A and B are two sets, Difference set? Is it the rest of a minus B?

A-B = a - (a to b)
It means to remove the common elements of a and B in a

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1. For sets a and B. define the operation For sets a and B, define operations: a x B = {x | x = a * B, a ∈ a, B ∈ B}, C = a x B, let a = {1,2,3,4,}, B = {3,6,9} (1) If d = {x | x = 2k-1, K ∈ Z, X ∈ C}, the sum of elements in each subset of D is M1, M2, m3 , MK, M1 + M2 + m3 + mk ==== jiulang1989。 Second question?
2. Define set operation: a * b = {ZLZ = XY (x + y), X ∈ a, y ∈ B}. Let a = {0,1}, B = {2,3}, then the sum of all elements of a * B is______ .
3. Please introduce Einstein's famous equation E = MC2
4. How to read e = MC2 mass energy equation in English
5. How to deduce Einstein's mass energy equation? Is it reasonable to deduce e = HF = H / (C / in) = H / (C / (H / MV)) = MC2 according to Planck's photon energy formula? I think about it myself,
6. How did Einstein calculate the mass energy equation E = MC2?
7. What is the detailed derivation process of Einstein's mass energy equation?
8. Why is e = MC2 like this?
9. Explain that E = MC2 When we see Einstein's mass energy formula e = MC2, can we explain its derivation process and application in a more understandable language? How can we deduce that an object cannot move faster than the speed of light? M = M0 / root sign [1 - (V / C) ^ 2] (M0 is the static mass of the object, V is the moving speed of the object, C is the speed of light, M is the moving mass of the object) how do you get it?
10. How to understand the unit conversion in E = MC2?
11. Is set a I set a ∩ set B
12. What does set a / b mean I haven't done Math for a long time, a = [- 2,1] B = (0,2) What do you mean by a / b? Is it asking a to dig out B? AUB is the sum of two?? Anb is the overlap of two, right What's a / b???? I don't know what it means The problem is to find a / b
13. What does the MC symbol on the thermometer stand for
14. The meaning of MC element symbol It's a scientific element symbol. MC means that kind of element (for example, O is oxygen, etc.)
15. Narrate and prove the tangent length theorem
16. How to express the tangent length theorem
17. Tangent length theorem 1. In the trapezoid ABCD, ad ‖ BC, ∠ ABC = 90 ° the semicircle o with ab as diameter cuts CD at point M. if the trapezoid has an area of 10 square centimeters and a perimeter of 14cm, what is the radius of semicircle o? 2. The side length of square ABCD is a, AE cuts the semicircle with diameter BC to e, intersects DC to F, and finds CF: FD
18. What is the tangent length theorem?
19. Tangent length theorem
20. Two identical spherical conductors, suspended at the same point by thin insulated wires of 13 cm in length, have the same amount of charge (can be regarded as point charge). Due to electrostatic repulsion, the distance between them is 10 cm. The mass of each spherical conductor has been measured to be 0.6 g, and the amount of charge they carry is calculated. (known electrostatic constant k = 9 × 109 n · m2 / C2)