#help-4
1 messages · Page 33 of 1
yez
does ge mean greater equal to?
It's my custom preamble so it won't work on you
ow 😢
You have good examples how to draw x>-4 and x>4
ts the thing i dont
You first draw a line
Take the less value, here -4 and start to draw the line with integers starting from -4
I will do the example with integers first
ty
x>-4 would have {-3,-2,-1, ... , 4, 5, 6 ...}
x>4 would start from 4 but excluding it so {5, 6, ...}
Now you can see there are numbers that one list doesnt contain
When we look for the intersection we look for all numbers that both lists contain
The list x>-4 contains also the numbers in x>4, does that make sense?
Yes but without -4 because there is no equal sign
This is where math ppl write (-4,+oo) instead of [-4,+oo)
oo
infinity
∞
i meant to mean say smth like "ooh" xd
So we put a close asymptote at -4? with like an arrow reaching to inf?
Drawing is much better because you would only have to figure where both "arrows" overlap
ic
The overlap happens when x>4
So thats the answer i needed or is there something that i need as well?
Numbers in green are also im blue contained
Well there are two more cases
The second is when the expression is 0
very well let us proceed
So you check the numerator when that is 0
The third case is when both the numerator and denominator are negative
Because dividing a negative number by a negative number returns a positive number
- x+4=0
- x+4<0 and x-4<0
Try the 3. case by drawing
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Guys I can’t understand the integrers
bro is saying it with the hard r
lol yes
Do you have homework problems involving integers
.close ok
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✅
What do you mean by this?
Like what is it used for
counting usually
the integers are 0, 1, -1, 2, -2, 3, -3, and so on
theres a lot of uses for positive and negative whole numbers
Does it solve your doubts?
it doesnt need to be in a specific order, it counts
Ok from 0,1,-1…
Ah now I understand
think it also refers to a whole number
thats just a list of things, it doesnt mean a specific order
I couldve listed them as ... -3, -2, -1, 0, 1, 2, 3, ...
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Hello, Rational Inequalities.
(2x/(x-4))≥1
further discussion from my previous one
two options to do this
- simplify the right hand side as a mixed fraction
- multiply both sides by x-4. this requires casework on whether x-4 is positive or negative
Case 3 should be
{-4,-oo} and {4, -oo}?
oh im currently in the graphing part but i did get
(x+4)/(x-4)≥0
ok so assuming this is correct, this inequality holds when x+4 and x-4 are both positive or negative (or x+4=0)
what does casework men
considering what happens under certain conditions/assumptions
option 2 is not recommended the instant your denominator becomes something remotely complicated.
and if we're being honest, also not recommended even here.
oh
if you want the multiplication route, multiply by (x-4)^2,
and instead of annoying algebraic casework, you can use wavy method
btw i meant simplify left hand side, not right hand side
i dont understand what is the wavy method
uh you need to deal with possible multiplication by 0 then
oh wait x-4 cannot be 0 or this is undefined
wavy method is identifying roots of your polynomial (in this case will be quadratic) and doing a rough sketch which pretty tells you when it's positive/negative
oh thats what it meant
but how do I apply it here
multiply both sides by (x-4)^2
rearrange until you get 0 on one side
what do you not understand in that
like how to use it
but im curr trying what he said tho
if you've understood what it is, its fairly simple to apply it here
hes also saying the same thing
I got x-4=0 and x+4=0 but x-4≠0 bcs it would turn into undefined
oh wait i didnt account for the ²
mb
Btw im doing this right?
