If the relative acceleration between objects is zero, there must be static friction between two objects

If the relative acceleration between objects is zero, there must be static friction between two objects

For example, you are holding two stacked books and accelerating upward. The relative acceleration of the two books is zero, but there is no static friction between them

Xiao Hong read a historical story book. It has 51 Pages in total. She has read 27 pages. How many parts of the book have she read? How many parts of the book are the remaining pages?
Better be before 9 o'clock today!

27 divided by 51 = 9 / 19
2.1-9 / 19 = 10 / 19

The sum of two even numbers is 178. What are the two numbers

x+x+2=178
2x=178-2
x=88
88+2=100
The two numbers are 88 and 100 respectively
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The nth root of zero is zero. Right?

No, it can't be a negative power of 0

7 * 9 = 63 11 * 13 = 143 79 * 81 = 6399 8 * 8 = 64 12 * 12 = 144 80 * 80 = 6400. What is the rule from these formulas?

7 * 9 = 63 11 * 13 = 143 79 * 81 = 6399 these three square difference formulas: (a-b) (a + b) = a ^ 2 - B ^ 2 for example: 79 * 81 = (80-1) * (80 + 1) = 80 ^ 2 - 1 ^ 2 = 6400-1 = 6399 8 * 8 = 64 12 * 12 = 144 80 * 80 = 6400 these three complete squares 79 * 81 are one less than 80 * 80, that is (n-1) (n + 1) =

Given that the solution of the system of equations 3kx + 2Y = 6k2x + y = 8 satisfies the equation x + y = 10, find K

∵ x + y = 10 (1), 2x + y = 8 (2), from (1) - 2 we get x = - 2, y = 12, substituting the values of X and Y into 3kx + 2Y = 6K, we get: - 6K + 24 = 6K, we get k = 2

If f (- 1) = 0, then the solution set of inequality f (x) > 0

Because it is an even function, f (- x) = f (x)
That is, f (- 1) = f (1) = 0
Because f (x) is a decreasing function at (- ∞, 0), when X0
When x > 1, f (x) > 0
The solution set of F (x) > 0 is (- ∞, - 1) U (1, + ∞)

The distance between a and B is 3.6 kilometers. The two dogs run from a and B to each other. They run 450 meters and 350 meters per minute respectively. After running for one minute, they turn back and run for two minutes, turn back and run for three minutes, and then turn back and run for four minutes In this way, until the meeting, from the start to meet the need______ Minutes

According to the meaning of the question: every minute they ran: 450 + 350 = 800 (meters). We may as well list as follows: the first phase (1 minute): 3600-800 = 2800 (meters); the first reverse (2 minutes): 3600-800 + 800 × 2 = 4400 (meters); the second phase (3 minutes): 3

123-45-67 + 89 = 100 add three matchsticks at will or equal to 100
See how to get 100

123-4-5-6-7+8-9=100

It is urgent to solve 20 problems of linear equations with one variable,

1.2(x-2)-3(4x-1)=9(1-x)
2x-4-12x+3=9-9x
x=-10
2.11x+64-2x=100-9x
18x=36
x=2
3.15-(8-5x)=7x+(4-3x)
15-8+5x=7x+4-3x
x=-3
4.3(x-7)-2[9-4(2-x)]=22
3x-21-2(9-8+4x)=22
3x-21-2-8x=22
-5x=55
x=-11
5.2(x-2)+2=x+1
2x-4+2=x+1
x=3
6.30x-10(10-x)=100
30x-100+10x=100
40x=200
x=50
7.4(x+2)=5(x-2)
4x+8=5x-10
x=18
8.120-4(x+5)=28
120-4x-20=28
-4x=-72
x=18
9.15x+854-65x=54
-50x=-800
x=16
10.3(x-2)+1=x-(2x-1)
3x-6+1=x-2x+1
4x=6
x=3/2
11.11x+64-2x=100-9x
18x=36
x=2
12.14.59+x-25.31=0
x=10.72
13.(x-6)×7=2x -2
7x-42=2x-2
5x=40
x=8
14.3x+x=18
4x=18
x=9/2
15.12.5-3x=6.5
3x=6
x=2
16.1.2(x-0.6)=4.8
1.2x- 7.2=4.8
1.2x=12
x=10
17.x+12.5=3.5x
2.5x=12.5
x=5
18.8x-22.8=1.2
8x=21.6
x=2.7
19.2x=5x-3
3x=3
x=1
20.x+5=8
X = 3. It's once a dollar
1) 66x+17y=3967
25x+y=1200
Answer: x = 48, y = 47
(2) 18x+23y=2303
74x-y=1998
Answer: x = 27, y = 79
(3) 44x+90y=7796
44x+y=3476
Answer: x = 79, y = 48
(4) 76x-66y=4082
30x-y=2940
Answer: x = 98, y = 51
(5) 67x+54y=8546
71x-y=5680
Answer: x = 80, y = 59
(6) 42x-95y=-1410
21x-y=1575
Answer: x = 75, y = 48
(7) 47x-40y=853
34x-y=2006
Answer: x = 59, y = 48
(8) 19x-32y=-1786
75x+y=4950
Answer: x = 66, y = 95
(9) 97x+24y=7202
58x-y=2900
Answer: x = 50, y = 98
(10) 42x+85y=6362
63x-y=1638
Answer: x = 26, y = 62
(11) 85x-92y=-2518
27x-y=486
Answer: x = 18, y = 44
(12) 79x+40y=2419
56x-y=1176
Answer: x = 21, y = 19
(13) 80x-87y=2156
22x-y=880
Answer: x = 40, y = 12
(14) 32x+62y=5134
57x+y=2850
Answer: x = 50, y = 57
(15) 83x-49y=82
59x+y=2183
Answer: x = 37, y = 61
(16) 91x+70y=5845
95x-y=4275
Answer: x = 45, y = 25
(17) 29x+44y=5281
88x-y=3608
Answer: x = 41, y = 93
(18) 25x-95y=-4355
40x-y=2000
Answer: x = 50, y = 59
(19) 54x+68y=3284
78x+y=1404
Answer: x = 18, y = 34
(20) 70x+13y=3520
52x+y=2132
Answer: x = 41, y = 50
Binary linear equations for building owners to choose