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Five students sign up for three projects. They are required to apply for all three projects. How many kinds of application methods are there?
1 2 or 1 1 3
But the calculation is wrong
3 * 5 * C42 (4 in the bottom, 2 in the top, do you understand this?) + 3 * C53 * 2 = 150
A permutation problem in Senior Two
Line up two boys and four girls
1. How many ways do boys rank in the middle?
2. How many kinds of arrangement are there when boys are not at the head and tail?
3. How many kinds of non adjacent arrangements are there for boys?
4. How many kinds of arrangements are there for boys who are not adjacent and not at the head and tail?
5. How many arrangements are there for two boys who are not adjacent to girl a?
I've been thinking all night. I almost want to die. It's ambiguous. Let's talk about it
Besides, I don't choose the best one who answers first.
1.24
two point two one six
three point four eight zero
four point one four four
5. Trouble, I haven't thought about it for the time being
I'm in a hurry
Baidu Hi and you said, the first question and the second question are certainly not the same, not in the beginning and end does not mean in the middle
Permutations and combinations in Senior Two
There are six male doctors and four female doctors
If 10 doctors are divided into two groups, 5 in each group, and each group has female doctors, how many different methods are there? If the two groups of doctors are assigned to two places, and two chief and deputy leaders are selected, how many methods are there?
(1) When there was one female doctor in a group, there were (4 * 1 / 1) * (6 * 5 * 4 * 3 / 4 * 3 * 2 * 1) = 60 methods, and when there were two female doctors on one side, there were (4 * 3 / 2) * (6 * 5 * 4 / 3 * 2 * 1) = 120 methods, a total of 180 methods
(2) A total of 180 × 2 = 360 species were distributed in the two places, and 5 × 4 = 20 species were selected in the first group, with a total of 360 × 20 = 7200 species
At present, there are four teachers participating in the lesson presentation competition, and there are four alternative topics. If each player randomly selects one topic from among them for lesson presentation, there is just one topic that has not been selected by these four teachers ()
A. 288 species B. 144 species C. 72 species D. 36 species
According to the meaning of the questions, each teacher has four choices, so the four teachers have 44 choices without omission, among which C24 (c34a22 + C24) = 84 is exactly two questions not selected, 4 are exactly three questions not selected (four people choose the same question, there are 4 kinds), and 0 is exactly one question not selected (all four questions are selected, a44 = 24). So there are 256-84-4-24 = 144
Use 0,1,2,3,4 to form five digits without repetition
(1) If odd numbers are adjacent and even numbers are adjacent, how many five digit numbers are there
(2) If the absolute value of the difference between a ten thousand digit number and a one digit number is 2, how many five digit numbers are there?
(1) When 13 is in the front and 240 is in the back, there is no limit. The number of permutations is: P (2,2) * P (3,3) = 2 * 6 = 12. When 240 is in the front and 13 is in the back, 0 cannot be placed first, so the number of permutations is: (2 * 2 * 1) * P (2,2) = 8. So there are n = 12 + 8 = 20 kinds (2). When the first one is 2, the last one is 0, P (3,3) = 6
Let the number of machines be 8 bits. Given y = - 011010, please write the original code, complement code and inverse code of Y respectively
True value: - 011010
Original code: 10110110
Inverse code: 11001001
Complement: 11001010
First of all, the original code, complement code and inverse code of the sign of truth value are all the same: the highest bit (we call sign bit) is 0 for positive and 1 for negative
The source code, complement code and inverse code of positive numbers are the same
Negative numbers are special. The following introduces the transformation of the original code, complement code and inverse code of negative numbers:
Through the original code inversion method: the sign bit unchanged, the rest of you were negative
The method to find the complement by the original code: first find the inverse of the original code, and then add 1 to the inverse. (note that the complement operation of the machine will overflow the highest bit!)
Find the original code through the complement: subtract 1 from the complement, the sign bit of the result remains unchanged, and the other bits are negated
The word length of the machine is 8 bits, and the original code, inverse code and complement code of decimal number - 28 can be obtained
11100010
ten million eleven thousand one hundred and one
ten million eleven thousand one hundred and ten
The length of machine number is 8 bits. If the machine number is 81h, when it represents the original code, complement code, inverse code and shift code, what are the equivalent decimal systems?
Algorithm, all kinds of codes have formulas. Complement formula: machine number = 256 + true value (when machine number is greater than 127), then: true value = machine number - 256 = 129 - 256 = - 127.
Suppose that the number of machines in a computer is 8 bits, try to write the original code, inverse code and complement of decimal number - 67
Specific description and process
The original code of 67 is 01000011 (the first bit is the sign bit, "0" represents a positive number, and "1" represents a negative number)
-The original code of 67 is 11000011, because the original code, inverse code and complement code of positive numbers are the same, while the inverse code of negative numbers = the inverse of each bit of the original code (that is, 0 changes to 1, 1 changes to 0, and the sign bit cannot change)
Complement of negative number = inverse of negative number + 00000001,
So the original code of - 67 is 11000011, the inverse code is 10111100, and the complement code is 10111101
Computer original code complement
If the 8-bit complement is 10110110, then the 16 bit complement is 111111011010. If the 8-bit complement is 01011001, then the 16 bit complement is 000000000 101101. If the 8-bit complement is 10110110110, then the 16 bit complement is 10110110110. If the 8-bit complement is 01011001, then the 8-bit complement is 10110110. If the 8-bit complement is 10110110, then the 16 bit complement is 10110110. If the 8-bit complement is 10110110, then the 16 bit complement is 10110110. If the 8-bit complement is 01011001, then the 16 bit complement is 10110. Why the first one is always?