2x²-8x-x²+8x-16≥0
=x²-16≥0
oh
ok, now factorise x^2 - 16
to identify the roots
(x-4)(x+4)
where are the roots of that
x-4=0
x+4=0
and x = what?
at those locations
x=4 and x=-4
then identify the sign of the leading coefficient to see whether you have an upwards or downwards facing parabola
i.e whether you'll have a
U or
n
shape
and draw one passing through those x intercepts
(those are the only pieces of info that matter for this)
sory 😭 but what is the leading coefficient for this?
x²?
and identify the coefficient
oh is x² itself alone a coefficient?
yes
positive?
yes
U shape?
yes
draw an upwards parabola passing through (-4,0) and (4,0)
it can be quite ugly and still serve its purpose
you don't need to worry about numerical values of stuff like y intercepts, vertex or any other coordinates
im struggling 😭
oh
ight
with this info, it should take less than 10 seconds
yeh
I was worried about the vertex
drawing by hand, you don't need any numbers on the y-axis
Pretty much draw a horizontal line
a vertical line for the y-axis (but you can actually ditch it)
dot your roots
and draw your curvy shape
and with this curve, you should be able to see when your function is positive/negative
its negative from -4 to 4
yes, where is it positive
-4 to -oo and 4 to oo
use inf for infinity
okey, -4 to -inf and 4 to inf
It took me 4 hours finally its near 😭
as it's unclear whether that includes the -4 and 4
note that you've also you've also identified earlier the restriction that x can't be 4
can you try stating the final solution to the inequality now
How do i write a final solution for inequalities
The [-4,4)?
that's interval notation, but that interval isn't what you want here
[-4,-inf) and (4, +inf)
ℝαμOmeganato5
after this its complete 😭?
for inequality notation, you'd write
$$x\leq -4 \vee x> 4$$
ℝαμOmeganato5
yes
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How to get that; x ≤ -4?
i mean i know why it should be; x ≤ -4
but our teacher based his on an equation like
x-4≥0
x≥4
though cuz of that he also got x≥-4
i wanna know if there are any other ways to get x≤-4 by means of equation
annoying casework
U means union
yez
that is unfortunate
though cuz of that he also got x≥-4
how did he get that?
(because that'd be wrong here)
ts what im confused too
do you have a pic of their work
lemme send what we copied on the board
yes i do
this honestly just confuses me cuz it contradicts😭
yeh, that middle part with 2x >= x-4 is dodgy,
ignore/erase it
intentions of the bottom right chunk is a little unclear too
im taking notes on my personal notes so its fine
In case our teacher insisted that he is correct then at least when he checked the notebooks I'll still be fine w the grades
intentions of the bottom right chunk is a little unclear too
ok, that identifies when x-4 and x+4 are positive (for the sign table)
the sign table is missing
x+4
x-4
on the left column
oh wait lemme draw the graph that our teacher drew as well
i forgot to copy it bcs it did contradict with our graph
Which kind of implies that
[-4,inf) U (4,inf)
hence the x≥-4
oh so thats what it was
Are there any methods?
wdym
like we would use reasoning to identify the interval notation, like theres no specific methods by equation like ex.
"If x+4≥0 then
x≥-4, thus the lowest interval is greater than -4"
yes
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Can anyone help number 7
2^x -3^y = 5
Solution I got (3,1) (5,3) for pair of (x,y)
I couldn't prove that there will be no solution other than that
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6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
Show your work, and if possible, explain where you are stuck.
i was thinking that you could maybe consider both sides of the equation modulo some specific small power of 2 or 3
but i haven't been able to find one that works
mod 6 gives x must be odd
maybe that is helpful
LTE might also work its often used in questions like these ones
X and y must be odd
I mean x and y are different
why should y be odd 
do uk what is LTE btw?
yeah
Like that ?
