r/learnmath

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Guys, I was randomly playing with numbers and noticed something weird lol.

3 + 3/2 = 3 × 3/2

Both give 4.5. I got curious and started checking if there is any way to generalise this.

So I started with

a + b = ab

Then rearranged it:

ab - b = a

b(a - 1) = a

So,

b = a/(a - 1)

Then I realised I can take almost any number and find another number which satisfies this.

For example, if I take 8, then b = 8/7.

8 + 8/7 = 8 × 8/7 = 64/7

I also tried another approach. If I say both the sum and product should equal some number c, then

a + b = c

ab = c

Using the quadratic formula, I got

a, b = (c ± √(c² - 4c))/2

So if I choose c = 88, I get two numbers whose sum and product are both 88.

I know this is probably already known maths and not some new discovery haha, but I was happy that I managed to derive the formula myself.

Is there any particular name for this relationship, or anything interesting related to it? Just curious if this leads to something else.

I wanna hear your perspective about:
- the difference between "correlation" and "standard deviation".
- where to use each one

need advice if someone have suggestion or ideas how to be more sustainable and probably spend less money over time.

i like to practice math, and might be a bit annoying but i *need* to do in nice papers with nice pens. i feel like my adhd and ocd combined plays a huge part into this. + i love to draw as well. so drilling math problems in a nice sketch paper with nice gel pens or sharpie felt tips just hits different. somehow i don’t get frustrated and miss a lot of algebra details (my biggest issue with math).

i tried to just do simple lined notebooks, never ended using it i get frustrated and missed a lot of algebra details. if it’s wrong pen it’s also very icky to practice. i have an ipad pro 11inch with apple pen that i never ended up using, even tried to buy a different “paper-like” screen protector for ipad and somehow still frustrates me.

now i’m using sketch books (broken white instead of plain white color), no lines, with a very nice pen (went through three different type of pens) and i would spend hours and hours drilling/practicing with no troubles. yes i wld still miss some algebra but way less compared to under different conditions, and i just get less frustrated because somehow its still satisfying to draw graphs with the sketch papers and a nice pen.

please or maybe someone just need to tell me it actually isn’t that wasteful … 😔😭

Expressions for Pi are often stated as being accurate up to n places. For example, 22/7 is stated as being accurate up to 2 places. So is there some gold standard expression, like an infinte series, against which other expressions are tested for accuracy. Since Pi is transcendental how do people know that this gold standard is most accurate?

Sooo, as the title says, I am a freshman who joined university this year. I am a management major. And it’s required to pass calculus 2. The problem is I am like veryyy much struggling. I am not THAT bad at math. I used to solve high school problems with not much difficulty.
- our first cal class started with limit. However, in high school, our teacher said “you will learn this in uni anyways so ima skip” and when I entered uni professor said “you all know this right? Let’s skip” and now I’m in my 5th seminar class. In function limit? Derivatives? Yeah so I’m stuck. I tried to ask chat gpt for help. Like help me understand all of this step by step. But I still don’t understand ANYTHING. Mid term is coming. I swear I think I’m gonna fail this class.
-I was wondering does watching YouTube videos help? Reading books for a long time hurts my eyes and it makes me feel drowsy…I did go to the library and borrowed a book for 2 weeks and read it but nothing stuck in my mind.
-I believe the problem is also because i genuinely don’t like math. Just seeing at those numbers annoys me. But I do like my major. What should I dooo?

i just started 9th grade and i dont get one bit of the math. last year's math was normal difficulty for me is it just because the shift from middle school to high school? im afraid to temporarily understand the math and at the end of the year, i relearn everything and im also afraid for the rest of high school's math. if i found 9th grade hard, then what about the future?

Okay so we have been factoring trinomials for around 4 classes now and I still can’t seem to understand it. I have a quiz on Thursday and I’m convinced I’m about to bomb it. I have pages and pages of lectures we do in class but they don’t help when I actually do the work. In class it’s not so bad but when I get home and have to do homework it’s like I never learned anything at all.

It seems whenever I use the methods I’ve been taught (grouping or trial and error) I somehow mess up.

