Prove that the square of any integer, when divided by 3. only by odd and even.

In summary: The possibilities that need to be considered for the integer are 3m, 3m+1, or 3m+2, where m is any integer. This covers all possible cases for the integer when divided by 3.
  • #1
dgamma3
12
0

Homework Statement



I know you could prove this by stating every integer is either 3m, 3m+1 or 3m+2. However I am trying to prove this just using either even numbers or odd numbers.

so for example, when I try:
(2x+1)^2
= 4x^2 + 4x + 1 - expand
= 3x^2 + x^2 + 3x + x + 1 - group like terms
= 3x^2 + 3x + x^2 + x + 1
= 3*(x^2 + x) + x(x+1) + 1

x(x+1) + 1 is an odd number

so
= 3*(x^2 + x) + 2p + 1

thats as far as I can go.

thanks
 
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  • #2
dgamma3 said:

Homework Statement



I know you could prove this by stating every integer is either 3m, 3m+1 or 3m+2. However I am trying to prove this just using either even numbers or odd numbers.

so for example, when I try:
(2x+1)^2
= 4x^2 + 4x + 1 - expand
= 3x^2 + x^2 + 3x + x + 1 - group like terms
= 3x^2 + 3x + x^2 + x + 1
= 3*(x^2 + x) + x(x+1) + 1

x(x+1) + 1 is an odd number

so
= 3*(x^2 + x) + 2p + 1

thats as far as I can go.
What are you trying to prove?
Your thread title seems to be missing a few words
Prove that the square of any integer, when divided by 3. only by odd and even.
Prove that the square of any integer, when divided by 3, does what?

The problem template has a problem statement section titled, and this is where the statement of the problem should go. Use it.
 
  • #3
sorry mate.

Prove that the square of any integer, when divided by 3, leaves remainder 0 or 1 but never 2.
thanks
 
  • #4
What possibilities do you need to consider for the integer?
 

What is the statement being proven?

The statement being proven is that the square of any integer, when divided by 3, will result in either an odd or even number.

What is the significance of this statement?

This statement is significant because it provides a rule or pattern for determining whether a number is odd or even, without having to perform the actual division calculation.

How can this statement be proven?

This statement can be proven using the properties of even and odd numbers, as well as the properties of division.

What are the steps to prove this statement?

The steps to prove this statement are as follows: 1) Begin with an arbitrary integer, n. 2) Square n to get n^2. 3) Divide n^2 by 3. 4) Use the properties of even and odd numbers to show that the resulting number is either even or odd. 5) Since n was arbitrary, this pattern applies to all integers.

Why is it important to use the properties of even and odd numbers in the proof?

Using the properties of even and odd numbers in the proof helps to show that the resulting number after division by 3 will always be either even or odd, regardless of the original integer used. This strengthens the validity of the statement being proven.

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