Since x is odd
Substituting x = 2k+1
Then mod 4
ah okay thx
modulo a small number cant work because there are some solutions and modulo cant tell the difference between those and possibly bigger numbers
ah okay
then what should i try here
dunno
okay so i found a solution via approach0
okay
should i hint u or should i send the solution
what is approach0
its a platform to search for solutions to math problems
ur problem has been posted in an AOPS thread
and i found a solution in that thread
lifting the exponent lemma
yeah
yeah that thread contains a solution
approach0 helped me find that thread
anyhow, back to this
Give me the general idea / hint so I can understand it by my self
well assume that x>5, y>3
then write 5 as 32-27, factorize
then use the fact that x and y are odd to note that x-5 and y-3 are even
then use LTE, then FLT and some computations
and then u arrive at a contradiction for the value of v_3((x-5)/2)
i get 32(2^(x-5)-1) = 27(3^(y-3)-1)
the what should i do next
*y-3
mb
from here, rewrite your expression as 32(4^a-1)=27(9^b-1)
now try to use LTE to find v_3(a)
alr
so just v3(3)+v3(a)+v3(32) = v3(27)+v3(8)+v3(b)
yeah ...
theres a much better way to simplify the rhs
LHS is correct
how
and also
3 must divide x-y for this to work
but in our case x-y=8
yep
so u cant do what u did on the RHS
yes lol
its okay bro
mhm now go back to my list of hints
i want to say that b is not a multiply of 3
b wont matter trust me
alr
now what can you exactly apply fermats little theorem on
i suppose that we plu a = 9b here
plug *
nope thats wasting time 😐
u saw that 9|a and u need to apply FLT on something
which term do you think it should be
couldnt see it
well u need to do the following
4^a = 2^2a = (2^18)^(a/9) = 1 mod 19 by FLT
reason?
- you just derived that 9|a, so clearly you should do something with the term containing 4^a
- since 9|a, a/9 is an integer which is the motivation for the 2^2a = (2^18)^(a/9) manipulation (remembering u need a power to apply FLT)
from here, 19 | 4^a - 1 which means 19|9^b-1
now its a bunch of computations
do whatever the fuck this is
i have no clue how you're supposed to think of this step
this obtained through a computation my ahh
fr
i mean this proof is somewhat edible
i mean is this problem imo level or just hard national level
theres also something called hensels lemma which maybe usable?
my original intuition is exactly like this
no clue
but
i see
i am stumped in the case that (3^(c-3)-1)=(2^(a-5)-1)
but the more i think
what i was thinking back then bruhh
isnt that similar to what we derived in the computation soln 
also formally proving this intuition is not easy
the only problem that i found is that (2^(a-5)-1) = 27b and (3^(c-3)-1)=32b
but
they couldnt be posibly have the same factor right
or their gcd is 1
prove it 
err b is odd ?
b is odd right right
m not telling m asking
yeah
why r u agreeing 💀
i am very clueless about what you're doing rn
im also clue less
haow can the author decide to only work on 3^(c-3) -1 = 32
like
why would i know 😭
i dont understand that solution xd
i posted it to see if u could make sense of it
the only part of it where i couldnt understand
https://math.stackexchange.com/questions/1781722/prove-that-2x-3-cdot-9m5-has-no-positive-integer-solutions-for-m-geq-2?
heres some more mad math solutions to your question btw
https://math.stackexchange.com/questions/3256556/solve-for-integer-m-n-2m-3n-5
this ones actually good
u need to do some order computation when it comes to exp diophantine
but this is much better imo
MY GOD
i found it
yeah as i assume
they both are coprime
(2^(a-5) -1), (3^(c-3)-1)
i mean diffrent proof diffrent a and c
write your entire proof in 1 message
so that i can understand it
(please
)
ill try to prove that 2^a... part is co prime with 3^c... part
since you can digest all else before it
oh
2^a ... part = 27b
3^c... part = 32b
(why?)
since 32(2^a..) = 27(3^c....)
hence 2^a...... = 27b
3^c.... = 32b
i aint writing all at
then we know that 2^a..... is odd
then b must be odd
???
you know what
this prove is flawed
proof*
even i cant write proeprly 😭
cooked
r u self prepping?
yeah
thats tough
i mean
check this.
whats bad about the first proof 😭
the second proof is hell no
well this proof is good
not the 757
the first proof
yeah
but it seems the 2nd proof generalizes better
but ofc u cant use it in an olympiad
then what it is use for
solving for solvings sake, i guess
i mean
this question shoulndt be in any olympiad right ??

