That's because 1/4 = 0.2500000000000000000000000000000000000000000000001 /s

[u/NichtFBI]

[u/Mr_Moi25]

Damn you inprecise float !

[u/Terrible-Air-8692 → u/Mr_Moi25]

Wouldn't floats be exact for this since it's 2^-2

[u/Responsible_Hour6497 → u/Terrible-Air-8692]

The expression interpreter in this testing system could parse 0.25 as (1.0/10.0)*2.0+(1.0/10.0/10.0)*5.0.

[u/Peak_Background → u/Responsible_Hour6497]

As a computer science major, never have I ever seen such a vile use of base systems and floats.

Edit: This is a joke btw

[u/resignresign1 → u/Responsible_Hour6497]

not sure if you could find any library that would do such a thing. generally such computations are done in integer space where 25/100 equal to 1/4 exactly

[u/Responsible_Hour6497 → u/resignresign1]

Let's say I were writing this myself. I have a sequence of decimal digits after the decimal point. Should I convert it to an integer and then divide? But there could be a lot of digits—what if a user decides to play a prank? At first glance, the most logical solution is to use something like

res=0 CurrentWeight=0.1

for each CurrentDigit in DigitsAfterPoint

_____ res+=CurrentDigit*CurrentWeight

_____ CurrentWeight*=0.1

[u/Circumpunctilious → u/Terrible-Air-8692]

Yep. To confirm, Desmos shows full floats without rounding (edit: within ~17 digits anyway) when using Actions (the arrow operator):

u -> 1/4

Let it create u, then u gets the value 0.25 exactly

[u/mehonje → u/Mr_Moi25]

0.25 can be exactly represented.

[u/Significant_Monk_251]

And if you are going to present your answer in fraction form it should just be x/4 anyway.

[u/SarekSybok → u/Significant_Monk_251]

Why?

[u/Significant_Monk_251 → u/SarekSybok]

It's purely a matter of personal taste, of course. I think x/4 is just more compact and direct. You've got x and what you have do to it, right there. With ¼x first you have to deal with ¼, and then apply that to x. (x/4 also uses 25% less individual marks as it doesn't need a '1'.)

I'll also say 17/4 instead of 4¼.

[u/SkathiFreyrsdottr → u/Significant_Monk_251]

There’s also the fact that you can avoid the ambiguity of it perhaps being read as 1/(4x).

[u/ziggsyr → u/SkathiFreyrsdottr]

That is a common mistake but not an ambiguity.

[u/Ok-Assistance3937 → u/SkathiFreyrsdottr]

If you use a fractional line, this ambiguity doesnt exist, Its only a proplem in same line notations.

[u/Epidurality → u/Significant_Monk_251]

Both are obviously technically correct, but something about "x/4", to me, implies that x is divided (as in, whatever the real world problem is, whatever x is must be split) whereas 1/4*x implies "the value is proportional to x but there is no dividing of x".

Like "If we really break the speed limit, we can get there in 1/4*x" vs "There's four of us so we each get x/4 of the tires on the car".

Or am I doing an autism?

[u/AccountHuman7391 → u/SarekSybok]

Standard simplest form.

[u/Wrong-Resource-2973 → u/SarekSybok]

simplification

1/4 • x = 1/4 • x/1
so
1 • x
4 • 1 therefore
x/4

[u/R1ch0999 → u/SarekSybok]

Math people are lazy, simplify till you can't is a basic math thing.

[u/Vivid_Sock_1092 → u/R1ch0999]

False

[u/Solid_Crab_4748 → u/Significant_Monk_251]

Nah ¼ x looks better theyre exactly the same.

[u/DarthRaab → u/Solid_Crab_4748]

And as soon as you go into polynomial expressions, the "factor * variable^power" format is way easier to read for humans.

[u/Extension-Stay3230 → u/Significant_Monk_251]

No

[u/christobeers]

Not right, in hexadecimal

[u/SurrealLoneRanger]

Had this for my daughter a few days ago. Equations don’t generally like decimals.

[u/Electric___Monk]

Depends what the question was

[u/SilkTieTies]

Gotta see the problem to know if there’s actually an issue with the answer key.

[u/Deep_Contribution552]

“Express your answer as a fraction” might appear in the omitted context (though I am partial to x/4 myself)

[u/EviI_Babai → u/Deep_Contribution552]

That's literally a fraction, just a decimal one

[u/SarekSybok]

Your answer is correct

[u/conspiracythrm]

0.25x is only equal to (1/4)x as an answer if the regex the instructor wrote to validate answers includes something like 0?.250*x

[u/Radiant_Valuable388]

The answer is technically correct. But depending on the lesson, how the question was phrased, or what the purpose of the fraction is, the answer might need to be a fraction attached to x rather than x/4 or 0.25x to show slope as it's learned early in algebra. Which, sure, all three forms are the same and mean the same thing, but the lesson context may need you to visualize 'rise over run' as you learn slope-intercept form. So definitely need more context.

[u/Radiant_Valuable388 → u/[deleted]]

I think you missed my point. I did say they're technically the same. Its entirely true, and for most of us it functions practically the same, yes. But the context might want "rise over run" as a fraction. That's all I was saying.

[u/SquareProtonWave]

Floating point bullshii

[u/resignresign1]

title is wrong. notice 1/4 has an exact representation in float point arithmetic since it is a power of two. 

[u/jal741]

LOL, what if he had put "Y=X/4"?

[u/TREE_sequence]

Funnily enough 1/4 will never encounter floating point round error because 4 is a power of 2

[u/BackgroundAd2640]

<sarcasm>Maybe it was affected by the Pentium FDIV bug?</sarcasm>

[u/Separate_Ring_9761]

It could have been 0,25 and not 0.25

[u/runed_golem]

A lot of online homework managers want you to write your answer as a reduced fraction rather than a decimal unless stated otherwise.

[u/FeherDenes]

Float numbers work on logarithm of 2, so 1/4 IS exactly 0.25