/sci/ - Science & Math

>he fails his math classes

>mfw he thinks he's really good at math

http://projecteuler.net/index.php?section=problems&id=1

Do all of these.

>>2948792
I fail most of my classes. this does not have any bearing on how smart I am.

i've never gotten below a 92 on a math test.

i've never studied.

3rd year university writing a publication.


mfw you're nothing.

>>2948799
..................oxymoron much.

>>2948799

keep telling yourself that. if you fail your classes, you're not good at the subject, why is that so hard to accept? you're just one of the other 50 million dumb fucks who thinks the reason he failed in life isn't because he's dumb

>>2948797
wtf? Am i supposed to do that in my head?
hurr durr, 3x3 is 9, 3x4 is 12, 3x5 is 15. See you guys in a little while!

>>2948799
Yes it does.

>>2948812
No those are programming problems. You're meant to write computer programs to solve them all. But many of them require deep thinking and you have to be smart about how you solve some of them. Especially the further down the list you get.

>>2948774
See if you can sit in on a math 300 level course somewhere for a day or two. A proof course, or intro to proof course, will show you if you have what it takes to think of math creatively. You might be crippled by your lack of foundational study. Yes, the early stuff is boring as hell. But you need those tools in the toolbox both to solve problems as well as to communicate to your peers. They also provide additional insight to how numbers work.

>>2948810
but, but, but, I got a 34 on my ACT, and a WAIS-III equivalency of 137.
>Implying high school and freshman college math is important
I do very well in classes I am interested in. Don't worry about me I just want the fucking math problems.

Math is a lot like chess. You just need an analytical mind- which many people have. That being said, the only way to get past that basic stage is by training, which requires a lot of knowledge that you have to pull out in the most odd situations.

I would have recommended the 'art of problem solving book', which requires only geometry and such, but even that needs training- you can solve it if you put many hours into it, but that's not worth it. Still, obvious choice if you don't want rote memorization.

If you want calculus problems, try 'problem solving' in the sections of stewart's book, and compare your answers to the ones in his solutions manual.

Anyways, you should feel safe that you have a logical mind. Math is not an IQ test- it's not supposed to be innate unless you're in the 0.0001% of people, which STILL doesn't give you a total advantage against someone who is not in the range yet has prior training (basically, you just learn faster). Everyone hates it, but you still have to do rote memorization, which doesn't mean zombie-like studying. Rather, it's more like you understand a really long and huge puzzle and you have to memorize the clues that put it together. There's some quote by terrance tao or whatever, im too lazy to find it.

>>2948812

>brute forces problems
>thinks he's good at math
>laughinggirls.jpg

>mfw he can't memorise a few simple formulas and ideas

>>2948817

Is this the answer?:

int main {

int sum1, sum2, final;
sum1=0;
sum2=0;

for(int count=1; i>100; i++) {

if (count%3==0) {

sum1=sum1 + count; }

if (count%5==0) {

sum2=sum2 + count; }

}

final=sum2+sum1;
cout << final;

>>2948774
Here's a math problem for you, that will test your reasoning skills more than your formula memorization.

Which natural numbers are sums of consecutive smaller natural numbers? For example, 30=9+10+11 and 31=15+16, but 32 has no such representation.

This taken from the introduction of "Mathematical Thinking." Do your best to prove your result.

>>2948830
Thanks for the well thought out response. I guess I was never taught in that way, because if i follow what's actually (actually) going on then i have no problem. I never really learned trig, but i remembered enough to figure it out and use it at my job when i needed to.

>>2948774
Ok here's a problem. You have a set of n circles each of which are positioned such that if you connect their centers, you obtain a regular n-gon. Find an equation for the area inside these circles for n>=2.

Write out a formula for the roots of the equation <span class="math">x^5 - x -1 [/spoiler]

>>2948830

For me, rote memorization was never the greatest asset. I tried remembering the quadratic formula for a while, but I kept forgetting it certain parts of it(i.e., like the negative in front of the b or the 2a part) when I was younger. When I was finally introduced to an amazing professor, I learned the best way to learn mathematics is to derive the solution yourself. Although I've memorized the quadratic formula, it's pretty easy to derive it. I know it now because I can produce it.

>>2948871
I find this problem requires analytical thinking because you have to try and generalize to n circles. You obviously can't just solve it out for every number n.

>>2948883

Results don't mean shit in math. Arguments, examples, and counterexamples are the blood and guts of mathematics.

>>2948860
>>2948860
um, 26 is
35
34
38
33
how is this not just addition?

