There are 10 different natural numbers, the sum of which is equal to 80. How many odd numbers are there in these 10 natural numbers?

There are 10 different natural numbers, the sum of which is equal to 80. How many odd numbers are there in these 10 natural numbers?

∵0＋2＋4＋6＋8＋10＋12＋14＋16＝72
The maximum number of even numbers is 9, and the sum of two odd numbers is even
At least two odd numbers

How many natural numbers are less than 1000 and the sum of each digit is equal to 6

006
015
024
033
042
051
060
one hundred and five
one hundred and fourteen
one hundred and twenty-three
one hundred and thirty-two
one hundred and forty-one
one hundred and fifty
two hundred and four
two hundred and thirteen
two hundred and twenty-two
two hundred and thirty-one
two hundred and forty
three hundred and three
three hundred and twelve
three hundred and twenty-one
three hundred and thirty
four hundred and two
four hundred and eleven
four hundred and twenty
five hundred and one
five hundred and ten
six hundred

(100-45) * (1-1 / 56) simple

(100-45)*(1-1/56)
=55*55/56
=(56-1)*55/56
=55-55/56
=54 and 1 / 56

The function f (x) = x ^ 3-x satisfies the ξ of Lagrange's differential mean value theorem on [0,2]=
Please write a step, thank you, thank you!

From F (x) = x & # 179; - x,
∵f（0）=0,f（2）=2³-2=6.
f′（x）=3x²-1
f′（ξ）=[f（2）-f（0）]/（2-0）
=3
That is 3x & # 178; - 1 = 3
ξ=x=2√3/3

In the hospital, there is an oxygen cylinder with a volume of 10 cubic decimeters, which contains oxygen with a density of 2.5kg/m3
A.2KG/M^3 B.2.1KG/M^3 C.2.2KG/M^3 D 2.5KG/M^3

v1=10dm3=0.01m3
The original mass M1 = ρ 1v1 = 2.5kg/m3 × 0.01m3 = 0.025kg/m3
When 5g is removed, the mass becomes smaller, M2 = 0.025kg-0.005kg = 0.022kg
However, the volume remains unchanged, V2 = V1 = 0.01m3
So ρ 2 = m2 / V2 = 0.02kg/0.01m3 = 2kg / m3
So choose a

Definition: a ⁃ B = (a-b) divided by (1 + AB) is a kind of operation within the range of rational number, to find the value of (- 2) ⁃ 3

(-2)※3=((-2)-3)÷（1+（-2）×3）
=-5÷-5
=1

What is the geometric meaning of triple integral

First of all, generally speaking, the physical meaning of triple integral is the volume mass of a solid, not the geometric meaning
Now I will introduce to you why triple integral can be understood as solid volume mass
I've been in for half an hour
Here cannot upload the picture, goes to my space to look, I give the website address
I've been in for half an hour

The ruler with only three scale lines has a 9cm long ruler. Please determine the position of the three scale lines on the ruler so that the ruler with only three scale lines can measure all the whole centimeter line segments from 1 to 9cm. Please design at least three schemes on the ruler shown below

As shown in the figure, any one of the four methods can meet the requirements

It is the first time in the world to calculate the value of pi to the seventh digit after the decimal point
What's wrong
one

In nine chapters on arithmetic, Zu Chongzhi calculated pi to the seventh digit after the decimal point for the first time in the world
It should be people, not books

The surface area of solid surrounded by paraboloid x ^ 2 + y ^ 2 = AZ and cone z = 2A - √ (x ^ 2 + y ^ 2)

If z = 2A - √ (x ^ 2 + y ^ 2), then Z