Solve the following math problems Solve the following math problems

200 (10-4) 33 pcs.

33 10 = 330 yuan 33 4 + 200 = 332 yuan.

A: At least 33 Chinese knots need to be added to the cost of making your own knots.

Hope it will help you, hope in time.

When you design x Chinese knots, you have 4x+200>10x, and it is more economical to make it yourself>.

When you set up x to make your own, it is cheaper to make it yourself.

10x=4x+200

x = so make at least 34. (Must be an integer, rounded up).

10x>4x+200

10x-4x>200

6x>200

x>200/6

x>100 3 is about 34 pieces, and it is relatively economical to make it yourself.

The cost of making x by yourself is more economical.

10x>4x+200

x=200/6=

So at least 34 of them should be done.

Set x pcs, 4x+200<=10x

x>=So it's good to buy at least 34.

Like the previous ones. Let x, and then the equation is solved.

The solution ideas of such problems are to set up unknowns, list one-dimensional one-time, two-dimensional one-time equations, etc.

∵sn=n^2*an

s（n-1）=（n-1）^2*a（n-1）∴sn-s(n-1)=an=n^2*an-（n-1）^2*a（n-1）

an*(n+1)*(n-1)=a(n-1)*(n-1) 2, and both sides are eliminated at the same time (n-1).

an*(n+1)=a(n-1)*(n-1) an a(n-1)=(n-1) (n+1) can only be found here, and the rest is substantiated.

a1=1/2，a2=1/6，a3=1/12,……an=1/n*（n+1）

1.This question is equivalent to Xiao Lin walking for 8 minutes first, and then Xiao Ming sets off from home. There is (70+60)x+60*8=870

Get x=32There are 123 trees planted on one side, and 122 of these 123 trees are 8m, that is, the length of this section of the road is 122*8=976

3.Liangliang turned out to have x sheets. (x-24)/x=,x=804.The speed of car B is x

km/x=48

Car A travels 40km per hour, and car B travels 48km5 per hourInitially, there were girls x people. [2(x-10)-9]*5=x-10x=15

The distance between the two places is x

km。(x/

x=7.Ballpoint pens are $ x each. 5(x+,x=

Xiao Ming brought 8x+ yuan.

Pick two of the easiest questions to answer. The same goes for other topics.

5.Solution: The original name of the boy x and the name of the girl y in the classroom are.

x=2(y-10)

5(x-9)=y-10

The solution is y=15

So there were originally 15 girls. Finished.

7.Solution: Let the unit price of the fountain pen be x yuan, and the unit price of the ballpoint pen will be y yuan, then x=y+

Solve x = so Xiao Ming brought the yuan.

1.One meter needs 5 16 * 8 = 5 2 yuan.

2.The boulevard has 3 8km * 16 = 6km.

Fill in the blanks 9, 16, 5 6

1. There are two situations in the first question:

1. If two cars depart from cities A and B at the same time, if A travels 264 kilometers when they meet, then let the distance between the two cities be x meters, and solve the equation according to the equation of time equality: (x-264) (1 12) = 264 (1 8).

2. If two cars depart from cities A and B at the same time, if B travels 264 kilometers when they meet, then let the distance between the two cities be x meters, and according to the equation of time equality: (x-264) (1 8)=264 (1 12) solve the equation: x=660

Second, first calculate the speed of the train, the time taken by the fire from the rear of the car into the cave to the rear of the car leaving the cave is 45-16 = 29 seconds, the length of the cave is 638 meters, that is to say, the train takes 29 seconds to walk a distance of 638 meters, the speed is 638 29 = 22 meters of seconds, the time taken by the train from the front of the car into the cave to the rear of the car into the cave is 16 seconds, then the length of the train is: 22 16 = 352 meters.

If the conditions are insufficient, please check and supplement.

Who traveled 264 kilometers when they met?

The train all goes into the cave and the distance is the length of the train.

From the time the train enters the cave to the time the train leaves the cave, the distance is the length of the cave.

The speed is constant, and the distance is proportional to the time.

The time ratio is 16:(45-16).

Train length: 638 (45-16) 16=352 meters.

1, solution: bus speed: 1 8 1 8

Truck speed: 1 12 1 12

Meeting time: 1 (1 8 1 12) 24 5 (hours) Bus speed: 264 24 5 55 (kilometers per hour) A and B distance: 55 1 8 440 (kilometers).

A: The distance between the two cities is 440 kilometers.

2. Solution: train speed = 638 meters (45-16) seconds = 22 meters seconds.

Train length = distance traveled by the train after all the trains have entered the cave = 22 meters * 16 seconds = 352 meters.

The first question, if the bus traveled 264 kilometers, the answer is as follows:

Passenger car speed * 8 = truck speed * 12, then passenger car speed: truck speed = 12:8, let the bus speed be 12k, truck speed 8k, then (12k + 8k) * meeting time = a, b two cities distance, known 12k * meet time = 264 km, then the distance between a and b two cities = 264 12 * 20 = 440 km.