>>2948898

You're supposed to describe a set A of numbers so that everything in A can be written as a sum of consecutive integers, and everything not in A can't. Nobody gives a fuck that you can write down four or five examples. Proofs, fool. Proofs. Give them to me.

>>2948898
read, man. Prove your result as best you can. This is where the math comes in. Is 3,566,677,235 one of these numbers? It gets hard to tell intuitively. You're looking for the ENTIRE set, which might be infinitely sized. This is math, not just finding a few specific cases.

>>2948898
Obviously you're meant to find an algorithmic way to determine if a number is capable of being written that way. Not just go through a list a few. I would start by looking at what numbers you can get if you just start adding sequential numbers.

>>2948895

Okay? What does that have to do with anything I said, though?

>>2948898
trollingorjustreallystupid?.jpg

anyway dude you're shit. gnight all it's 4AM
'

>>2948900
Ignore him. He just wants to feel superior by claiming he knows what math is really about and saying you don't.

>>2948871
Anyone want to take a crack at my problem?

We have given points: M=(-1,3) and N=(2,5)
On the x axis find such point A, for which sum of its distances from given points is the smallest. Do this without calculus.

>>2948901
and what does an algorithm look like?
does it have anything to do with the fact that it's easy to reach 16, and 32 is not one?
im gonna go out on a limb and say 68 is not in the set?

>>2948900

It has everything to do with what you said. The quadratic formula is obviously useful. My statement was a bit more poetic. You understood it best when you realized that the monstrous looking equation that evidently came from nowhere was actually born from a very elegant technique of solving quadratic equations. When you understood how to derive the quadratic formula, that was doing mathematics. Any monkey can plug shit into formulas. It takes a mind to be able to produce those formulas and to understand the mathematics that produces them.

>>2948910

And you can suck a giant dick. I want to tell everyone about what math is and share it with the world and make it as accessible as possible as anyone.

>>2948920
Lemme make sure I understand it. You take n circles, and overlay them so that their centers create the vertices of the respective n gon? So, if n = 3, it looks something like a venn diagram, and we're trying to find the area of the center intersection?

>>2948810
I failed school , every class of it because I was bored and hated school.
Basically, I wasn't listening, wasn't doing any homework. So I didn't really "fail" , I chose not to success.
Funny how your superior mind can only think in binary solutions (not telling about the fact that you have obvious ego issues, like most of the lower intellectual classes of people.).

>>2948928
>>2948928
>>2948928
3 and 2/3? i just did it in my head and it seemed way too simple.

>>2948930
But thats the point though, you're supposed to figure out the algorithm. You're the one who wanted math problems to test your analytical skills, you figure it out.

>>2948928
>Do this without calculus.

Always hated questions like that. If you can do a problem quickly and efficiently with calculus or some other mathematical operation then using it is fair game. I know they're about thinking outside the box etc etc but it's just a crap format for a question. Mathematics moves on, evolves. It's like people crying about Fermat's Last Theorem being proven using modern mathematics and how 'that's not how Fermat would have proven it'. If you want it solved using basic operators then do it yourself cunt.

>>2948943
Sorry, I should have specified that they should each only touch at one point. In other words you'll have an area in the center which is no contained in any of the circles but which is still bounded by all three. I'd draw a picture but I cant on this comp.

>>2948951
Not the person who posted the problem, but that is just blatantly wrong. That point would be to the right of both points and obviously then it can't be the minimum distance from both. If you're OP you don't seem to be as good at math as you claim you are.

>>2948930
For your purposes an algorithm is the pattern you can follow to arrive at an answer to any specific answer. Doing long division by hand is pretty much an algorithm.

I'll start you off. You're not entirely on the wrong track, but you're focusing on explicit numbers a little much. Are odd numbers greater than one EVER in the set? Why or why not?

>>2948951
Nope

>>2948968
Another way of saying it is, if you're circles all have radius R, then the length of a side of your n-gon will be 2R.

>>2948975
LOL, i got x and y axis confused

>>2948968
Oh, okay. I understand. The area we're trying to find ends up being in the shape of an N gon with curved in sides. I'll do some cogitating.

>>2948999
Yes pretty much. It took me about 30 minutes to derive a general expression the first time I did it. The best method is to do a few specific cases and then try to generalize it.

>>2948979
OP here. definitely between 2 and 3. closer to 3. I have no fucking clue how to reach an answer to that.

>>2949017
Are you stupid? Read my last statement. >>2948975. You're point can't be to the right of both points. It HAS to be somewhere between -1 and 2. That much should be obvious.

>>2949028
.5?
fuck math I'm done. I remember now why i never pay attention.

