is 2 times.

So 1-x 3=2 (1-x 1).

1-x/3=2-2x

5x/3=1

x=so lit for hours.

If you give me 20 fortunes, I'll help you out.

The 5th power is 1, the 5th power of 2 is 32, the 5th power of 3 is 243, the 5th power of 4 is 1024, and the 5th power of the 5th power is 3125 ,...19 to the 5th power is 2476099;

and 3

1. The remaining 1 32 243 1024 3125 7776 16807 Too much of a vertical reed roll with a scientific calculator on a computer.

3, 2 and 3

1、 a=1/2 b=-1/3 c=-2

2. When a is greater than 0, 4a is greater than 3a

When a is less than 0, 4a is less than 3a

When a is equal to 0, 4a is equal to 3a

4、a=-2

b=-1c=1

d=3 a+b+c+d=1

Solution:1Because they are all absolute values, all three are 0A=1 2, B=-1 3, C=-2

2.When a=0, both are the same size; When a is greater than 0, 4a is greater than 3a; When a is less than 0, 3a is greater than 4a

3.I don't understand what the cubic c of b means.

4.These four numbers should be 1, -1, 2, -3, the sum of the four -1 or 1, -1, -2, 3, the sum of the four 1

1.Because the absolute values are positive, it is impossible for each formula to be negative, so every formula is equal to zero. Calculate a=1 2

b=-1/3 c=-2

2.If a is greater than 0, then 3a is less than 4a, if a is equal to 0, then 3a=4a, if a is less than 0, then 3a is greater than 4a

1: Because of DFAC

So angular c = angular fec

And because the angle c = the angle d

So the angle fec = angle d (the isotope angle is equal).

So db ec

2: Because of the EF CD

So the angle bef = the angle bcd

Angular EDC = Angular Fed

Because de ac

So angular DCA = angular EDC

So angular fed = angular dca

It is known that CD bisects the angle ACB (angle BCD = angle DCA) from this: angle BEF = angle fed

So: EF bisects the corner bed

Because a= b= c, a= b= c=60°, again.

Because 1= 2= 3=60°, 1= c, 2= a, 3= b, then ef bc, de ab, df ac