#help-10
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<@&286206848099549185>
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o oops im new
it’s 1
buddy ur arguing with someone in calculus 3
or not
calc has nothing to do with
uhh number theory or alg
i love you
no one saw that bro
the uno reverse
This ain't calculus
halp
ok if this ain’t calculus then ur real analysis
👁️
i’m math 55
im math 69
the hardest class at harvard
hardest class at clown school
I don't remember this stuff. You need somebody who's recently done Discreet or maybe Combinatorics
wait heres the solution
i jut need someone
to decipher it
I can't do that, there's too much unspoken
are you a discrete function or continuous
But I recognize the series as being used to solve problems in Combinatorics
yeah its supposed to be a generating function
just no idea how he factored it
<@&286206848099549185>
There's the words
Generating functions
wow
halp
hi
Hi
help
@west delta Has your question been resolved?
@west delta Has your question been resolved?
@west delta Has your question been resolved?
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How would you get f(-3^(1/2))
f is just made up of straight lines
Find h' with product rule first
@uncut parcel Has your question been resolved?
<@&286206848099549185>
Look at the graph
f(x) is a line from x <0
So if you find the slope you can find f(-sqrt3)
Do you mean *1/2 not ^1/2
ok
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I need to prove this statemen
I tried to induct on number of edges. Denoted with n in the proof
@frosty brook Has your question been resolved?
@frosty brook Has your question been resolved?
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I'm currently training for a math competition, and in several practise questions i found that it is required to be able to isolate a variable in a two variable quadratic equation (usually not factorable). One such example that I need help with understanding: Find all integer solutions to $x+y=x^2-xy+y^2$. The solution involved isolating y, and I do not know how to do so. Any help is appreciated.
everything_addict
isn't the quadratic just:
x^2 - (y+1)x + (y^2-y) = 0
those questions are written with the intention that you should not be able to isolate any of the variables, you solve them with other ways such as finding inequalities or in your quadratic finding the roots and setting them equal to zero to break it into smaller equations
@devout yarrow Has your question been resolved?
The solution in the book itself finds y in terms of x
could you show the equation the book has for y in terms of x
everything_addict
here
yeah thats the same as finding the roots of the quadratic, in this case the quadratic is $y^2 + y(-x-1) - x + x^2 = 0$. Apply the quadratic formula and you will get the same equation.
nova
ok
Now the term under the square root must be a perfect square in order for y to be an integer
ill try manipulating to get that form
yep
its easy from there
thanks for ur help
i managed to manupulate it to a typical quadratic
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Two mutually directed chords are drawn from one point of the circumference
how to draw this
@plain sparrow Has your question been resolved?
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i need help
!da2a
No need to ask “Can I ask…?” or “Does anyone know about…?”—it’s faster for everyone if you just ask your question! See https://dontasktoask.com/
hi
hi
can u dm me
no
i need personl help
Just post your question here.
eyebrow raised

What do you know about a rhombus.
What do you know about the lengths of the four sides?
ig i gotta make triangel ccongurent
right
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Does anyone know how to answer these questions?
assuming those are functions, g/f seems to represent g(x)/f(x) for x in the intersection of their domains
It does seem like you do have to intersect the domains, so do that first
I never encountered that being a thing, but I guess it is here
and then you can answer for each point x in the domain what f(x)/f(x) is
and that way you have a new function
huh
I didn't get it
are you familiar with the concept of functions?
so if you think of f and g as functions, you can say stuff like f(3) = 2 and g(3) = 8
yeah
and then we define g/f (a new function) as g(x)/f(x)
but we cant really allow x for which we have no outputs from g(x) or f(x)
so we restrict x to be in their common domain
what do you mean by "allow x"
how
how did they get this
same here
I don't get how to answer these questions
oh so you didn't understand the + one too
yes
might help to read on "function composition"
wait thats not the right term i think
one min
I know how to find the composite of functions if they ask for (f(gx)) or g(f(x)
sorry, composition was the wrong word
when they say f + g it's just the sum of their individual outputs
Sum and difference and product and quotient of function you mean
yes
oh wait lemme try
Yah no Idk
suppose I want to find (f+g)(2)
this is f(2) + g(2)
by definition
can you find that in the second question?