i think they've been asked before
man
i could be wrong though u'll have to do some hunting yourself
not every one is as tough or involved as this one
some are easy enough that u can argue by simply properties of primitive roots and stuff
https://math.stackexchange.com/questions/1941354/elementary-solution-of-exponential-diophantine-equation-2x-3y-7
for example this
yeah
what i meant to say is dont be sad, a question like this in an oly is unlikely to be as involved
because olympiads usually give problems that require u to think more than crunch numbers
yeah i understand
if ur done, coose it!
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f(x)=(x+a)(x+b), a and b are positive constants, f(-21)>0 and f(-15)>0 and f(-18)<0, what could be a+b
What step are you on?
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2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
(Is this a multiple choice question?)
i get that x=-21, -15 are outside the roots and -18 are inside the interval of roots so i got -21<-a<-18<-b<-15 or -21<-b<-18<-a<-15 but im kinda stuck from here
free response
so like i can enter any value
i solved it
.close
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@stark wedge sorry i just noticed that you have crossed my interpretation of this expression. can you please tell me what the correct conclusion would be?
Referance (this was my statement you crossed) : "so basically for even degree polynomials, its a_(n-k)/a_n (without the negative)"
(-1)^k will still be there
regardless if n is even or not
the product of all roots [which means k=n] is (-1)^n a_0/a_n, and in that case for n even the (-1)^n will become 1 and disappear
but since this was a quintic we were talking about, it would be odd, so the (-1) remains right?
yes (-1)^5 = -1
okay now i understand that term in your answer
(-1)(-2)(-3)(-4)(-5) + 6 = -120+6=-114 and then you multiply that by -1 for an answer of +114
can you give me a couple scenarios to make that expression in? so i know i have it down correctly this time
hmm sure ig
Let f and g be defined as follows:
- f(x) = x^7 - 4x^6 - 2x^5 + 60x^4 - 9x^3 + x^2 + 28x - 40.
- g(x) = 5x^3 + 8x^2 + 50x - 210.
Find the sums of the following:
a) roots of f taken 3 at a time
b) roots of g taken 2 at a time
c) roots of fg taken 1 at a time (ie just the sum of the roots)
@midnight pier Has your question been resolved?
incorrect! but show your work.
(sorry for the delays on my end -- i am with family rn and might not respond immediately)
wow still:((
no worries, more than willing to wait to receive a response
a and b are correct btw, only your c is wrong
I mostly just reasoned that the highest degree term here would be x^10 (theres only one combination of terms whose product results to that term: x^7 and 5x^3, so the a_10 (a_n) would be 5.
and i need product of tersm one at a time, k=1. a_9 (is the coefficient of the term x^9: which also happens to have one way: -4x^6 * 5x^3 : so a_9 is -20.
(-1)^1 a_9/a_10 = -(-20)/5 = 4
ohhh theres two ways
x^7 and x^2
a_9 = 8 - 20 = -12
but also you don't need to work out fg actually
it's just sum of roots of f + sum of roots of g that i want!
4 + (-8/5)
that's all
oh wait they'll all still have all those factors. so the multiplied polynomial will still have all those roots
is that a valid way of reasoning?
it's not just valid, it's exactly what i wanted from you.
or like
the recommended route
this reasoning would also work for the product of all the roots too
but not the other cases, right?
well actually would you like a more complicated general problem
where i do things like product of roots taken 2 at a time. because it would miss terms
yes please
right
gimme some time
let $f$ and $g$ be monic polynomials of degree $m$ and $n$ respectively, i.e.
\begin{gather*}
f(x)=x^m + a x^{m-1} + bx^{m-2} + \dots, \ g(x) = x^n + p x^{n-1} + q x^{n-2} + \dots
\end{gather*}
and let $h(x)=f(x)g(x)$.
without expanding $h(x)$, work out the sum of products of its roots taken two at a time, in terms of $a$, $b$, $p$ and $q$.
