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A practical problem To build a road, one sixth of the whole road has been built for the first time, and 15% of the whole road has been built for the second time. This is 6 kilometers away from the midpoint of the road. How long is the road?
6÷（1/2—1/6—15%）=360/11
A math problem, the problem is as follows (application problem)
It is reported that the annual output of plastic bags in the United States is about 90 billion. According to the recovery rate of 4-5 (four fifths), 210000 tons of greenhouse gas emissions and 136000 tons of waste can be reduced every year. However, the monthly consumption of plastic bags in China is about 90 billion. According to the recovery rate of 2-5 (two fifths), how many tons of greenhouse gas emissions and waste can be reduced in China every year?
It can be seen from the meaning of the title:
The annual amount of plastic bags recovered in the United States is exactly the same as that in China in two months, from 12 months a year to 12 months a year
In our country, it can be used every year
Reducing greenhouse gas emissions: 21 * 6 = 1.26 million tons
Waste reduction: 136 * 6 = 816000 tons
An engineering team contracted a demolition project in the process of shantytown reconstruction in our city. The original plan was to demolish 1250m2 every day, because of insufficient preparation, the demolition was reduced by 20% on the first day. From the second day, the engineering team accelerated the demolition speed, and demolished 1440m2 on the third day Days of demolition area than the previous day increased by the same percentage, this percentage
Solve by equation
For a project, Party A will complete it in 24 days, Party B will complete it in 20 days, and Party C will complete it in 30 days. Party A, Party B, and Party C of the county will cooperate to complete the project, and the project cost is 24000 yuan. According to the quantity of the project, how many yuan are the teams? Use the equation to solve the problem
Suppose three people cooperate to complete the project in X days, then x / 24 + X / 20 + X / 30 = 1 x = 8, 8 / 24 = 1 / 3 = 5 / 15, 8 / 20 = 2 / 5 = 6 / 15, 8 / 30 = 4 / 15, team a should pay 24000 * 5 / 15 = 8000 yuan, team B should pay 24000 * 6 / 1
It is proved that the length of two tangents leading from a point outside the circle is equal, and the line between the center of the circle and this point bisects the angle between the two tangents
It's better to take pictures,
Using the congruence of triangle Pao and triangle PbO (congruence judgment of right triangle: hypotenuse and right edge theorem), you can prove the conclusion you need
Discriminant of roots of cubic equation with one variable
0=ax^3+bx^2+cx+d
The number of solutions of is expressed by the formula of a, B, C, D
And explain~
x1=1/6/a*(36*c*b*a-108*d*a^2-8*b^3+12*a*(12*c^3*a-3*c^2*b^2-54*c*b*a*d+81*d^2*a^2+12*d*b^3)^(1/2))^(1/3)-2/3*(3*c*a-b^2)/a/(36*c*b*a-108*d*a^2-8*b^3+12*a*(12*c^3*a-3*c^2*b^2-54*c*b*a*d+81*d^2*a^2+12*d...
What is the land area of China? Which is the largest in the world?
Land area: 9.6 million square kilometers
Ocean area: 3.5 million square kilometers
The first is Russia: 17.07 million square kilometers
Second, Canada: 9.97 million square kilometers
The third is China
Fourth, the United States has 9.36 million square kilometers
Coulomb's formula
The unit of charge is Q, (c) Coulomb
The calculation of current: I = q / T
I -------- current (a)
T -------- time (s)
Q -------- quantity of electricity (c)
September 2004 is Friday. From that day forward, what day is 100 days?
How to do such a similar problem?
September 10th
September 10, 2004 is Friday. What day is 100 days after that?
Since September 10, 2004 (it's Friday), every seven days it's Friday,
More than 2, that is, 100 days after this day, and more than 2 days after 14 weeks,
Two more days after Friday is Sunday
September 10, 2004 is Friday, and 100 days after that is Sunday
The law of the method of quoting the common factor and a problem of using the method of quoting the common factor
fast
The law of common factor Ma + MB + MC = m (a + B + C)
Question 2Mn ^ 2 + 4m ^ 2n
=2mnxn+2mnx2m
=2mn(n+2m)
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