Discrete math - proof of divisibility question

In summary, discrete math is a branch of mathematics that deals with objects that can only take on distinct, separated values. It involves the study of mathematical structures and relationships between discrete objects. A proof of divisibility is a mathematical argument that shows a given number is divisible by another number without leaving a remainder. In discrete math, divisibility is determined by using the division algorithm, which states that if a number a is divided by a non-zero number b, the result is a quotient q and a remainder r. If the remainder is 0, then a is divisible by b. Some common methods used to prove divisibility in discrete math include mathematical induction, direct proof, proof by contradiction, and proof by contrapositive. These methods use logical
  • #1
dgamma3
12
0
is this true or false:

If a|b and a|c, then one (or both) of b|c or c|b holds.

if I want to disprove this, can I:

let a = 5, x = 2 and y = 3.

b=ax
c=ay

then c=bz
and c = bg doesn't hold.
 
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  • #2
Why make it so complicated? You constructed a counter-example:

a=5 , b=10 c=15 , and neither 10|15 nor 15|10.
 

Related to Discrete math - proof of divisibility question

1. What is discrete math?

Discrete math is a branch of mathematics that deals with objects that can only take on distinct, separated values. It involves the study of mathematical structures and relationships between discrete objects.

2. What is a proof of divisibility?

A proof of divisibility is a mathematical argument that shows a given number is divisible by another number without leaving a remainder. It involves using mathematical concepts and logical reasoning to demonstrate the divisibility relationship between two numbers.

3. How is divisibility determined in discrete math?

In discrete math, divisibility is determined by using the division algorithm, which states that if a number a is divided by a non-zero number b, the result is a quotient q and a remainder r. If the remainder is 0, then a is divisible by b.

4. What are some common methods used to prove divisibility in discrete math?

Some common methods used to prove divisibility in discrete math include mathematical induction, direct proof, proof by contradiction, and proof by contrapositive. These methods use logical reasoning and mathematical concepts to show that a given number is divisible by another number.

5. How is discrete math used in real-world applications?

Discrete math has many real-world applications, including computer science, cryptography, coding theory, and operations research. It is used to solve problems related to discrete structures, such as graphs, networks, and algorithms, which have practical applications in various fields.

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