>>2948969
>>2948969
I told you not to use calculus, because we had this to solve before even knowing what calculus is.

>>2948860

Not OP, probably even more retarded than OP, but I'm going to try this.

We're looking for all natural numbers such that X = (n) + (n-1) + (n-2) where n is a natural number. We know the restrictions on n have to be such that it's equal or greater than 3, which gives us our first number, 6. Now we can continue plugging in 4, 5, 6 etc. so that we get 9,

wait, I looked at the question again and realized we didn't need to have 3 consecutive numbers, I only looked at the first example, shit.

Is doing something with n + n-1 on the right track? Have I even got to the track yet?

>>2948860
I'm interested in this problem. Is it something to do with expressing the number as the difference between the squares of the first and final numbers in the sequences? I can write down an equation for the sum of a series, but I can't immediately see any properties that arise from it.

>>2948928

I don't feel like doing this but am I thinking about this correctly? Find the midpoint of the two points then find the line perpendicular to the line of M and N that goes through the mid point? Then see where it intersects the x-axis. Tell me if I'm wrong.

>>2949049
You overdid this a bit

>>2949036
Yeah... you might have a logical mind, but if you don't have the attention span to solve problems your issue isn't with formula memorization. The vast majority of these problems require very little previous understanding of mathematics.

In the addition one, it should be fairly evident to anybody creating a few cases that odd numbers are always expressible as the sum of smaller numbers. if X is odd, X can be expressed as X/2 (round down) + X/2 (round up). Finding the relationship between odd numbers and being divisible by two, you might have pursued and investigation between numbers divisible by three, four, etc. It doesn't require calculus, it just requires patience and the ability to not only notice patterns, but figure out what those patterns have to do with the situation at hand.

I don't think math is for you.

>>2949049
Not the person who posted the problem, but I would approach it by looking at all the numbers you can get by adding values. In this way you know what numbers can be represented by that and then obviously the rest cant. Often in math, the inverse of a problem is easier to solve. Such as if they say, find when A is true, it is often easier to find when A is false and then you can then know when A is true.

>>2949059
Sorry. You're wrong. This would be true only if y_M=y_N

>>2948946

Not who you're responding too but you sound like a twat. Failing does not require intention. I wouldn't argue that you 'chose' not to succeed. But choosing not to succeed is failing in this case, because in all likelihood the goals you have require that you had succeeded.

>>2949063

I don't see any other way of going about it. Unless you mean you want me to go 1 + 2 = 2 + 3 = 3 + 4 = 4 + 5 = etc. I guess that could work actually. Then I'd have to go 1 + 2 + 3 = 2 + 3 + 4 = . Right?

>>2949102

separate all those additions by the way, I just didn't put the answers in for 1 +2 = etc.

>>2948860
Saw this thread and going to take a stab in the dark here.
It can be solved with modular arithmetic, can't it?

>>2949102
Ok, here it goes:
(x-1)+(x)+(x+1)=a where a,x are natural
3x=a they both are divisible by 3
so a=3b

>>2949102
Just adding up the numbers below 10, it looks as if 2,4 and 8 can't be made.

Is there a general property that powers of 2 can't have this done? After all, the example was 32 which = 2^5

O.P admits he is ignorant about math. Op then says he has a smart ''math mind''. . Op doesn't understand the contradiction.

There is no such thing as a ''math mind''. Being good at math isn't simple ''plug and chug'' it's understanding wtf you're doing with the math...-- Math didn't develop in a void, there were specific problems that had to be solved for us to advance in physics, these problems spurred the creation of new math theorems..

All of the complicated theorems in mathematics build off of basic assumptions, if you don't understand the aspects of calculus-- there is something fundamental about algebra you didn't grasp.

>>2949077
Logical fallacy.

If an athlete doesn't participate for whatever reason, can you say that he runs slower than the 3 first ones who were in the contest?

"Failing" school, for me, is when you try to succeed but, for whatever reasons, can't.

I didn't fail schoo.

>>2949134
>If an athlete doesn't participate for whatever reason, can you say that he runs slower than the 3 first ones who were in the contest?

No. But you CAN say he doesn't run faster.

Consider:
(n-x) + . . . + (n-1) + n + (n+1) + . . . + (n+x)

In this sum there are always an odd number of elements. Elements in the left and right will cancel out. You're left with a*n, where a is the number of elements in the sum. An example of this is 3+4+5, which is 4+4+4, which is 3*4.

Of course, you can do this with even elements as well. 4+5+6+7 = 5.5*4.

I don't know if this is useful, but it's an observation.

>>2949144
Excuse me?
No, you can't. You need results.

