/sci/ - Science & Math

>>6223427
(x+y)(x+z)

that's your starting point.
y and z add up to make the x coefficient, and they multiply to make the number coefficient

so, for example i'll just randomly pick that 2nd question:
<span class="math"> x^2 +13x + 42 [/spoiler]
so you wanna multiply to 42, but add up to 13
well, that's easy, 6 and 7

so it's (x+7)(x+6)
you just do it by observation ,and also by not being a retard and ACTUALLY KNOWING YOUR FUCKING TIMES TABLES FOR ONCE!
which yeh, you should have done like several fucking years ago, so get on it.

>>6223436
I was asking for TRICKS.

Like with ones where the constant (42, in the 2nd problem) has so many factors and none of them add to equal the x coefficient, what do I do? Do I have to test all 8 equations?

>>6223451
You do it by observation. As you get better at this, you'll be able to pick up the patterns faster. This kind of stuff is not easily solved through rote algorithms and is a big computational problem. Much of mathematics is concerned with solving these things efficiently.

>>6223451
you do enough, you'll just know it by instinct.
nowadays i look at a quadratic, and if it factorises then i immediately just know it. it's like i'm a fucking math-jedi or something.
shit's pretty cool, but yeh, i had to work at it
point is: you're gonna need to practice

>>6223451
You could just use the quadratic root formula or whatever its called

>>6223458
> Much of mathematics is concerned with solving these things efficiently.
fuck efficiency, just build be some muthafucking faster computers, faggot

>>6223459
that way is SO FUCKING SLOW
if it factorizes, then doing it by observation is way better than using the fucking quadratic formula

>This takes time
Get good kid.

>I was asking for tricks.
Look at 42 and then 13. You understand that (x+y)(x+z) leads to y+z and y*z correct? One of them is a product, the other a sum. Naturally, the product is bigger. If y and z are almost the same, you can check.

Square root of 42 is 6.8 ish, 2 times 6.8 is approximately 13. This works, so the two will probably be really close to eachother and the square root of 42. (answer, 7 and 6).
Note this doesn't work if the last term is opposite of the first terms sign (x^2 + x - 6x).

its 9 questions, just do it rather than to crowdsourcing it... jeez

>>6223464
> (x^2 + x - 6x).
you still get that by instinct. so 3 and 2. one of which is a minus sign (i'll work that out at the checking stage because fuck you)

also, you're square root method is pointless and slow as shit. how many things actually even go into 42??
6 and 7 immediately come to mind
maybe 14 and 3 as a second, but then i see that they dont add. and i thought of 6,7, first anyway.

>>6223457
How long would you say before I get this good?

Not really its just plugging in numbers, it will always factorize you might get complex numbers thats why you should just use the formula, the rest is just basic arithmetic

>>6223468
Fuck you kid, i didn't mean pull out a calculator and check the decimals on the square root, just look at it and see which squares it's between.

For example, x^2 + 19x + 88. 88 is between 81 and 100, so 9 point something. 9 times 2 is 18, really close to 19. Therefore check values that divide 88 that are really close to 9. If it was way off, then check values far away.

>>6223473
dunno, depends on how retarded you are. i had times tables drilled into me as a kid, the full 20:20 shit, so that's the full 400 to fucking memorize
at the time i fucking hated it and it pissed me off
turns out it's pretty damn useful (also, all the ones above 20 you can do by simple splits, so if someone makes me do (17X34) then you can just do the 238 + 20X17
takes a bit more time with the addition, but aint too hard.

also, most things dont factor into much. you get some cunts liek 128, and you're like FUCK YOU 128! YOU AGAIN YOU CUNT! because it splits too many ways and consumes my very important time, but usually you can tell. a lot of them only split like 2 or 3 ways, some of which end up being way more common than others, and you just get used to the patterns of it.

>>6223480
dont call me 'kid' you fucking pleb!

>>6223480
also with <span class="math"> x^2 + 19x + 88. [/spoiler]
i instinctively try 22 and 4.
shit, that's one away
kk, then maybe 11 and 8
hah, got it

point is that your fucking 'square root' method is pointless as fuck because quick-think TaE is far faster than whipping out the fucking calc, so go gargle some bollocks, cumdumpster

>>6223492
and how does your genius mind act when you have
x^2-3x-11
?

just askin'

>>6223502
well 11 is prime so seeing as it aint 10 or 12 i'll have to QC
<<<
irritating, but hey, if it dont factorisze, aint my fault isit?

>>6223504
*QF
sorry, typo

>>6223504

But it does factor, all quadratics will

>>6223508
>all quadratics factor
<<<

>>6223510

>thinking quardratic factors imply they are Integers
>not realizing this this is a factor

ax^2 + bx + c = (x+z1)(x+z2)

Have fun in high school

>>6223511
Not every quadratic equation has roots. For example x^2 + 1 = 0 cannot be solved. Did you fail your calculus class?

you need yourself some Maple, OP

>>6223510
Give me an example of a quadratic that can't be factored

>>6223517
0/10
confirmed troll
gr8b8m8

>>6223519
532743x^2-76547658475x+7843
:D

>>6223511
*A(x+z1)(x+z2)
lol you made a mistake

>>6223517
(x+i)(x-i)=0

>>6223517
that is clearly i and -i, also what does this have to do with calculus?

>>6223517
>Cannot be solved
(x + i)(x - i)
Oh wait, you don't get to i in middle school.

x^2 + 2x + 4 = 0
(x-a)(x-b)=0

a+b=2
a*b=4

2 equations 2 variables => SOLVE THAT SHIT

>>6223526
<span class="math">
\left(x-{\frac {76547658475}{1065486}}-{\frac {1}{1065486}}\,\sqrt {
5859544017988526112229}\right)\left(x-{\frac {76547658475}{1065486}}+{\frac {1}{
1065486}}\,\sqrt {5859544017988526112229}\right)
[/spoiler]

>>6223536
a+b=-2

>>6223536
b = 4/a,
a + 4/a = 2
a^2 + 4 = 2a
a^2 - 2a + 4 = 0, doesn't result in real answers (I won't post the technical ones to not confuse you).

>>6223537
wow, you fucking autist. i aint gonna check that. even if it is right, i dont like roots in my fucking brackets.
i'd just leave the answers as numbers and round them. root brackets are ugly as fuck.. my math has to be right AND look good (like me. :D)

>>6223537
Hahahaha

>>6223571
>you fucking autist. i
hum.
do you know wolfram alpha? Can be useful

>>6223571
it took me literally 10 seconds to solve this and convert the answer to latex code

>>6223577
>>6223581
>translation: i cheated
..oh fuck you!

>>6223571

the only autist here is you

>>6223591
>no you
[sarcasm] oh shit, that's an epic burn right there. i can see you're clearly the brains of this board. i'll know not to try to mess with you in future [/sarcasm]

>>6223594

>>6223598
indeed i will, but unfortunately for you, not for several more years
<<<

>>6223601
You will? If you're ready, can you notify me? We could do it together.

>>6223618
nah, it's strictly gonna be a solitary thing. i aint gonna be feeling particularly social at the time, as im sure you realize.

seeing as you probably hate me anyway (most people do) i'll just advise you to not get your hopes up coz this aint gonna happen for many many years. probably decades. i just aint fussed with getting old and having diseases stack up on me like a bitch.
that's mother natures way of saying "YOU'VE LIVED ON MY PLANET TOO FUCKING LONG, GTFO!!"