1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
aliina [53]
3 years ago
9

Show that in a group of five people (where any two people are either friends or enemies), there are not necessarily three mutual

friends or three mutual enemies.
Mathematics
1 answer:
sveta [45]3 years ago
8 0

Answer:

Lets call the people A,B,C,D and E. We need to find an example where there are not 3 mutual friends and not three mutual enemies.

Lets start by assuming that A has 2 friends, B and C, and 2 enemies, D and E.

Since we want A,B and C not to be mutually friends, then B and C neccesarily have to be enemies.

Now, since B and C are enemies, they cant be enemies at the same time with D, and they also cant be enemies at the same time with E. Therefore one of them has to be friends with D and one has to be friends with E.

Also, since D and E are enemies with A, they neccesarily need to be friends.

From the fact that D and E are friends, we coclude that they cant have a friend in common, as a consequence, B has to be friends with one of D and E and C has to be friend with the other. We can assume that B is friend with D and C is friend with E. If we use that, we have the following friendship configuration

---------------------

Friends of A: B, C

Enemies of A: D,E

-------------------------

Friends of B: A,D

Enemies of B: C, E

------------------------

Friends of C: A,E

Enemies of C: B,D

------------------------

Friends of D: B,E

Enemies of D: A,C

----------------------------

Friends of E: C,D

Enemies of E:  A,B

--------------------------

As you can check, there is not three mutual friends nor three mutual enemies.

You might be interested in
A quilt is made of 12 squares of equal size. Each square measures 15 cm by 15 cm.
kolezko [41]

Answer:    12    x    15= 180 cuadrados

juas juas juas 180  +   180  = 360


15 x 15 cm = 360

Step-by-step explanation:

3 0
2 years ago
Read 2 more answers
Which arc is a minor arc?
egoroff_w [7]

Answer: The answer you selected PS is correct.

Step-by-step explanation: A minor arc is a arc that is less than or equal to 180 degrees. PS looks to be exactly 180 degrees or at least close to it.

3 0
3 years ago
Read 2 more answers
Carrie has a stamp collection she is very proud of. She buys a frame to display her favorite stamps. The frame is 6 inches wide,
olga55 [171]
The stamps should be .85 inches each
7 0
3 years ago
A recipe calls for 15 oz of flour every 8 oz of milk. If you use 16 oz of milk, how much flour will you use?
fgiga [73]

Answer:30 oz of flour

Step-by-step explanation:

Hope it helps

5 0
3 years ago
Write "five more than a number" as a math expression help please
sp2606 [1]

Answer:

It is 5 or  x>5

Step-by-step explanation:

8 0
2 years ago
Other questions:
  • An integer for 9 steps forward
    15·1 answer
  • Malik buys and sells car parts. He bought two tires for $45.00 each and later sold them for $65.00 each. He bought three rims fo
    8·1 answer
  • Sam tutors math. For each hour that he tutors, he earns 20
    12·2 answers
  • Hayley is considering two gym membership plans. The plans are detailed here.
    7·1 answer
  • How many (15in by 15in by 25in) boxes will fill a container (10ft by 15ft by 50ft) box provided 135cubit ft. of space is
    10·1 answer
  • What is 80 x 35%=???????????????????????????
    9·1 answer
  • If 0 < b ≤ 90 and cos(11b + 2) = sin(12b − 4), what is the value of b?
    8·2 answers
  • There are 20 pieces of bread to divide among 20 people. A man eats 3 pieces, woman eats 2 pieces and a child eats half piece of
    13·1 answer
  • Pls help (see picture)
    5·2 answers
  • While attending a film festival you decide that there are 13 movies that you are interested in seeing. However, you only have ti
    14·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!