this post was submitted on 23 Nov 2024

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Math Memes

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Simplify (sh.itjust.works)

submitted 1 month ago by [email protected] to c/[email protected]

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[–] [email protected] 171 points 1 month ago (1 children)

For those of you who were confused even after reading the comments: (a)(b) basically means a*b. My mind just didn't connect that to the fact that (x-x)=0. in the (a-x)(b-x) stuff is also (x-x) which = 0, and anything * 0 = 0, so no matter the value of literally everything else in the equation, it all equals out to 0 because every single () will get multiplied by (x-x), which is 0. There, hopefully that will clear it up for anyone remaining lost. And like all good jokes, they are always best when you have to explain them.

[–] [email protected] 2 points 1 month ago (3 children)

(a)(b) basically means a*b

Ok, wtf. Why write it like this then?

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

To make sure what's inside the brackets is resolved internally before they're multiplied with each other.

 (a)  (b)   =   a * b  
(a+1)(b+1) =/= a+1*b+1

[–] [email protected] 1 points 1 month ago* (last edited 1 month ago)

TIL this notation makes it math the text up

(a)  (b)   =   a * b  
    (a+1)(b+1) =/= a+1*b+1

Edit: hmm, already shows in a code block so adding backticks didn’t do anything

[–] [email protected] 7 points 1 month ago* (last edited 1 month ago) (2 children)

To expand on what superkret said, in math there is the concept of "order of operations". That is to say, every function in math (add, multiply, divide) has to be done in a specific order. Since multiplication comes before addition and subtraction, if you have a formula like a-x*b-x, you will do x*b first, then a minus the result of x*b, which would give a very different result than if you did a-x and multiplied that by b-x. This is where the parenthesis come in. You are basically saying, resolve every section in parenthesis first using the proper order, then resolve the rest.

My original example (a)(b) was over simplified, because there is no conflict there. You can also do things like (a*x)-(b*x). If there is no operator though, it is assumed multiplication, and I'm unsure why that is.

[–] [email protected] 4 points 1 month ago* (last edited 1 month ago) (1 children)

Putting multiple asterisks in a comment makes it look italicized, at least on some Lemmy clients. If you want to have asterisks with *unitalicized* text, you gotta put a \ behind the * to negate the change

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

Oops, I should have previewed it, thanks for pointing it out.

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

Because you wrote a lot less when writing it this way. Groups of terms beside each other are multiplying each other and you have to solve what's inside of those groups before multiplying them together.

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

Groups of terms beside each other are multiplying each other

Actually the whole thing is a single Term. Terms are separated by operators and joined by grouping symbols, and there's no operators between the successive brackets.

you have to solve what’s inside of those groups before multiplying them together

You don't have to, but it sure makes the working-out a lot easier if you do!

If a=1, b=2, c=3, d=4, then...

(a+b)(c+d)=(ac+ad+bc+bd)

(1+2)(3+4)=(1x3+1x4+2x3+2x4)=(3+4+6+8)=21

whereas...

(1+2)(3+4)=(3)(7)=(3x7)=21 :-)

[–] [email protected] 87 points 1 month ago (2 children)

For those that struggled like me…

Going from a-z, write out the last three multiplicands.

[–] [email protected] 52 points 1 month ago (1 children)

X-X

[–] [email protected] 2 points 3 weeks ago (1 children)

For those of you who still struggled like me, a multiplicand in this case refers to one of the (n-x) terms.

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

a multiplicand in this case refers to one of the (n-x) terms

Well, that's what was apparently meant, but in fact the correct terminology here is factors. There's only multiplicands (and multipliers) with an explicit multiplication sign. axb - multiplicand a and multiplier b, ab - Term with factors a and b, and a is the coefficient of this Term.

[–] the_tab_key 52 points 1 month ago (24 children)

Even if the x-x term didn't exist, the equation is already simplified (fully factored) so there is nothing to do anyway.

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[–] [email protected] 46 points 1 month ago (2 children)

Fun fact, omitting the (x-x) zero term and expanding the entire polynomial, you'd get something with 2^25 = 33,554,432 terms. May be slightly excessive!

[–] [email protected] 8 points 1 month ago (1 children)

Couldn't you combine a lot of like terms as you went along, though? A polynomial of the order x^26^ would only have 27 terms.

[–] [email protected] 2 points 1 month ago (2 children)

No, because each coefficient is its own variable; they're not constants.

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

because each coefficient

There's only 1 coefficient - in this case it's (a-x) - the rest are just factors.

they’re not constants

They could be - we haven't been given that information.

[–] [email protected] 1 points 1 month ago* (last edited 1 month ago)

Huh, I'm so used to polynomials being in the form ax^2 + bx + c that I never considered that every letter might be a variable.

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

33,554,432 terms

Actually it would be that many factors. The whole thing is a single Term.

[–] disguy_ovahea 40 points 1 month ago (2 children)

This was impossible to answer prior to 3 BC.

[–] [email protected] 15 points 1 month ago

Unless you were Mayan. They had a concept of zero, or so I heard. But they lacked the letters, a-z and the parentheses :p

[–] [email protected] 1 points 1 month ago (2 children)

Why?

[–] [email protected] 35 points 1 month ago (2 children)

0 wasn’t invented yet.

Mesopotamians invented it because year 0 was approaching, so there was a dire need to represent such number.

[–] [email protected] 1 points 1 month ago

TIL they had ghost concerts back then

[–] TempermentalAnomaly 1 points 1 month ago* (last edited 1 month ago)

0 BCE kind of sucked. Thankfully, they figured it out and 0 CE was awesome.

[–] disguy_ovahea 5 points 1 month ago (1 children)

That’s when the number 0 was introduced in India.

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

Ah, I forgot zero was so recent.

[–] [email protected] 12 points 1 month ago (1 children)

Solution?

[–] [email protected] 64 points 1 month ago (12 children)

There’s an (x - x) in there

[–] copd 10 points 1 month ago* (last edited 1 month ago) (2 children)

Technically there is a (x - 𝑥) in there. U+1D465 != x so this post is a little meh

[–] [email protected] 11 points 1 month ago (2 children)

Mathematicians do weird stuff to get more letters, but I've never seen anyone use x and 𝑥 for different things

[–] [email protected] 5 points 1 month ago

I've never seen anyone use x and 𝑥 for different things

Yeah, me neither. I have had situations where I needed to distinguish between u, v, nu, and upsilon though. I had to be very careful with my handwriting that day...

[–] joshthewaster 4 points 1 month ago

They also wouldn't want to be ambiguous. If I was trying to write this problem the a, b, c... would get replaced by something like a_1, a_2,..., a_26 to be clearer. This problem works as a fun gotcha but isn't something that would come up in the real world.

[–] pyre 1 points 1 month ago

the first variables aren't roman. they're italicized as well. idk where you're getting the x vs x thing.

[–] [email protected] 6 points 1 month ago (1 children)

duh...

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

Do do, do do do do do....

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[–] [email protected] 5 points 1 month ago

[–] [email protected] 2 points 1 month ago

Now I want pie.

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