Ann
[you won't need any coefficients aside from the ones named!]
Leading coefficient is 1
correct

thank you soooo much for all your help:)
have a nice day:))
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<@&268886789983436800>, I think this counts as advertising?
uhh, is this not allowed?
I'm afraid we don't allow surveys like this. If you'd like to appeal that you should ask @feral pebble
I'm going to remove your poll now, apologies.
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@ruby sleet hey im back can you please teach me what you were teaching me yesterday sorry for the ping
for the table
@grave kernel Has your question been resolved?
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can someone explain to me why shifting the negative exponents from the denominator to the numerator works? I understand dropping the n^-2 to the denominator, because n^-2 is just 1/n^2, but i dont understand how m^-4 and n^-3 shifted to the numerator and became m^4n^3
$\frac{1}{\frac{1}{x}} = x$
artemetra
so basically this
also there is a typo here, there's one m missing
indeed
yup
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!status
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
Substituting u = 1 + sin(x) might be a good start
2
or try v = sqrt(u) and then partial fractions
i think its better way
Yep i've gotten onto the last part now
its classic integal
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How many months would this take to finish?
Not a math question. Please ask in #study-discussion
more than 6 weeks lol
The textbook is a maths textbook. Wouldn’t that qualify as a math textbook?
My bad if it doesn’t
help channels are for specific math problems
Oh alright
youre being redirected to a channel where your question is more appropriate
.close
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how to do this integral
ye
my first step would be to go to integral-calculator.net for advice
uh in seriousness though
let us try u-sub=(e^x+x+1)^2
we may have something related to the derivative in the numerator? (im not sure yet need to see myself)
uhh du=2(e^x+x+1)(e^x+1)
ohh wait
here
i give you related integral
Calculate $\int\frac{(e^x+x+1)^2-(x^2+x)}{(e^x+x+1)^2}\mathrm{d}x$
Arnavutköy
judging by the structure this was the result of some sort of quotient rule application
still
[ \int \frac{x^2}{(e^x + x + 1)^2} \dd{x} + \int \frac{e^x + x + 1}{(e^x + x + 1)^2} \dd{x} - \int \frac{e^x + 1}{(e^x + x + 1)^2} \dd{x} ]
doesnt work kinda
From this observation, it is just a matter of finding the right ax+b that gives you a useful derivative when you divide by e^x + x + 1 and do the quotient rule.
@midnight pier try integrating the first integral by parts
I suspect it will cancel out with the second one
or vice versa
oh alr
The third integral can be done with a substitution
maison
second and third ar easy
the second one by itself is probably non elementary
but what should be hte first function adn the second funtion for by parts
of the first one
how do i see these kinda things
take the second integral and differentiate 1/(e^x + x + 1) and integrate 1 (IBP)
like hwo do i check if i can integrate something or not
it should cancel out with the first hopefully
uh i am looking at the solution at integral-calculator.net and i can assure you that I would have never come up with this nor half of the people in the mit integration bee
hwo to integrate the first
it's a bit of an advanced technique with IBP
we're not going to integrate it
do you want to know what to rewrite it as
leave the first term
work on the second one
integrate 1 and differentiate 1/(e^x + x + 1)
Its a rational function of x's and e^x's without any weird nth roots or infinite sums. You are not giving people on an MIT Integration Bee enough credit.
ok
Even if this turned into a messy integral involving a bunch if dilogarithms it would not be out of reach of a group like that
lol
half an hour? this is doable in less, which is expected of integral problems
it can be done quick
okay now that i certainly disagree with
the approach you suggested is not even correct
on my JEE shift there was a similar problem except the reverse-IBP twice
it doesn't work?
this? no
bruh i just asked somebody ranked top 10 in all india in jee and they were stuck
This is also a jee question
it just comes down to testing things
hopefully not mains
not mains
wait is the answer multiple choice?