And if the truck traveled 264 kilometers, the answer is as follows:

Passenger car speed * 8 = truck speed * 12, then bus speed: truck speed = 12:8, let the bus speed be 12k, the truck speed is 8k, then (12k + 8k) * meeting time = a, b two city distance, (the above is the same as above).

Knowing that 8K*Encounter Time = 264 km, then the distance between cities A and B = 264 8*20=33*20=660 km.

Question 1: When we met, which car traveled 264 kilometers?

Known conditions: (t:t) ponkan.

Average yield per mu Fruit bearing area Total yield Planting birds and households Gross output value Per capita income.

2009 mu (1) million tons (2) (3) (4).

2010 (8) (8) (7) million (6) (5).

Analysis: 1) Fruit-bearing area = total yield Average yield per mu, so in 2009 fruit-bearing area = 10,000 tons mu = 10,000 mu.

2) In 2010, the number of mandarin orange growers in the city reached 10,000, an increase of 10 compared with that in 2009; So in 2009, growers = 10,000 (1+10%) = 10,000.

3) Total output value = total output * selling price, so in 2009 total output value = 10,000 tons * yuan kg = 84.48 million yuan.

4) Per capita income = total output value of growers, so in 2009 per capita income = 84.48 million yuan 10,000 yuan = 7,040 yuan.

5) The average income of mandarin growers in 2010 was 2960 yuan higher than that in 2009, so the average income of Qingzhou households in 2010 = 7040 + 2960 = 10000 yuan.

6) Per capita income = total output value of growers, so in 2010 total output value = 10,000 yuan * 10,000 yuan = 132 million yuan.

7) Total output value = total output * selling price, so total output in 2010 = 132 million yuan kg = 120,000 tons

8) Fruit-bearing area = total yield average yield per mu, and the growth rate of fruit-bearing area and average yield per mu is the same, let the growth rate be x, then 2010 fruit-bearing area =, average yield per mu =, total yield = [10,000 t. Solution x = 25%, 2010 fruit area = 10,000 mu, average yield per mu = mu.

So the answer to the question:

1) How many acres of mandarin orange planting area can be fruited in 2009?

10,000 acres 2) How many tons of total output of mandarin oranges in the city in 2010 can reach at least?

120,000 tons. 3) Find the total area of fruit planting in the city in 2010.

In 2010, the city's ponkan fruit area reached sixty percent of the total area of fruit can be hung fruit, of which in 2010 the city's mandarin orange fruit area is 10,000 mu, so in 2010 the city's fruit planting area = 10,000 mu 10,000 mu.

In 2004, you can guess the planting area of mandarin orange with Hu hanging fruit:

10,000 mu = mu. Growers in 2004: 10,000 households.

In 2005, the growth rate of the fruit-bearing area and the average yield per mu of mandarin orange was x6400(x+1) 2-7040=29606400(x+1) 2=10000

x+1)^2=25/16

x+1= x= or x= rounded).

In 2005, the total output of mandarin oranges in the city can reach:

10,000 tons In 2005, the total planting area of fruit Zhaonian in the city that can hang fruit is mu.

Solution: a, o, and e are on the same straight line.

aoc+∠boc=180°

aoc=1 2 boc+15°

1/2∠boc+15°+∠boc=180°∠boc=110°

The ray oe is the bisector of the BOC.

boe=1/2∠boc=1/2×110°=55°

Because a, o, b three points are in the same straight line, so angle aoc + angle boc = 180 degrees, because angle aoc = 1 2 angle boc + 15 degrees, so 1 2 angle boc + 15 degrees + angle boc = 180 degrees, 3 2 angles boc = 180 degrees - 15 degrees = 165 degrees.

Angle BOC = 110 degrees, because OE is the bisector of angle BOC, so angle BOE = 1 2 angle BOC

1 2x110 degrees.

55 degrees.

+2+1=9

A: 240 boxes of apples, 80 boxes of pears, 40 boxes of oranges.

Pinions have (50) teeth.

There are two-thirds boxes of apples, two-ninths of pears, and one-ninth of oranges.

Looks like you've mistyped K as A.

1.If the domain is r, it is required that any x has [(k 2-1)x 2-(k+1)x+1 4]>0

If k 2-1=0, then k=1 or k=-1 Obviously, when k=-1, the above equation is always equal to 1 4>0

If k 2-1 is not equal to 0, then the quadratic function opens upwards and has no intersection with the x-axis, so there is (1)k 2-1>0

2) The function discriminant formula <0 can be solved by concatenation to obtain the range of k.

2.The range r requires that [(k 2-1)x 2-(k+1)x+1 4] can get (0,+infinity) All values are also classified and discussed.

If k 2-1=0, then k=1 or k=-1 is obviously satisfied when k=1.

If k 2-1 is not equal to 0, then the quadratic function opens upwards and has an intersection with the x-axis, so there is (1)k 2-1>0

2) Function discriminant" or =0 can be solved to obtain the range of k.

Note the difference between the two The second question is not concerned with the domain of the function f(x).

Width x, length x + thickness y

Bedspread: x (x+

x^2 + 4xy +y

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