Induction for writing integers

In summary, this problem asks for a proof that every natural number is a product of two positive integers. The first step is to show that every odd number is a product of two positive integers. The second step is to show that every even number is a product of two positive integers. However, this proof does not provide a proof that every number is a product of two positive integers.
  • #1
KOO
19
0
Prove that every n E N can be written as a product of odd integer and a non-negative integer power of 2.

For instance: 36 = 22 * 9
 
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  • #2
KOO said:
Prove that every n E N can be written as a product of odd integer and a non-negative integer power of 2.

For instance: 36 = 22 * 9

If n is odd, we can write it as [tex]\displaystyle \begin{align*} n = n \cdot 2^0 \end{align*}[/tex].

If n is even (including 0), it must have a factor of 2, so we can write it as [tex]\displaystyle \begin{align*} n = 2^1 k \end{align*}[/tex].

Q.E.D.
 
  • #3
Prove It said:
If n is odd, we can write it as [tex]\displaystyle \begin{align*} n = n \cdot 2^0 \end{align*}[/tex].

If n is even (including 0), it must have a factor of 2, so we can write it as [tex]\displaystyle \begin{align*} n = 2^1 k \end{align*}[/tex].
This is not enough to prove the required claim.
 
  • #4
KOO said:
Prove that every n E N can be written as a product of odd integer and a non-negative integer power of 2.

For instance: 36 = 22 * 9
What about powers of 2? 2^k (k being a positive integer) has no odd factors, unless you want to include 1.

-Dan
 
  • #5
topsquark said:
What about powers of 2? 2^k (k being a positive integer) has no odd factors, unless you want to include 1.
Well, we want to include 1. Thus, if $k$ is a nonnegative integer, then $2^k=1\cdot2^k$: here 1 is an odd integer and $2^k$ is a non-negative integer power of 2, so this factorization satisfies the problem statement.

Obviously, a proof of this fact uses repeated division by 2. It can be made precise using strong induction.

There was https://driven2services.com/staging/mh/index.php?posts/33828/ here about MathStackExchange (MSE), and the format that encourages dialogue was mentioned as a feature that distinguishes this forum from MSE. So I suggest that the OP write his/her reaction to what has been said so far and also the topic that this problem is supposed to teach (such as strong induction, direct proofs, or divisibility).
 

Related to Induction for writing integers

1. What is induction for writing integers?

Induction for writing integers is a mathematical method used to prove that a statement is true for all positive integers. It involves three steps: base case, inductive hypothesis, and inductive step.

2. How does induction for writing integers work?

Induction for writing integers works by starting with a base case, which is usually the smallest positive integer that the statement is true for. Then, the inductive hypothesis assumes that the statement is true for a particular integer, and the inductive step proves that it is also true for the next integer. This process is repeated until it can be shown that the statement is true for all positive integers.

3. What are the benefits of using induction for writing integers?

The benefits of using induction for writing integers include the ability to prove statements for all positive integers without having to check each individual case. It also provides a structured and logical approach to proving mathematical statements.

4. Can induction be used for other types of numbers besides integers?

Yes, induction can be used for other types of numbers such as real numbers and complex numbers. However, the process may be more complex and may require different methods.

5. Are there any limitations to using induction for writing integers?

One limitation of using induction for writing integers is that it can only be used to prove statements for positive integers. It cannot be used for negative integers or non-integer numbers. Additionally, it may not be applicable or efficient for certain types of mathematical statements.

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