this post was submitted on 15 Oct 2024

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-49

A book costs $1 plus half it's price. How much does it cost? (sh.itjust.works)

submitted 3 weeks ago by [email protected] to c/[email protected]

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[–] [email protected] 26 points 3 weeks ago (1 children)

x = 1 + ½x → ½x = 1 → x = 2.

[+] [email protected] -15 points 3 weeks ago (2 children)

Can't have the same letter for the function and the variable, should be like this: y = 0.5(x) + 1

[–] [email protected] 13 points 3 weeks ago (1 children)

There is no function there, only an equation. And there is a single variable, "x", that represents the price of the book.

"x = 1 + ½x" is the same as "the price of the book is $1, plus half of the price of the book".

[–] [email protected] -3 points 3 weeks ago (1 children)

Ok, call it an equation or a function, it doesn't matter what it is called, the point was that the original comment is only true for the value that was used.

In the original comment we have "x = 1 + ½x" and the example used was with a cost of two (x=2) to show that the equation was true (ending in 2=2).

However if 4 is used instead (x=4) then we have ( 4 = 1 + ½[4] ) which results in an inequality (4=3) which is false.

Which is why I initially commented with a different letter on either side of the equal sign.

If you prefer to only put the value of x on the right side on the equal sign and not the left side, then a common notation for that is f(x) = 1 + ½x, which is also referred to as function notation.

https://en.m.wikipedia.org/wiki/Function_(mathematics)

[–] [email protected] 2 points 3 weeks ago (2 children)

Ok, call it an equation or a function, it doesn’t matter what it is called

What it is called does matter because a function obligatorily maps one set of values into another set of values, and that is not what I was doing because IDGAF about a full set dammit, but a single value that symbolises a price where OP's statement is true.

However if 4 is used instead (x=4) then we have ( 4 = 1 + ½[4] ) which results in an inequality (4=3) which is false.

As even 11yos know, but apparently not you, you don't solve an equation (or a set of equations) by arbitrarily assigning values to the variable.

If you prefer to only put the value of x on the right side on the equal sign and not the left side, then a common notation for that is f(x) = 1 + ½x, which is also referred to as function notation.

Congrats for not getting a value but a slope. 👍 /s

Juuuuuuuuuuuuust in case that your confusion is related to my usage of "→": it's clear by context that the symbol is being used for "implies".

[–] [email protected] 3 points 3 weeks ago (1 children)

This discussion is incredibly funny, because it is a discussion.
I personally prefer the equivalence (⇔) over the implication (⇒) since I like to emphasize that the statement is true in both directions. Well and having an incorrect base leads to funny statements on implications: x = x/2 ⇒ x = π is true.

[–] [email protected] 0 points 3 weeks ago

I'm glad that at least someone is getting some value out of it.

The equivalence symbol would be even better, indeed. But I can't type it with just AltGr+I, so I went for the simple arrow.

[–] [email protected] 0 points 3 weeks ago (1 children)

So after rereading the original post (which could have been written clearer) I think your equation in your original comment is written in a way that doesn't reflect the original post.

According to the original post the right side of the equal sign is cost plus half of the cost where cost is defined as $1. So then the equation would be x = 1+ ½(1) which solves to x = 1.5.

As even 11yos know, but apparently not you, you don't solve an equation (or a set of equations) by arbitrarily assigning values to the variable.

You are correct that assigning arbitrary values is not how to solve an equation (at least by hand), but I wasn't trying to solve the equation, I was showing that the equation as written would not be true unless 2 was used.

Juuuuuuuuuuuuust in case that your confusion is related to my usage of "→": it's clear by context that the symbol is being used for "implies".

Since the "→" notation is an alternative notation for a function, it made reading the math in your posts and the words in your posts contradictory. It would seem that you didn't read the Wikipedia link since the "→" notation is described there.

[–] [email protected] -1 points 3 weeks ago* (last edited 3 weeks ago)

So after rereading the original post (which could have been written clearer)

Okay... I'll stop reading here.

The original post is clear as day, even with the spelling mistake.

There's a certain level of lack of basic reasoning that I'm still willing to play along with; but this comment is past that. Not bothering further with you.

[–] [email protected] 6 points 3 weeks ago

It’s N equation and not a function…

[–] [email protected] 13 points 3 weeks ago

It costs nothing because you get it from LibGen.

[–] [email protected] 11 points 3 weeks ago (3 children)

The same question was posted yesterday. Are you a bot fishing for engagement?

[–] [email protected] 16 points 3 weeks ago

It's actually chatGPT and it just figured out outsourcing the questions to lemmy is more computationally efficient than burning through a few dozen video cards to derive the answer.

[–] [email protected] 5 points 3 weeks ago

Yes, Dave.

[–] [email protected] 1 points 3 weeks ago

This question was popular on Reddit few days ago.

[–] [email protected] 7 points 3 weeks ago

$1.50

[–] [email protected] 6 points 3 weeks ago

$3.50

[–] [email protected] 2 points 3 weeks ago

Two bananas and a pineapple.

[–] [email protected] 1 points 3 weeks ago

"Its price," not "it's."

[–] [email protected] 1 points 3 weeks ago

https://www.wolframalpha.com/input?i=x+%3D+1+%2B+0.5x

[–] [email protected] 1 points 3 weeks ago

About tree fiddy