For example this problem is on my HW:

12x ⁴+17x ²+6

I have no clue where to go from here.

And then when they do proper subset they write \subsetneq

This post isn't for me, it's on behalf of my boyfriend, so bear with me as I'm not much of a math whizz like he is. We are UK based.

My boyfriend has started university as of ~2 weeks ago, he excelled in college (two A* and two A) and was accepted into all of his uni options. Maths has always been a breeze for him, his absolute favourite subject and always tries to teach me his favourite topics. Unfortunately it's all in one ear and out the other for me, but I still love to listen. But point is, he's a natural and he adores maths.

Despite this, throughout college he always ranted and raved because it was too stressful, too fast-paced, too strict, and felt like he never had any time for his work. Before anyone says it, no, he doesn't waste all his time going out or doing anything other than study. Of course he has free time, but it's fleeting and he never allows himself to truly relax and enjoy it, too worked up about the next test or topic he can't figure out.

Many people had said to him leading up to the end of college that university, at least the first year, would be a lot more relaxed. He'd have more days off (expected ~3 day weeks based on what he'd been told), and that he would be able to do things more or less at his own pace, granted he kept up with the classes.

He's been hit with mental whiplash upon starting university and discovering that it's completely different than the dream of mathematical learning he had been promised. He's in 5 days a week, 9-5 most days excluding travel, and while he seems to be wrapping his head around the teachings of his classes so far, he panics because he feels like his brain is being attacked by too much knowledge all at once, and he physically doesn't have the time to keep up with the workload. He's studying for ~4 hours a day after getting home, and only manages to fully understand one or two small parts of what his lectures had covered that day. He already has a test coming up next week that is sending him spiralling into panic.

I also wonder if he's struggling with the fact that university level maths is genuinely really hard and different (I assume!), so it's taking him longer to understand whereas in GCSE and A-levels he could figure it out as fast as a finger snap. He's stressing and struggling to sleep at night, talking about how he's only been there for 2 weeks and he's already feeling behind and part of him wants to give up. I try to comfort him and tell him that he'll find his rhythm and to allow himself time to settle in and get the swing of uni, as it's an extremely big life change regardless of what subject you take. It doesn't seem to help him.

I never went to university though, so I have no advice to give him about how to make it easier on himself and tackle the workload in the most efficient way without causing burnout or stressing so much. That's why I'm writing this post in hopes that the people in here, with considerably more experience than me, might be able to offer some advice that I can pass along to him so he can start to find his feet again.

Any advice regarding handling the change to uni, dealing with the stress levels, and keeping up with the workload would be appreciated greatly.

Tldr; Boyfriend struggling to handle maths in university, says the workload is too much and he has no time to keep up, extremely stressed about falling behind and failing. Advice for settling into uni and tackling the workload appreciated.

Question: How many batting orders are possible for a 9-person baseball team where each team member gets one time at bat?

I’m doing permutation questions but Why is the notation 9P9? My first guess was 9P1. I guess Im also having difficulty understanding the question itself.

Thank you!

Hi everyone! I'm excited to find this subreddit. I've been interested recently in learning math. I'm in my 40s, no reason to do it other than I think it's interesting. I didn't have great math teachers in school. I'm very self-motivated so I'm kind of hoping for textbooks that people have liked. What textbooks are the best and what order should I go in? I seem to remember in school we did algebra, then geometry, then calculus. Also, I'm interested not just in doing the math but in understanding the story of how it all fits together, conceptually and historically. I would really appreciate any and all recommendations!

This has happened all my life when I got diagnosed with an info retention disorder, I have always struggled at remembering math and formulas, but I can easily do English, right now I am in Trigonometry and I am struggling so badly right now trying to understand everything, I don’t know how to simply just learn it as I have had this issue for a long time, any recommendations would help.

So, I'm in 9th grade and my math is absolutely bad and I don't know how to improve it. Ig I gotta get better at it for future n stuff. I really don't know what to start with but I know I should start soon cause I don't have much time.

I have bad basics and I have been failing at my tests in school I do good in other subjects but it's just math idk I fear maths or something. Please help me🙏