At a friend's party, everyone shakes hands 28 times. If everyone at the party shakes hands with everyone else only once, how many people are there?

At a friend's party, everyone shakes hands 28 times. If everyone at the party shakes hands with everyone else only once, how many people are there?

Suppose there are x people at the party, and each of them should shake hands (x-1) times. The equation is x (x-1) = 28 × 2, and the solution is X1 = 8, X2 = - 7. A: there are 8 people at the party

Someone has the flu. After two rounds of infection, 64 people have the flu
There is one person suffering from influenza, and after two rounds of infection, there are 64 people suffering from influenza. (1) how many people are infected by one person in each round? (2) if there is no one person suffering from influenza, there are 64 people suffering from influenza after two rounds of infection. (1) how many people are infected by one person in each round? (2) if it is not controlled in time, how many people will be infected in the third round?
(seek specific process)

Let one infect X in each round, then
1+x+（1+x）x=64
The solution is x = 7, x = - 9
After three rounds of transmission, the number of influenza patients = 64 × 7 = 448
So the answer is: 7448
Suppose that one person infects x people in each round of infection, then x people will be infected after the first round of infection, and then x (x + 1) + X + 1 people will be infected after two rounds of infection. It is known that 64 people will be infected after two rounds of infection. The equation is solved by the equivalent relationship of the number of people infected after two rounds of infection

A computer virus spreads very fast. If a computer is infected, after two rounds of infection, m computers will be infected,
If in each round of infection, an average computer will infect n computers, find the functional relationship between M and n

On average, one computer will infect x computers in each round of infection
After the first round, 1 + X stations were infected
After the second round, 1 + X + X * (x + 1) = (x + 1) ^ 2 units were infected
So there are:
（x+1）^2=81
The solution is: x = 8 or x = - 10 (rounding off)
After the third round:
81+81*8=81*9=729>700

Every two people who attended a party shook hands once, and all of them shook hands 10 times______ People go to the party

According to the equation, X (x-1) 2 = 10, the solution is X1 = 5, X2 = - 4. A: there are 5 people attending the party. So the answer is: 5

Every two people who attend a party shake hands once. All of them shake hands 66 times. How many people attend the party? Set () equation as ()

A total of X participants participated
x(x-1)/2 =66
x(x-1)=132
x²-x-132=0
(x-12)(x+11）=0
X1 = 12, X2 = - 11
A: there were 12 people at the party
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Every two people who attend a party shake hands once. All the people shake hands 10 times. How many people attend the party? (just list the quadratic equation with one variable)

Suppose there are x people in all
x*(x-1)/2=10
x^2-x-20=0
(x-5)(x+4)=0
x+4>0
x-5=0
x=5
There are five people in all

Every two people at a party shook hands once. Everyone shook hands 21 times. How many people attended the party

7 people

Every two people who attended a party shook hands once, and all of them shook hands 10 times______ People go to the party

According to the equation, X (x-1) 2 = 10, the solution is X1 = 5, X2 = - 4. A: there are 5 people attending the party. So the answer is: 5

In a classmate party, every two people shake hands once, and all people shake hands 10 times. If x people attend the party, the equation is as follows:
What's the final answer?

Because everyone wants others to shake hands once, so everyone shakes hands X-1 times,
A total of X people, shake hands x (x-1) times, repeat once, so need to divide by 2
The equation is x (x-1) / 2 = 10

Every two people who attended a party shook hands once, and all of them shook hands 10 times______ People go to the party

According to the equation, X (x-1) 2 = 10, the solution is X1 = 5, X2 = - 4. A: there are 5 people attending the party. So the answer is: 5