Sequence 2, - 11101, - 100110001 A general formula of is?

Sequence 2, - 11101, - 100110001 A general formula of is?

(-10)^(n-1)+(-1)^(n-1)

If the parabola C1: y = x + 1 and the parabola C2 are symmetric about the X axis, what is the analytical formula of the parabola C2?

The vertex coordinates of parabola C1 are (0,1)
The vertex of parabola C2 and C1 are symmetric about X axis
So, the vertex coordinates of C2 are (0, - 1)
The opening direction of C2 is opposite to that of C1
Therefore, the analytical expression of parabola C2 is
Y = - X-1

Y is a cylinder with a diameter of 48 mm and a height of 3 mm. What is the weight of this cylinder?

The density of silver is 10.5 g / cm3
2.4x2.4x3.14x0.3x10.5 = 56.97g

(1/11+1/21+1/31++1/41)*(1/21+1/31++1/41+1/51)-(1/11+1/21+1/31+1/41+1/51)*(1/21+1/31+1/41)=?

Let 1 / 21 + 1 / 31 + 1 / 41 = a, the original formula = 1 / 11a + a ＾ 2 + 1 / 51A + 1 / 11 * 1 / 51-1 / 11a-1 / 51a-2 = 1 / 11 * 1 / 51 = 1 / 561

What function is derived y = LNX, that is, the derived function is y = LNX, what is the original function

y=xlnx-x+C

How much air is needed for full combustion of natural gas per cubic meter?

The main component of natural gas is methane. 3 cubic meters of oxygen is needed for complete combustion of each cubic meter of methane. The oxygen content in air is 21%, so the air demand is (3 / 0.21) = 14.3 cubic meters

If we define a ⁃ B = 5 * A-2 * B, where a B is natural number calculation 10 ⁃ 6 8 ⁃ 5 ⁃ 7
In addition, it means
What does the mark represent?

10※6=5*10-2*6=50-12=38
8※(5※7) =8※（5*5-2*7）=8※11=5*8-2*11=18
You're in grade one. There's no need to know the meaning of ⁃ as long as you know that a ⁃ B = 5 * A-2 * B, just like our formula, you can calculate the number of generations

Triple integral to find the volume enclosed by z = √ (x ^ 2 + y ^ 2) and z = 6-x ^ 2-y ^ 2,

The volume of solid can be expressed by triple integral, v = ∫∫∫∫ dxdydz. The integral region is the solid surrounded by z = 6-x ^ 2-y ^ 2 and z = √ x ^ 2 + y ^ 2. The equation of two surfaces is solved simultaneously, and z = 2 is the interface of two surfaces

How many light years is the nearest star to the earth?

4.3 light years

Is Zu Chongzhi really calculating pi?

Attention! The academic circles are still debating what method Zu Chongzhi used to calculate pi. Liu Hui's cutting circle technique is his. As for whether Zu Chongzhi used it or not, there is no final conclusion. We just guess that he may use it
"Zu Chongzhi's research work on PI and other important contributions are recorded in the book of Zhuozhu. Unfortunately, this rich mathematical monograph was lost later. Therefore, Zu Chongzhi's method of calculating pi is no longer available."
Relevant information:
Liu Hui's circle cutting technique
When solving such problems as circumference, area and volume of a circle, PI is often used. PI can be expressed as an infinite non cyclic decimal
　　3.1415926535…… .
It has been proved in modern mathematics that Pi is a number that can not be calculated by finite times of addition, subtraction, multiplication and division, and opening the power, which is the so-called "transcendental number"
Before the Han Dynasty in China, the commonly used PI was "three days diameter one", that is, the value of π = 3. Obviously, this value is very rough, and it will cause great errors in calculation. With the development of production and science, "three days diameter one" can not meet the requirements of accurate calculation. Therefore, people began to explore more accurate PI, At the beginning of the second century, Zhang Heng, an astronomer of the Eastern Han Dynasty, used ≈ 3.1466 in Lingxian and ≈ 3.1622 in the formula of spherical volume. Wang Fan (228-266), a Wu people in the Three Kingdoms period, used ≈ 3.1556 in the theory of armillary sphere, Compared with the ancient ratio, the accuracy is improved, and the pI value is the earliest record in the world. However, most of these values are empirical results and lack of solid theoretical basis. Therefore, it is still very important to study the scientific method of calculating pi
Liu Hui, an outstanding mathematician in the Wei and Jin Dynasties, made a very outstanding contribution in calculating the square quotient of PI. When he annotated the ancient mathematical masterpiece nine chapter arithmetic, he correctly pointed out that "three week diameter one" is not the value of PI, but actually the ratio of the circumference and diameter of a regular hexagon in a circle, After in-depth study, Liu Hui found that when the number of sides of a regular polygon inscribed in a circle increased infinitely, the circumference of the polygon approached the circumference of the circle infinitely, so he created the circle cutting technique, which established a very strict theory and perfect algorithm for calculating the circumference ratio and the area of the circle
The main content and basis of Liu Hui's circle cutting technique are as follows
First, the length of each side of a regular hexagon inscribed in a circle is equal to the radius
Secondly, according to the Pythagorean theorem, the length of each side of a circle inscribed with a 2 - π - regular polygon can be obtained from the length of each side
Third, from the length of each side of the inscribed regular L-edge, the area of the inscribed regular L-edge can be obtained directly. As shown in the right figure, the area of the quadrilateral oadb is equal to half of the product of the radius od and the length ab of the regular L-edge
Fourth, the area of circle s satisfies the inequality
　　S2n