Summary of knowledge points in Chapter 7-9 of physics in Volume 2 of Grade 8

Chapter 7 force 1, force 1, the concept of force: force is the action of an object on an object. 2, the unit of force: Newton, abbreviated as cow, expressed in N. perceptual knowledge of force: the force used to take two eggs is about 1n. 3, the effect of force: force can

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1. There is a pile of colored beads, arranged by three red and two green. What's the color of the 28th bead? What's the color of the 49th bead?
2. I record how many shots each person hits. What's everyone's percentage of hits?
3. The product of two prime numbers less than 1000 is an even number, which is most likely to be
4. ABCD represents four different natural numbers, and a * b * c * d = 2709, then what is the maximum and minimum of a + B + C + D?
5. It is known that a, B, C, D are natural numbers, and a × B = 24, C × d = 32, B × d = 48, B × C = 24, ask a = 1___ ，B= ___ ，C= ___ ，D= ___ ．
6. a. B, C, D are four different natural numbers, and a * b * c * d = 1995, what is the minimum value of a + B + C + D?
7. There is a problem: ABCD four natural numbers, followed by less than 16, known a is 3 times D, find the value of ABCD, how to do ah Such as the title
8. (A / 1 + B / 1 + C / 1 + D / 1) + 36 / 1 + 45 / 1 = 1 a B C D is four continuous natural numbers a + B + C + D =? Urgent need
9. There are four natural numbers a, B, C and D. the least common multiple of a and D is 36, and the least common multiple of C and D is 90 a. What is the least common multiple of B, C and D? The least common multiple of a and B is 36,
10. If we know (1 + A + 1 / B + 1 / C + 1 / D) + 1 / 36 + 1 / 45 = 1, and a, B, C and D are just four continuous natural numbers, we can find the sum of a, B, C and D Today is the day,
11. New people's consultation series 3 8 17 32 57 () 3 8 17 32 57 () 3 + 8 + 6 8 + 17 + 7 17 + 32 + 8 32 + 57 + 9 = 98 is that right What's wrong with 3 + 8 + 68 + 17 + 717 + 32 + 832 + 57 + 9 = 98
12. On the simplification of mathematical integral in Grade Seven~~~~ I want 20 simplified calculation problems of integral in seventh grade mathematics, that is to say: the square of a + {A-D + [A-D]} - B, similar problems had better have square or cube, remember! Do not use the problem ~ ~ ~ and have the answer! I really get every point The world is really changing now. It's strange not to save money. Well, I'll just add more next time
13. Given AB = 2, find the value of a 2 − AB + 3B 2 a 2 + AB + 6B 2
14. What is the power of 4.2 × 10 to the 7th power △ 3 × 10 to the 5th power
15. Given A-B = 3, B-C = 5, find the value of AB AC BC, which is the second power of a + the second power of B + the second power of C
16. If we know that 1176 * a = B to the fourth power (AB is a non-zero natural number), then the minimum of a is ()?
17. It is known that ABC is a natural number, the power a of 2 is equal to 3, the power B is equal to 6, and the power C is equal to 6
18. Finding ab-cb = AC with power 2A = 3, power B = 6, power C (a, B, C are all natural numbers)
19. We know that the positive number a B C satisfies the power a of 2 is equal to the power B of 3 is equal to the power C of 6
20. As shown in the figure, in the triangle ABC, C = 2 b. prove: the square of ab - the square of AC = AC times BC The graph is an obtuse triangle