Math problems I don t understand! If you don t understand the math problem, ask the master to teach

It takes five and five elevenths of a day for 2 people to complete the project, then 11 60 people can complete the project every day, and it takes 6 days for 2 people to complete the project every day, then 1 6 C A and 2 people need six and two-thirds to complete the project every day, then 3 20 of the above three items for C A to complete the project every day and divide it by 2 to get 1 4 of the 3 people who can complete the project in one day, so the whole project can be completed in 4 days.

This set three unknowns, but not to solve the ternary system of equations, here is a clever solution, I believe your IQ can understand.

Let the work efficiency of A be 1 x, the work efficiency of B is 1 y, and the work efficiency of C is 1 z, and it takes five and five elevenths of a person to complete it, so 1 x+1 y=11 60 B and C 2 people need 6 days to complete, so 1 y+1 z=1 6 C A 2 people need six and two-thirds of a day to complete, so 1 z+1 x=3 20 The left and right sides of the three formulas are added respectively to obtain 2 (1 x+1 y+1 z)=1 2, so 1 x+1 y+1 z=1 4

Therefore, it takes 1 (1 x+1 y+1 z) = 4 for A, B, and C to complete the 3 people

Idea: Calculate that A, B and C each send two teams of people to complete the task, calculate the time and multiply it by 2, which is the time required for each team of A, B and C.

Time = Workload Efficiency.

Think of the total effort as 1

According to the above three ideas, the column formula:

A, B and C each send two teams of people to complete the task time = 1 [1 (5+5 11)+1 6+1 (6+2 3)=2

The time required for each team to be sent out = the time required for each team to complete the task * 2 = 2 * 2 = 4 days.

The second Wang Qi question.

You can set it to x grams, then.

1/5x-1/7x=80

2/35x=80

x=1400

So x = 1400 grams, which means that the cake is 1400 grams.

I don't understand the first question either.

The first problem is that there is one-fifth left, that is, one-half of the aged vinegar is one of the five-point resistance to the leakage difference when it is full. The old vinegar accounts for two-fifths of the full time, and how many kilograms depends on how many kilograms it is.

Solution: (1) Let y=k(x-3), and pass a(0, 4), so 4=-3k, k=-4 3

So y=-4 3 x+4

2) When t=2 seconds, op=2, and ob=3, so pb=13, so the circumference of obp=5+13.

3) When op=3, op=ob, obp is an isosceles triangle. When op=3, t=3 (sec).

5. It is known that the product of two factors is, one of the factors is, the other is the other, and the other is a decimal place.

6. The multiple of a number that is not equal to 0 must be larger than the original number. True or false. 7. Smoking is not only harmful to health, but also consumes energy in the production of cigarettes, and each person smokes 1 cigarette less per day, which can reduce kilograms of carbon dioxide emissions in a year.

If each of China's 100 million smokers smokes one less cigarette, how many tons of carbon dioxide can be reduced every year? (The number is kept as an integer) 130,000 tons.

8. In order to encourage residents to save water, the water supply company stipulates that each household shall be charged per yuan ton if the monthly water consumption exceeds 15 tons (including 15 tons), and if it exceeds 15 tons, the excess tonnage shall be charged at 5 yuan tons. Xiaoli's family paid a total of 28 yuan in water bills last month.

How many tons of water did Xiaoli's family use last month? 15 times yuan, 28-18 = 10 yuan, 10 divided by 5 = 2 tons, 15 + 2 = 17 tons.

4. What is the number of multiples of the ratio; What is the number less than 8 times? 2, 3 times plus 8—

You typed the wrong question! Peaches are more or less than half the size of bananas?

Apples: accounting for three-eighths of the total, that is, 400 * three-eighths = 150 kg I assume you have one more half here, that is, bananas have 1 part, peaches have 1 part + 400-150 = 250 (kg) 250 kg per portion) peaches are 100 * kg).

Banana is 100*1=100 (kg).