The highest bit of the complement, which can represent positive and negative numbers
It is also called sign bit
When expanding the number of bits, the sign does not change
So, if it turns out to be 1, add a string of 1. If it turns out to be 0, add a string of 0
RELATED INFORMATIONS
- 1. About computer source code, inverse code and complement code The complement of a negative number is its original code. In addition to the sign bit, it "negates each bit" and adds 1 to the lowest bit. For example, the complement of - 79 is 10110001, and the complement of - 80 is 10110010?
- 2. What is the difference between logical right shift and arithmetic right shift?
- 3. A spring dynamometer, two people pull its two ends with horizontal tension, at this time the reading of the spring dynamometer is 20n, then the force of the two people is () A. Two people use 10N force B. two people use 20n force C. one person uses 20n force, the other person does not use force D. one person uses 5N force, the other person uses 15N force
- 4. It is known that the mechanical efficiency of machine a is 65%, and that of machine B is 80% A. Machine a must save labor than machine B. machine a must save distance than machine B. machine a must do more useful work than machine B. all the above statements are wrong
- 5. Principles of Computer Organization (Second Edition) Tang shuofei Page 73 main memory has an address allocation for a storage unit in main memory. It gives an example: for 24 bit address line Is this example wrong? Yes, explain it to me
- 6. Why can complement realize symbol bit operation? For example, I want to know an easy to understand explanation, especially the complement of negative numbers Your answer is also the conclusion that I have come to during this period of study. Indeed, it is better to understand the meaning of the complement given to the number by directly corresponding the complement with the number
- 7. With the help of calculator or computer, the real number solution (accurate to 0.01) of the spherical equation 2 ^ X - X & sup2; = 0 in the interval (- 1,0) is solved by dichotomy
- 8. Use the computer to find the approximate value of the following number, and keep the following three digits. Because there is no computer, please (1) negative root sign 5 (2) positive and negative root sign 6.21 (3) root sign 1 and 1 / 6
- 9. Xiao Fang designed a calculation program with computer. The input and output data are as follows: input 1 2 3 4 5 … Output So, when Enter 1 2 3 4 5 … Output 1 in 2, 4 in 17, 5 in 26 What is the output data when input 8?
- 10. BV-0.75 2x2.5 PC20 WC/CC A good man is safe all his life!
- 11. Several easy permutation and combination questions 1. How many numbers can be made up of 0 1 2 3 (1) Three figures (2) Three digits without repetition (3) Three odd numbers (4) Three digits of a multiple of 5 (5) Numbers that do not repeat and are greater than 130 2.6 people in a row, the following conditions are several arrangements (1) A can't stand in line (2) A can't stand at the head or the tail of the line (3) Party A and Party B are adjacent to each other (4) Party A and Party B cannot be adjacent (5) There are three people in the front and three in the back of the two lines, and Party A and Party B are not in the same line.
- 12. Ask for explanation Given six numbers 0 1 2 3 5 9, how many natural numbers can be formed without repetition?
- 13. Arrangement and combination of the problem, the mathematical Emperor help 1. There are ten identical books and three different boxes. At least one book is put in each box. How many ways are there?
- 14. Using database management information, people must first turn the specific characteristics of things into data that can be processed by computer through human brain
- 15. M + on the computer
- 16. In order to promote sales, a shopping mall reduced the price of a commodity by 18%. Later, it was found that it lost money to sell at this price, so it increased by 8%. After two price adjustments, the price was 177.12 yuan, How much is the original price?
- 17. How to use the M + m-mrc in the lower left corner of the calculator?
- 18. Discriminant of the root of quadratic equation with one variable We know the equation x & # 178; + (M + 2) x + 2m-1 = 0 (1) Proof: the equation has two unequal real roots (2) When m is the value, the two parts of the equation are opposite to each other, and the solution of the equation is obtained
- 19. It is known that X1 and X2 are two real roots of the quadratic equation 4kx ^ 2-4kx + 1 = 0. 1 It is known that X1 and X2 are two real number roots of the quadratic equation 4kx ^ 2-4kx + 1 = 0. 1. Is there a real number k such that (2x1-x2) (x1-2x2) = - 3 / 2? If so, find the value of K. if not, explain the reason. 2. Find the integer value of the real number k with the value of X1 / x2 + x2 / x1-2 as an integer
- 20. Equation: 3x + 4Y-2 + λ (2x + y + 2) = 0 represents the intersection of the line 3x + 4Y-2 = 0 and the line 2x + y + 2 = 0 Why does it mean the intersection point,