>>2948969
>It's like people crying about Fermat's Last Theorem being proven using modern mathematics and how 'that's not how Fermat would have proven it'

A more prominent example is the proof for the four color theorem.

>>2949144
>>2949134
>>2949136

That's actually not quite true. A better example would be to say that you have not passed a course you have not taken. In your case though 1. you literally failed the courses you took (if you hadn't taken them it would still be a bit contestable) 2. Even if you didn't take them you still didn't pass them which implies failure in the sense of lacking success.

>>2949155
>Excuse me?
>No, you can't. You need results.

God was here. Thanks for justifying my existence.

>>2949121
>>2949136

But 7 can be made. How is that possible? There is no b such that multiplied by 3 it = 7.

>>2949129
This is a good observation. I posted the problem, and I don't actually know the solution, I've never tried it before. I'd sit down and try to work it out with you guys, but I have to head to class.

The point I was trying to show wasn't that the op wouldn't be able to solve it. It was a question of whether he was willing to try, and willing to go through the effort of working out cases, finding things he thinks are true, and putting that kind of stuff to the test. This is the heart of math - if you aren't willing to sit down and do this kind of stuff you're not going to enjoy studying it.

N can be expressed as a sum of consecutive integers if and only if it has an odd divisor. PSHAWWW.

>>2948871
>>2948968
Nobody seems to have attempted this problem.

>>2949152
I think I get it. For any number


Oh wait no I don't.

>>2949184

We haven't solved the first one.

>>2949183
I HAD NEARLY WORKE IT OUT YOU BASTARD ARGGGGG

>>2949175
>But 7 can be made
>wat

>>2949163
Nope. The objectives of school isn't to input the good words or numbers in good orders, its that you're supposed to understand what's behind so you can do the aforementioned while knowing why you do it.
So, not inputing a thing on a paper sheet isn't failing.
What's funny is that you seem to want it to be a failure so much, that it makes you think that YOU are the subject of your rants.
Don't worry, daddy and mommy are proud.

>>2949207

>>2949184

If the picture in my head is what is described, then you're just cutting out N sectors of the circle with angle 2pi / N, and so the area being removed from the polygon is just the area of one of the circles. Find the area of a polygon with side length R and then subtract the area of a circle with radius R/2.

>>2949222
Butthurt

>>2949227

loljk

But you can just compute areas of sectors. Maybe.

>>2949190

can't, typo; an important one it seems

>>2949228
I have many reaction images.

>>2949227
That's not true. The area you're cutting out doesn't always add up to a full cricle. That is only true for the case where n=4 (four circles in a square pattern). So you can't just subtract the area of a circle from the area of the n-gon. Besides, you would still need to find the area of an n-gon of side length R. That is part of the problem.

>>2949249
This story of yours fills me with chills.

<div class="math">\{\frac{(i-j)(i+j+1)}{2}\vert i,j\in\mathbb{N}, j\leq i-2\}</div>

>>2949183

Not true, 31 is prime so only 1 can be its divisor. If you want to argue 1 is fine, then all numbers can be produced by this method which is not the case.

>>2949250
OP here.
why cant you just do the problem 3 times. (say n=3, then 4 then 5) then just make a graph of the results and extrapolate to the rest?

>>2949260

31 is odd and divides itself. 31 = 15 + 16.

What is your problem?

>>2949260
31 is divisible by 31.

>>2949271

Oh shit. My problem is mental ineptitude apparently.

>>2949115
Any number congruent to 0 or 1 mod 3 can be written as a sum of consecutive smaller digits.

Though I am unsure if this works, and it's more of a conjecture then a proof really.

Counterexamples?

>>2949115

Where'd the spoiler tags go?

Any number congruent to 0 or 1 mod 3 can be written as a sum of consecutive smaller digits.

Though I am unsure if this works, and it's more of a conjecture then a proof really.

Any counterexamples?

Any odd integer N can be written as the same of two consequtive integers - the ones 0.5 greater than and less than N/2. This case is trivial.

>>2949302
plenty of <span class="math">x \cong 2 mod 3[/spoiler] that can be written as a sum of consecutives

Any odd integer N can be written as the sum of two consequtive integers - the ones 1/2 greater than and less than N/2. This case is trivial.

For an even integer N we can try to write it as a sum of consequtive integers
<div class="math"> N = (k-q)+\dots+k+\dots+(k+q) = nk </div>
where k=N/2. Obviously the total number of terms added n is odd. Clearly then this procedure requires that N is divisible by n, or rather that N is divisible by at least one odd number.

>>2949336
>k=N/2
Derp
>k=N/n