f(2)=-1
g(2)=-3
f(2)+g(2) = (-1)+(-3) = -4
thats correct
ohhh
so now we add (2, -4) to our set
it's the same thing, except you do g(x)/f(x)
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could anyone help me prove this
uhh could u explain i am kinda confused
sure
do you recall any theorem that relate the ? with theta?
uhh no
oh ok,do you recall
angle at centre=2×angle at circumference
it's an isoceles triangle
now that you notice that theta/2 you can try and notice which tan(theta/2) related to
specifically which right-angled triangle
do tell if you want to get the triangle highlighted
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How do I solve this?
can you express 27sqrt7 as the product of two terms?
yes
log(base 3) 27 + log(base 3) sqrt7
it'll be 3 +
idk how to get x/2
ohh
I got it
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<@&268886789983436800>
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could someone help me solve it i got a quadratic equation 11x²-78x-120=0 which doesn't solve to whole numbers
show your work
maybe you made some kind of arithmetic error somewhere
also what are your pronouns?
anything i don't mind
it's kinda messy u won't understand
ok you can take off all pronoun roles except "any pronouns" for future ref
then rewrite it to make it not messy
otherwise it is impossible to diagnose where your error came from
alright is okay if i close the req now and reopen it in 10mins with same question or will this channel stay like this ?
you'll get pinged after some time, press ❌ on the bot prompt to keep the channel open.
then ping me once you've got your work so i can look at it.
oh alright thanks
i reproduced the thing and got almost the same equation as you though, except my x coefficient is different. mine doesn't seem to have any integer solutions either though.
although nobody said i didn't fuck up either
hang on
nevermind, my equation does have integer solutions (hopefully).
@daring cairn Has your question been resolved?
on redoing it i have noticed i made a mistake
is the equation 11x²-98x-120=0
matches mine now
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guys
f(x) 9x^2-2x and g(x) = e^8x
for f(x) i did 3 derivatives
and for g(x) i did 3 integrals
in the final i got
this
but when i check an example, it wants an answer like this:
but i couldnt get the last part
this one is from a differnet question
differnet*
different*
Answer like that? Wdym?
I can't get it this way
The first term, ig in the brackets it should be (9x²-2x) instead
yes
okay i got it this way
but im not sure is it correct or no
thank you
.close
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Lg100-lg0.1
what is lg?
Uhh hello?
log most likely
log
ok
the base though? couldnt tell u
yeah, 10^2 = 100 and 0.1 = 10^-1
base don’t matter
not 10^-2
ah so 3?
log 1000
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3 log 10
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angular velocity is radians/time in seconds yes
go through the definitions and information over time
you know the length, so you can calculate the area of its circle
then you can calculate how frequently it goes through that circle
Yeah u can calculate the amount of radians swept in the 8s using the area given and the area of the circle
then just divide by 8 to get rad/s
because your 50 square meter area thats been swept out is the area multiplied by some amount of radians
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what does this mean ??
ik it's Laplacian but idk what this is :
Just a vector
problems with old books: old notation
prof is still using it till this day : (
.close
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no that’s a logarithm
probably functioned in with a square notation
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im having trouble with the rad/min
imperial system… yikes
Basically the 65 miles per hour is your linear velocity
12 inches is your radius
do the conversions needed
then plug them into the formula
*15
mb im dyslexic
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The generating cone is inclined to the plane of the base at an angle ү. The distance from the top of the cone to the center of the sphere inscribed in it is equal to d. Determine the area of the lateral surface of the cone.
I think it looks something like this
so S= piRl
I need to find CB
and radius
idk how do it
@vernal void Has your question been resolved?
<@&286206848099549185>
what DO you know ?