Calculation: 150 + 100 + 150 = 400 (kg) 150 100 = 1/2

So bananas are 100 kg, apples are 150 kg, and peaches are 150 kg.

What is the method in 6th grade?

Is a peach a half bigger than a banana?

Forehead... Sixth grade, will you be three dollars at a time?

When A catches up with B for the first time:

Time=400 (8-6)=200s

A stroke = 200 * 8 = 1600 meters.

B stroke = 1600-400 = 1200 meters.

When A catches up with B for the second time (at this time, A's velocity = 8-2=6, B's velocity = time = 400 (.)

The total time is: 200+800=1000s

A stroke: 800 * 6 = 4800 meters.

A total stroke = 1600 + 4800 = 6400

B stroke = 4800-400 = 4200 meters.

B total travel = 1200 + 4200 = 5600 meters.

When B catches up with A for the first time (at this point, A's velocity becomes 6-2=4, and B's velocity is time=400 (5-4)=400

Total time = 1000 + 400 = 1400s

A stroke: 400 * 4 = 1600 meters.

A total travel = 6400 + 1600 = 8000 meters.

B stroke = 5 * 400 = 2000 meters.

B head office code range = 5600 + 200 = 7600 meters.

Then B increases the speed to 5+, and A increases the speed to 4+

The time it takes for A to reach the end: (10000-8000) The time it takes for B to reach the end: (10000-7600) Therefore, Sock Oak is the winner. After B reaches the end point of Ruji, the distance that A is still missing is:

2000-4800 11*m.

1 Question (1) a=—x +2x —3x+1, b=—2—x+x a—2b

x³+2x²—3x+1—2（—2—x+x²）=—x³+2x²—3x+1+4+2x—2x²=—x³+—x+5

2) When x=—1 2, the original formula =—(—1 2) —2(—1 2)+5=1 8+1+5

Question 2 (1) 2) a=2, b=3

2a+b=2x2+3=7

The product of these two monomials = -2x to the 14th power y to the fourth power.

a=-x^3+4x^2-3x+1,b=x^2-x-21、（1）a-2b=-x^3+4x^2-3x+1-2*(x^2-x-2)

x^3+4x^2-3x+1-2x^2+2x+4=-x^3-2x^2-x+5

2)x=-1/2,a-2b=-x^3-2x^2-x+5

5 and 1 82, (1) The 2a + b power of the monomial -x to the 2nd power y and the 5a-8 of the 5a-b power y of 2x are the same terms.

then, 2a+b=5a-b, 5a-8=2

Therefore, a = 2 and b = 3

2）2a+b=2*2+3=7,5a-b=7,5a-8=2【(-x)^7+y^2】【(2x)^7+y^2】=(y^2-x^7)(y^2+x^7)

y^4-x^14

1. From the meaning of the title: a=-x +2x -3x+1

b=-2-x+x²

So a-2b = -x +2x -3x +1-2 (-2-x+x )=-x -x+5

When x=-1 2, a-2b=-x -x+5

2. Similar terms: refer to the terms containing the same letters, and the exponents of the same letters are also the same, such as -100ab and 14ab, 3x y

With -6x y, and so on, it is called a similar term.

Therefore, the -x (2a+b)y 2 and 2x (5a-b)y(5a-8) are the same terms as the title, and we can get: 2a+b=5a-b

2=5a-8

From the above two equations, it can be solved: a=2, b=3

A = 2, b = 3 generations of the monomial -x (2a+b)y 2 and 2x (5a-b)y(5a-8) yield:

The product of these two monomials is: (-x 7y 2)*(2x 7y 2)=-2x 14y 4

Quadratic functions have an axis of symmetry, from the quadratic function can be judged that the axis of symmetry is (m+1) 2, the following should determine which interval the axis of symmetry is in, ask the interval of [-1,2] in the question, then the axis of symmetry may be on the left of [-1,2], inside, the right of these three cases, you can get the solution by discussing them separately!

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