wait just combine it now
you can factor the x out
and reduce the power in the denom
essentially you only get this through guess and check in jee exam format
also idt that should be a - sign right
you get a - from the IBP and one from the derivative
so it becomes a +
you can notice i.e. $\frac{\mathrm{d}}{\mathrm{d}x} \frac{x}{D} = \frac{(1 - x)e^x + 1}{D^2}$, $\frac{\mathrm{d}}{\mathrm{d}x} \frac{1}{D} = -\frac{e^x + 1}{D^2}$
Mqnic_
,rotate
from here, you find $\frac{x^2 + x}{D^2} = (x + 1)\frac{\mathrm{d}}{\mathrm{d}x}\frac{x}{D} + (1 - x^2)\frac{\mathrm{d}}{\mathrm{d}x}\frac{1}{D}$
Mqnic_
and now you integrate by parts
it shouldn't be a - sign
you are done
It would be
I mean by parts give minus sign for the second term
and the derivative gives you another one
dude isn’t even reading manics messages
i am
probably multiplying with e^-x
one way is x = D - e^x - 1

which gives you the answer essentially immediately
ah yeah that works better
Yes
Thanks guys
Ik I am disturbing but can I ask another one
like i was trying asinx+bsinx property but still not getting the correct answer
i tried reverse engineering also by quotient rule
if this is what disturbing is i want to be disturbed
thx 😁
[ \int \frac{\tan^2 u}{(\sin u \sin \tan u + \cos u \cos \tan u)^2} \dd{u} ]
maison
u substituted x as tant
yes
I guess it wasn't a crazy idea after all
I've seen the xsin(x) + cos(x) structure in an integration bee before and I used the same technique
should nt there be a cos^2x in the denominator
multiply it inside
that's how you get this
in the denominator use the cos(A - B) formula
and rewrite the top using the pythagorean identity
oh
you probably see what can be done now
also there should be a ^2 over the cos (t - tan t)
maison
👀
not just tan t
yes
because the derivative is on top
But like how did u thought so much out of the box
I would have never thought in this manner
you'll get there with practice
integration was my favourite chapter in all of JEE i had a bit of an obsession
good luck lol
I made all my classmates and my teacher to sign a petition to remove integrals chapter from the syllabus
On our blackboard
Lol
I love it
I hate chem tho
Other than physical chem
hey @maison canu recommend me some great integration books
i need some guidance in it
i am currentyl doing modules and cengage sometimes
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is there some algorithm to follow so i can remember the 20 something integrals formulas? for derivatives it's kind of easy, even with composed functions, but for integrals it just looks random to me. i'm attepmting to learn them on my own during summer break.
wdym 20 something integral formulas
Just practice questions
the easy integrals are just reverse of basic derivatives
Also some formulas have same things but just a few changes which can be easily remembered
unlike for derivatives, there isn't a general algorithm that works for all integrals
and then its just u-sub and ibp
risch cough cough
-# technically there sort of is one but it's like 100 pages
Integral of tan is ln |cos| and ln |sec|
-ln|cosx|
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does someone mind helping me find out why the answer is B here? i guessed it
they're asking the y coordinate of B, which is the maximum value of the function
have you dy/dx yet?
the maximum of acosx + bsinx is root(a^2 + b^2)
yeah that works as well
if you don't get this i suggest you to do this first
set it equal to 0
then solve
then test if it’s a max or min using second diff or sign table
then u get 2 -3tanx right
if u divide everything by cos
yes
that'll be your y value
but make sure you sub back into the original equation
great
oh it’s the same
yea
there ya go
but use this
max point?
what you've done is a troubling way
whats the proof for this
or just type the formula out on google
you should get plenty of explanations
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eww jets nose pihh eww
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sinx (x in radians) = sinx (x in degrees)
What's the value of x (x isn't equal to 0)
convert the angles to either (rad to deg or the reverse)
so sin(xpi/180) = sinx right?
so your right x is in radians ?
