What is the unit of length in the machinery manufacturing industry? What is the unit of length in the Silk Road For example, how much silk is a centimeter and how much silk is a millimeter

What is the unit of length in the machinery manufacturing industry? What is the unit of length in the Silk Road For example, how much silk is a centimeter and how much silk is a millimeter

One millimeter is equal to 100 threads

Read the following words, contact the actual life, experience the meaning
"Take a good look, dear child," said the father kindly, "there is more than one way to the square. Life is the same. If you find that you can't get to your destination by this way, you can try another way!"

Square is the goal and ideal in our life
Meaning: when the direction we choose can't achieve our goal, don't be discouraged and desperate. We can also choose other directions and adopt other methods. We should persevere in our ideals. When we encounter difficulties, we should think calmly and have ways to solve them

Decomposition of polynomial XY (XY + 4) - 2 (x + y) (x ^ 2-xy + y ^ 2) by two methods

xy(xy+4)-2(x+y)(x^2-xy+y^2)
= x^2y^2 + 4xy -2(x^3+y^3)
= x^2y^2 + 4xy - 2x^3 - 2y^3
= (x^2y^2 - 2y^3) + (4xy - 2x^3)
= y^2 (x^2 - 2y) + 2x(2y - x^2)
= y^2 (x^2 - 2y) - 2x(x^2 - 2y)
= (x^2 - 2y)(y^2- 2x)
xy(xy+4)-2(x+y)(x^2-xy+y^2)
= x^2y^2 + 4xy -2(x^3+y^3)
= x^2y^2 + 4xy - 2x^3 - 2y^3
= (4xy - 2y^3) - (2x^3 - x^2y^2)
= 2y(2x - y^2) - x^2 (2x - y^2)
= (2x - y^2) (2y- x^2)

Second grade 10-10000 integer addition and subtraction

Given that the sum of solutions X and y of the system X − y = 2aX + 3Y = 1 − 5A is a positive number, the range of a is obtained

X − y = 2aX + 3Y = 1 − 5a, by adding the two equations, we get 2x + 2Y = 1-3a, that is, x + y = 12 (1-3a), ∵ the sum of solutions X and y of the system of equations x − y = 2aX + 3Y = 1 − 5A is a positive number, ∵ 12 (1-3a) > 0, a < 13

It is known that a = 1 / 2, B = 1 / 3, C, where ABC is three three digits, which are composed of nine digits 123456789,
To make this equation true, what should ABC be?

There are four sets of data to meet the following requirements:
1.192,384,576
2.219,438,657
3.273,546,819
4.327,654,981.

It is known that f is the right focus of hyperbola x ^ 2 / A ^ 2-y ^ 2 / b ^ 2 = 1, and the line L passing through point F with slope of 3 is tangent to circle x ^ 2 + y ^ 2 = B ^ 2, then the eccentricity of hyperbola is zero

Hyperbola x ^ 2 / A ^ 2-y ^ 2 / A ^ 2-2-y ^ 2 / b ^ 2 / b ^ 2 = 1 right focus ({(a \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\b & # 178;) - 360a & # 178; = 0, a = 3b, e = √ (1 + B & # 178 / / A & # 178;) = √ 10 / 3

Mathematics, comparative size ~ to answer the process in detail!
(1) √ 2 and & # 179; √ 3
(2) - 4 √ 3 and - 3 √ 5

In the first group, two numbers are to the sixth power at the same time. The former is 8 and the latter is 9, so three times follows three times, which is bigger
In the second group, compared with the absolute value, the two numbers are squared at the same time. The former is 48, and the latter is 45. The former is larger, but the two numbers are negative, so the former is larger in absolute value and smaller in negative sign
Two groups of numbers, are the following number is larger

It is known that a root of the quadratic equation AX2 + BX + C = 0 (a ≠ 0) is 1, and a and B satisfy B = a − 2 + 2 − A-3. The root of the equation 14y2-c = 0 about y is obtained

∵ a, B satisfy B = a − 2 + 2 − A-3, ∵ A-2 ≥ 0, 2-A ≥ 0, ∵ a = 2, substitute a = 2 into b = a − 2 + 2 − A-3, B = - 3, ∵ a root of the univariate quadratic equation AX2 + BX + C = 0 (a ≠ 0) is 1, ∵ a + B + C = 0, and a = 2, B = - 3, ∵ C = 1, ∵ equation 14y2 = 1 about y, the solution is y = ± 2

Addition and subtraction of rational number (- 15) + (- 6) (- 2 and 1 / 4) + (2.25) (- 1 / 5) + 0

(-15)+(-6)
=-（15+6）、
=-21
(- 2 and 1 / 4) + (2.25)
=-2.25＋2.25
=0
(- 1 / 5) + 0
=-1 / 5