.
this
and this
it doesn't say if you know the value of anything
are you trolling or do you actually need help?
really need help
ok
I just gave an example that your question is not very precise
do you know the value of mAB?
this is the only information that the question gives?
yes
m?
mesure of point A to point B = mAB
this is the diameter of the base
!original:
Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.
it's in Ukrainian, can you translate it?
yes, mostly with my phone
what grade are you in, cause i'm going to use university level stuff
not this?
you are right my formula add the base under witch is out of the question
I think we need to use trigonometric formulas here
so we have a circle inscribed in a cone and not a cone in a circle
oh
sry i blind
but I don’t quite understand how this will help us
i showed you how to put a circle inside a triangle, all you have to do is the process inversed
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mj
also a valid solution?
why not?
they're not completely identical but they have the same properties listed in the question
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The question is a+b+c+d=4. Prove abc+bcd+cda+dab<=4
But I worked out abc+bcd+cda+dab<4, can someone help pointing out what is wrong please, or tell me the correct way to solve this problem.
My approach is as followed:
4>=(a+d)(b+c)
16>=(a+d)(b+c)(a+b+c+d)
16>=(2×sqrt(ad)×(b+c)+2×sqrt(bc)×(a+d))(2(sqrt(ad)+sqrt(bc)))
4(abc+bcd+cda+dab+sqrt(abcd)×(a+b+c+d) 4-sqrt(abcd)×(a+b+c+d)>= abc+bcd+cda+dab
We can easily prove that 0<sqrt(abcd)<=1 so
4<abc+bcd+cda+dab
Which is wrong because 4 can equal abc+bcd+cda+dab.
try using (a+b+c+d)^3
Can you explain more please?
🫎Mοοsey🫎
You wrote a^2+b^2+c^2+d^2>=4 before, isn't it correct?
i was just overthinking, yeah its correct
assume all but one have magnitude less than one (only case where squaring gets smaller)
Yeah I mean I can prove it, you dont need to go further here, please continue with a^2+b^2+c^2+d^2>=4
ah wait i was thinking wrong :I
So can you point out where my proof is wrong? Maybe we can work from there?
@molten fractal Has your question been resolved?
<@&286206848099549185>
OK I might not be able to help you but first format it in latex
Do you know a program that can do it automatically?
Nah
.close
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The question is a+b+c+d=4; a,b,c,d are positive real number. Prove abc+bcd+cda+dab<=4
But I worked out abc+bcd+cda+dab<4, can someone help pointing out what is wrong please, or tell me the correct way to solve this problem.
I worked out
4<abc+bcd+cda+dab
Which is wrong because 4 can equal abc+bcd+cda+dab.
,rccw
Well there's a simple solution by changing the unknown
a=1+i+j+k
b=1-i
c=1-j
d=1-k
The inequality equals when i=j=k=0 but it's not the intended solution (the author explicitly told to use cauchy, cauchy might refers to the simple case, AM-GM, in my country)
thank you
non equal cauchy
Can you explain in details please?
i want to ask you about the question which used inequality cauchy
i can't understand cauchy
So do you mean my solution is too messy or is there a line you don't understand?
I can't understand 4 >= abc +bcd +cda+ dab
Well it's what I'm trying to prove
Is there anythin else?
I'm afraid to bother you while you think
<@&286206848099549185>
@molten fractal Has your question been resolved?
You should use AM - GM inequality
firstly , apply it to a , b , c , d
and you will get a relation
and then apply it to abc, bcd , cda, dab
$$ \text{Given , a + b + c + d = 4} $$
🎀 𝒫𝒶𝓃𝒾𝒸 🎀
Please continue sir
Using AM - GM inequality
$$ \frac{a + b + c + d}{4} \geq \sqrt[4]{abcd} $$
🎀 𝒫𝒶𝓃𝒾𝒸 🎀
But we know that a + b + c + d = 4. So,
$$ 1 \geq \sqrt[4]{abcd} $$
$$ 1 \geq abcd $$
🎀 𝒫𝒶𝓃𝒾𝒸 🎀
Now , we use the AM GM inequality on abc , bcd, cda , dab
$$ \frac{abc + bcd + cda + dab}{4} \geq \sqrt[4]{abc \cdot bcd \cdot cda \cdot dab} $$
🎀 𝒫𝒶𝓃𝒾𝒸 🎀
Welcome
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How many two-digit numbers can Ahmet write on the blackboard such that the difference of any two of them is not a number consisting of two equal digits?