Radians
Then solve for x in the equation
$$\frac{x\pi}{180}=x+2k\pi$$
Sherif Player
Where k is an integer
So x = 2kπ ((π/180) - 1) ?
Actually
$$\pi x = 180x+360k\pi$$
$$\pi x - 180x = 360k\pi$$
$$x(\pi-180)=360k\pi$$
$$x=\frac{360k\pi}{\pi-180}$$
Sherif Player
Oh thank you, trigonometry is confusing but i understood it
Do you understand why did we solve for that specific equation?
Not actually
For any trig function in the units of radians
f(x) = f(x+2kπ)
like
sin(x) = sin(x+2kπ)
And so on
Because 2π resembles a full revolution
So if we revolved the angle around k full revolutions it would still remain the same
Do you understand now?
There are actually more solutions to the system of sin because sin has another property which is
-sin(x) = sin(-x)
Which would be a bit harder to solve
Yeah, i understood it but i have a question. Is it because 2pi is period of sinx?
Yes
But general solution is 360kpi / (pi-180) right? When k is an integer
Yeah that's a general solution
What's this app?
Not at all, thanks for your help
!done
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how do we draw this again?
for k = 1 we get y = +-3z whic hi get the 2 lines
but the parabolas how do we draw those
anyone know how and why?
examine y = 0 and examine z = 0
yep so those are the peaks of those hyperbolas
i did that but what does that gotta do with anything
but how do i know to draw parabolas
at thsoe points
is what im asking
in the zy plane yea where x = k
but yeah you know they're hyperbolas because they follow the form $az^2 - by^2 = 1$
not haylee
hm ok so this is just memorization
also what the fuck does the k = 1 thing have to do with the full hyperparabola
kinda yeah. it's a common conic section
hyperbola
it's a degenerate hyperbola
these are conic sections, have you seen this before?
3 is a hyperbola
1 is a parabola and 2 is an ellipse
the crossed lines are what happens when the plane in 3 crosses the centre point
it's degenerate when it's of the form $az^2 - by^2 = 0$
not haylee
so by setting k = 1 the right side becomes 0 and you get the degenerate case
so is this the math rage bait
?
anyways
so for the y=k i understand this right
we draw circles
but im confused about the x=k
how to incorporate what we drew on that 2d plane here
well the crossed lines is what happens when k = 1
yeah i dont understand where to draw these
or the sides
oh i see what you mean
imagine you have that hyperboloid (boomerang looking thing)
and you look at it from the side so kinda like you've drawn indeed yea
just the 2 crosses left
well the shape you've drawn is for k = 0
it'll look different for k = 1
in particular its waist will be fully snatched and drawn in to a point
yes, most of the time it looks like pictured
where is the crosses incorporated here in the pic
oh hang on
this looks nothing like my graph answer what?? in the zy plane
okay i see, i think the crossed lines happen when the plane youre looking at is tangent to the inner waist of the hyperbola
if this is where you take your projection
you can see the crossed lines
(i got this by plotting x = 1 and hitting "extend to 3d")
what parabolas
after playing with it in the graph view, do you see how the hyperbola gets drawn tighter until it becomes a pair of crossed lines?
yep
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Hey everyone
hello
How is this a "legal" move:
Can someone explain please?
[ \sqrt{x^2} = |x|]
k
Yes ik
Then what? 😅
But |x|≠-x
because when it goes to negative infinity, it's negative
↑
It's the definition of |x| ...
Do u mean:
[ |x| = \begin{cases} x & x \geq 0\
-x & x< 0
\end{cases}]
Yeah I corrected it
If $a<0$ then $|a|=-a$ isn't it
Alexis_Fx
Oh wait
k
Yes
That's true
Oh I get it
If x is negative then the absolute value is -x
Makes sense
Ok sorry haha
Thank you guys
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dont undersand
show the full question.
ok, so then
did you do part a?
