If both sides of an equation are undefined does that mean its true?

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In summary, the conversation discusses the results of a test question with two possible choices. The individual initially chose B but questions whether or not it was the correct answer due to the concept of infinity and undefined values. It is concluded that neither choice was correct as the statements are not properly connected and the concept of infinity cannot be equated to a specific number.
  • #1
breebreebran
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I was taking a test and basically for the answer I had limited it to two choices.
A: x=3 and x does not equal 2
or
B. x=3 x=2

When I plug in three, I got 3/1=12/4 so three is true.
But when I plugged in two I got 3/0=8/0
So would this be true too? Or does x not equal 2?
Wouldnt undefined on both sides be the same as infinity=infinity making it true?
I already turned my test in and I chose B. Was I right?
 
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  • #2
"Wouldnt undefined on both sides be the same as infinity=infinity making it true?"
Totally wrong. Undefinedness, or infinity for that matter, is not a number, and hence, cannot "Equal" anything, since "equality" is a relation between numbers.

"I already turned my test in and I chose B. Was I right?"
No.
 
  • #3
breebreebran said:
I was taking a test and basically for the answer I had limited it to two choices.
A: x=3 and x does not equal 2
or
B. x=3 x=2
Statement A is true if x is equal to 3, and false for all other values of x. If x = 3, the first part is obviously true, as is the second part, since x is not equal to 2.

Statement B - I can't tell, since there is no connector between the two statements. If the missing connector is "and", then the statement is false, since x can't simultaneously be 2 and 3. If the connector is "or", then statement B is true if the value of x is either 2 or 3. It would be false for any other values of x
breebreebran said:
When I plug in three, I got 3/1=12/4 so three is true.
No, 3 is neither true no false - it's a value. Only statements (such as equations or inequalities) can be true or false.
breebreebran said:
But when I plugged in two I got 3/0=8/0
So would this be true too? Or does x not equal 2?
Wouldnt undefined on both sides be the same as infinity=infinity making it true?
I already turned my test in and I chose B. Was I right?
No
 
  • #4
breebreebran said:
I was taking a test and basically for the answer I had limited it to two choices.
A: x=3 and x does not equal 2
or
B. x=3 x=2

When I plug in three, I got 3/1=12/4 so three is true.
But when I plugged in two I got 3/0=8/0
So would this be true too? Or does x not equal 2?
Wouldnt undefined on both sides be the same as infinity=infinity making it true?
I already turned my test in and I chose B. Was I right?

It would help if you displayed the equation you are talking about.
 
  • #5
Even if infinity exists within a number set, it still can't be counted on to equal itself. Infinity is more like a class of numbers then anyone specific number. An infinite value might be countable, or uncountable, for example, and those would never equal to each other.
 

Related to If both sides of an equation are undefined does that mean its true?

1. What does it mean if both sides of an equation are undefined?

Undefined means that there is no value or solution for that particular variable in the equation. It could also mean that the equation is not valid or does not follow the rules of mathematical operations.

2. Does an undefined equation always mean that it is true?

No, an undefined equation does not always mean that it is true. It could simply mean that the equation is not valid or does not have a solution. It is important to check the validity of the equation before assuming it is true.

3. Can an equation be both undefined and true?

No, an equation cannot be both undefined and true. If an equation is undefined, it means that it does not have a solution and therefore cannot be true. However, an equation can be undefined and valid if it follows the rules of mathematical operations.

4. How do I know if an equation is undefined?

If an equation contains variables that cannot be solved or has operations that do not follow the rules of mathematics (such as dividing by zero), then it is considered undefined. It is important to check each variable and operation in the equation to determine if it is valid or not.

5. Is it possible for an equation to have an undefined side and a defined side?

Yes, it is possible for an equation to have an undefined side and a defined side. This could happen if one side of the equation has a variable that cannot be solved, while the other side has a defined value or solution. In this case, the equation would be considered undefined overall.

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