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hello everyone!my name is**.i'm fourteen years old this year,i study in yingxingjiu foreigh language school.my student number is 47.i have lot's of hobbies,and i like play badminton very well.by the w...

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Regional Adjustment Permitted to Solve Population Problem
The population structural contradiction in China is growing with every passing day and the next 15 years will be crucial for China to tackle this problem. The population policies in China will remain unchanged and there will be only some supplement and improvement that allows the regional readjustment to solve the problems, says the Legal Daily.
The "One-child policy" China adopted in the late 1970s and the early 1980s has effectively controlled nation's total population and reduced newborn babies by 300 million. The childbirth level has dropped to that of the developed countries. Consequently, the problems such as the gender disproportion of newborn babies and aging emerged.
The gender disproportion of newborn babies began to rise from the middle of 1980s. The number climbed from 108.47 in 1980 to 116.92 in 2000, i.e. nearly 117 boys were born as against an average of 100 girls, which largely deviated from the normal range of 103 to 107.
The population structural contradiction is also illustrated by the growing aging process. Currently, there are 88 million senile citizens over 65 years of age, which takes up 7 percent of the total national population. It is estimated that the aged population above 65 will make up 11.8 percent of the nation's total by 2020, and 25 percent by the mid 21 century.
The emergence of the population structural contradiction changed the regional childbirth policy. It is reported that Shanghai municipal government has abolished the double material rewards to the couple who does not bear child and ease the conditions for the one who wants to have a second child.
Yu, Xuejun, director of the Policy and Regulations Department of National Population and Family Planning Commission, said the change Shanghai has made is a regional readjustment and within the nation's general population policies. It does not overrun the national principle, the basic "one-child policy" for family planning.
The next 15 years starting from now will be the crucial period for China's population development, pointed out Yu Xuejun. All the negative influences foreseen and unforeseen when stipulating "one-child policy" will come to appear. In this 15-year-long crucial period, China's population will remain unchanged and there will be only some supplement and improvement. China's population will climb to its peak of 1.6 billion by 2055. But if every couple has a second child, that peak will arrive 10 years earlier. As long as we maintain the current childbirth rate, the nation's total population will be kept within 1.5 billion by 2035.

If the area of a rectangle is increased by 20 square centimeters, the area of the original rectangle will be () square centimeters

The original area of the rectangle is (40) square centimeters
Suppose length x width y
The increased area is
(x+x/4)(y+y/5)
=3xy/2
3xy/2-xy=20
So xy = 40

It is known that the intersection point of the line y = 3 / 2X-4 and y = - 4 / 3x + K / 3 is in the fourth quadrant, and the value range of K is obtained
To explain in detail Process Explain

According to the meaning of the title,
3/2X-4=-4/3X+K/3
The solution is x = 24 / 17 + 2K / 17
Substituting x = 24 / 17 + 2K / 17 into y = 3 / 2X-4
The solution is y = 3K / 17 - 32 / 17
Because y < 0, x > 0
So (3K / 17 - 32 / 17) < 0
（24/17 + 2K/17）＞0
The solution is - 12 ＜ K ＜ 32 / 3

What is the derivative of F (x) = X-1 / x + 1? What is the derivative formula of fraction

1 + 1 / (square of X + 2x + 1)

The area ratio of the overlapped part and the shadow part in square a is 3:13, and the area ratio of the overlapped part and the shadow part in square B is 1:2. Find the area ratio of square a and square B

Area of square a × 33 + 13 = area of square B × 11 + 2 area of square A: area of square B = 13:316 = 16:9 A: the area ratio of square a to square B is 16:9

If f (0) = 0 and f (x + 1) = f (x) + X + 1, then the expression of F (x) is

F (x) is a quadratic function, Let f (x) = ax ^ 2 + BX + C. according to f (x + 1) = f (x) + X + 1, f (0) = 0, let x + 1 = 0, then x = - 1, Let f (0) = f (- 1) + - 1) + 1 = f (- 1), that is, f (- 1) = 0; let x = 0, then f (1) = f (0) + 0 + 1, that is, f (1) = 1, substitute f (- 1), f (0), f (1) into f (x), there is A-B + C = 0C = 0A + B + C = 1 solution

K take______ The quadratic trinomial 4x2 - KX + 3 is a complete square

∵-kx=±2x×3，∴k=±43．

Why A3 + A4 + A5 = (A2 + a3 + A4) & Q?

Is an equal ratio sequence? In the equal ratio sequence, an = a (n-1) * q, so A3 = A2 * q, A4 = A3 * q, A5 = A4 * q, the two sides add up to get your equation

As shown in the figure, point D is a point on the hypotenuse ab of RT △ ABC, de ⊥ BC is in E, DF ⊥ AC is in F, if AF = 15, be = 10, then the area of quadrilateral decf is______ ．

If ∵ DF ⊥ AC, de ⊥ BC, ∵ DFC = ≁ C = ≁ Dec = 90 ° and ∵ quadrilateral dfce is a rectangle, it is easy to know that DF ∥ BC, then ∵ ADF = ≁ B, AFD = ≁ DEB, ∩ ADF ∽ DBE, ∩ dfbe = afde, i.e. de · DF = AF · be = 150, ∩ s rectangular dfce = de · DF = 150, i.e. the area of quadrilateral dfce is 150

Self introduction The content is: my name is * *, 14 years old, in yingxingjiu foreign language experiment school, student number is 47. My hobby is playing badminton. My favorite colors are blue and black.