A cylindrical water pipe with an inner diameter of 30 cm and a water flow velocity of 4 m / s, how many cubic meters of water can this water pipe flow in 2 minutes?

A cylindrical water pipe with an inner diameter of 30 cm and a water flow velocity of 4 m / s, how many cubic meters of water can this water pipe flow in 2 minutes?

Hello:
Radius: 30 △ 2 = 15 (CM) = 0.15 (m)
Flow: 3.14 × 0.15 × 0.15 × 4 × 2 × 60 = 33.912 (M3)

If two infinitesimals are not equivalent, just like cosx-1 and SiNx, if they are subtracted, can they be replaced by the sum of squares of X?

I tell you with the most accurate language: only in some special cases, can. 1. Usually only in the multiplication and division factor can use the Equivalent Infinitesimal Substitution. 2. Special case refers to: two subtraction formula is the same order and equivalent infinitesimal. As you ask why not? In fact, it can be demonstrated, you should learn

6 × () = 3 / 8 × () = 9 / 8 × 4 / 8 = 1

6 × (1 / 6) = 3 / 8 × (8 / 3) = 9 / 4 × 4 / 9 = 1
You can ask if you don't understand! Thank you!
I wish you progress in your study

How to calculate 5.3 * 3.6 + 4.8 * 0.35 with simple method

5.3*3.6+4.8*0.35
=5.3*3*1.2+1.2*4*0.35
=(5.3*3+4*0.35)*1.2
=（15.9+1.4）*1.2
=17.3*1.2
=20.76

Two common point forces F1 = 5N, F2 = 4N, the included angle between the two common point forces is 120 degrees. The magnitude and direction of the resultant force F of the two common point forces are obtained by graphic method

It's 21n
I'm only one level and can't pass pictures
If you find a ruler, 1cm is a unit, which means 1n
Draw two lines~
Then, translate one line to the other line arrow

What is the simple formula of 16.8 △ (2.1 + 0.4)?

=16.8÷2.5
=16.8÷(10÷4)
=16.8÷10×4
=1.68×4
=6.72

Find the rules and fill in the numbers 1,4,9, (), (), 36

1x1=1
2x2=4
3x3=9
4x4=16
5x5=25
6x6=36
So fill in the numbers 1, 4, 9, (16), (25), 36

A two digit number is a prime number. The number of one digit is still a prime number after exchanging its position with the number of ten digits, and the number of one digit is different from the number of ten digits
How many are there? What are the numbers?

First of all, consider the number of bits larger than ten bits (because after swapping the position, it becomes another number)
The sum of tens and tens must be prime numbers, 1,3,5,7,9, and the number of tens cannot be 5. So the sum of tens and tens can only be 1,3,7,9
The number that satisfies this basic requirement is 3 + 2 + 1 = 6
So we can directly enumerate. 13 17 satisfied and 19 unsatisfied
37 satisfied 39 unsatisfied
79 satisfied
A total of 4 * 2 = 8 numbers meet 13 17 37 79
31 71 73 97

Let f (x) = 1 x ∈ [1,2]; f (x) = X-1 x ∈ (2,3] g (x) = f (x) - ax, X ∈ [1,3], where a ∈ R, note the maximum value of G (x)
Let f (x) = 1 x ∈ [1,2]; f (x) = X-1 x ∈ (2,3]
G (x) = f (x) - ax, X ∈ [1,3], where a ∈ R, the difference between the maximum and minimum of G (x) is h (a)
Finding the analytic expression of function H (a)

When x ∈ [1,2], G (x) = - ax + 1 is a monotone function of X;
When x ∈ (2,3], G (x) = x-1-ax = (1-A) X-1 is a monotone function of X
The maximum and minimum of G (x) can only be obtained in G (1) = - A + 1, G (2) = - 2A + 1, G (3) = - 3A + 2
From G (1) - G (2) = a = 0, G (1) - G (3) = 2a-1 = 0, G (2) - G (3) = A-1 = 0, corresponding to a = 0, a = 1 / 2, a = 1
Then, when a ∈ (- ∞, 0), G (3) > G (2) > G (1), H (a) = 1-2a;
When a ∈ [0,1 / 2], G (3) > G (1) > G (2), H (a) = 1-A;
When a ∈ [1 / 2,1], G (1) ≥ g (3) > G (2), H (a) = a;
When a ∈ [1, + ∞), G (1) > G (2) ≥ g (3), H (a) = 2a-1

Stop and sit in the maple forest at night

Park and sit in maple forest at night, frost leaves are red in February flowers
If everyone gives a little love, the world will be full of love