[math problem] four numbers: 4, 4, 4, 4. Arbitrary addition, subtraction, multiplication and division, the result is equal to 10. Please solve the problem

[math problem] four numbers: 4, 4, 4, 4. Arbitrary addition, subtraction, multiplication and division, the result is equal to 10. Please solve the problem

(44-4)÷4＝10
(4 + 4 / 4) * radical 4 = 10

Xiao Ming uses 200N force to raise the weight of 150n object by 4m in 10s by moving the pulley. He asks how much work, power and mechanical efficiency he does

Part of Xiaoming's work is used to lift heavy objects, and the other part is lost on the friction of pulley. With the loss, there is efficiency, which is the ratio of useful power (lifting heavy objects) to total power (Xiaoming's work)
In this problem, Xiaoming's force is 200N and the weight is 150n, so the fixed pulley can be used to lift, and the friction of 50N is reasonable. If the movable pulley is used, it is not quite right, and the displacement of the movable pulley will be doubled, so I calculate the stable pulley
Xiaoming work: w = FS = 200x4 = 800j Xiaoming power (mechanical input power): 800 / / 10 = 80W
Work done by pulley block on object: w = FS = 150x4 = 600J, power (mechanical output power): 600 / 10 = 60W
Mechanical efficiency: 60 / 80 = 75%

In the arithmetic sequence {an}, the tolerance d = 2, an = 11, the first n terms and Sn = 35

In ∵ arithmetic sequence {an}, the tolerance d = 2, an = 11, the first n terms and Sn = 35 ∵ A & nbsp; 1 + (n − 1) × 2 = 11 (1) Na1 + n (n − 1) 2 × 2 = 35 (2) (3 points), (1) × n - (2), n 2-12n + 35 = 0  n = 5 or 7 (3 points) n = 5A1 = 3 or n = 7a1 = - 1 (2 points)

[urgent!] from the beginning of the movement, through s, 2S, 3S The time ratio of NS displacement is T1 ∶ T2 ∶ T3:... = 1: radical 2: radical 3:
We need a specific calculation process
Thank you

Let the first displacement be s, the second is 2S, and so on
s=1/2a(t1)2
So T1 = under the root sign (2S / a)
T2 = under root sign (4S / a)
and so on
Finally, the conclusion is obtained by simplifying T1 as the standard
We also have this assignment today. I just pushed it out. It should be right. Anyway, my final conclusion is right. I don't know if you can understand it

For any natural number, first sum all its digits, then multiply the sum by 3 and then add 1. Repeat this operation for many times, and the operation result will eventually get a fixed number r
Q: why is r 13?
Is there any other way?

These two pasting giants
Is the answer to such a simple question so ink
Because the landlord's problem is a number * 3 + 1. Then you can make an equation of primary school difficulty
Let X be the number of bits and y be the number of tens, then (x + y) * 3 + 1 = x * 10 + y, and 7x-2y = 1 (both X and y should be natural numbers less than 10), then x must be 1, so y is 3
It's not strict enough, but most people can understand it!

If no matter what the value of K is, x = - 1 is always the solution of the equation (KX + a) / 2 - (2x-bk) / 3 = 1 about X, try to find the value of A.B

Replace - 1 with:
(-K+A)/2-(-2-BK)/3=1
0.5a-0.5k+2/3+bk/3=1
(b/3-0.5)*K+0.5a=1/3
Because it has nothing to do with X and K
b/3-0.5=0
0.5a=1/3
therefore
b=1.5
a=2/3

On the number axis, point a represents - 4. If the origin is moved one unit length in the negative direction, then the number represented by point a on the new number axis is ()
A. -2B. -3C. -4D. -5

From - 4 + 1 = - 3, the number represented by point a on the new number axis is - 3

Math question × 1 (150 points for correct answer)
As shown in the figure, there are four points a, B, C and D on the circle with a diameter of about 2.8 cm, and the quadrilateral ABCD is a square with a side length of 2 cm. EF is an arc on the circle with point a as the center and line segment AC as the radius. Calculate the area and perimeter of the shadow part
As shown in the figure, there are four points a and D on the circle with a diameter of about 2.8 cm, and the quadrilateral ABCD is a square with a side length of 2 cm, e

As shown in the picture, what about the picture?

The following statement is correct ()
A. If AB > 0, then a > 0, b > 0. B. If AB = 0, then a = 0, B = 0
C. If AB > 0 and a + b > 0, then a > 0, b > 0. D. A is any rational number, then - a × a < 0
Four unequal integers a, B, C, D, their product ABCD = 9, then the sum of these four numbers is ()
A.0 B.4 C.9 D.3

c. In the first question a, AB is less than zero at the same time, only one in B is equal to zero, and a = 0 in D
The second questions are 1, - 1,3 and - 3 respectively. There is no difference in ranking

(minus 36) times (half minus two-thirds plus 0.75)

(minus 36) times (half minus two-thirds plus 0.75)
=（-36）*（1/2-2/3+3/4)
=(-36)*(6/12-8/12+9/12)
=(-36)*7/12
=-21