Ahmet is a name
so in other words: how many 2-digit numbers can we write on the board so that no two of them differ by a multiple of 11
do you know modular arithmetic?
if you do then my rephrasing of your question trivializes it
i know a little bit about it
you want your numbers to not be congruent to each other modulo 11.
or in other words you want them all to have different remainders mod 11.
how many remainders are possible when dividing by 11?
10
1,2,3,4,5,6,7,8,9,10
you forgot one
0 ?
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$\frac{\partial f}{\partial x} \cdot \frac{\dd x}{\dd t}$
Adam Chebil
can i simplify with partial x and dx ??
What do you think?
f_x dx/dt + f_y dy/dt can't really be simplified much further can it?
also differentiate* not derive
Simplify? I mean you would just find dx/dt and times it by del f/ del d
they didn't use del operator here ?
I meant partial
i don't understand why we multiply by dx/dt ?
also shouldn't be written as partial f / partial t ??
x changes as t changes
same with y
so we account for that (chain rule essentially)
no since f "depends" on x and y, and both x and y "depend" on t
also i see some other person was covering the exact same thing lol, maybe their notes will be helpful to you #help-7|zen1thxyz message
i don't see how we applied chain rule here : (
let's make it a bit simpler and consider f(x)
1 variable
and we are looking for $\frac{df}{dt}$
artemetra
where $x=x(t)$ - some function that outputs $x$ given $t$
artemetra
artemetra
artemetra
we have composition of function hence chain rule
therefore, we also need to multiply by the derivative of x w.r.t t
hence, $\frac{df}{dt} = \frac{df}{dx}\frac{dx}{dt}$
artemetra
you might also want to take a look at related rates, a very similar topic
@fierce vale does that make some sense?
@fierce vale Has your question been resolved?
why df/dt = df/dx here ?
it's not
i put a * there in front
it's more of like the process yk
i think that image was extra, sorry
start with this
here we differentiate the inside function which x(t) with respect to t
but why did we differentiate the outside function f with respect to x and not t ??
that's what we are trying to find
df/dt is what we are looking for
shouldn't this be equal to : $x'(t)\cdot f'(x(t))$
Adam Chebil
artemetra
$f'(x(t)) = \frac{df}{dx}$
artemetra
yeah this is what i don't understand
f'(x(t)) = df/ dt ? no?
how do i know which variable i put ?
but $\frac{df}{dx} = f'(x(t))$ because it's the derivative of f as x changes, not t
artemetra
wait f here is a single variable function ??
yes
oh ok
^
my problem is with multivariable fcts
multivariable is the same just done twice essentially
do i write df/dx or df/dy ??
$f(x,y) = f(x(t), y(t))$
artemetra
wdym?
$\frac{\dd f(x,y)}{\dd t}=x'(t)\frac{\dd f(x,y)}{\dd x}+y'(t)\frac{\dd f(x,y)}{\dd y}$ ?
how do i do this ?
df/dt
Adam Chebil
i think i understand it now
can u explain when do should i write partial f or df ??
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am i missing something? question asked about the stationary points, why are they doing the 2nd derivative? as far as im concerned f'(x) = 0 are the stationary points
part b btw
i got x = 3 as a stationary point but i dont get why they did the 2nd derivative and found the minimum, someone explain if im missing something pelase
It's another method to classify stationary points
@timid silo Has your question been resolved?
how
also pls ping when u reply cuz i didnt see ur first message
anyways whats another method of classifying them
the 2nd derivative?
id understand if it was another method but its saying that the 2nd derivative has points yk
meaning i have to do both first derivative and second derivative to get the full grade
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I would like to clarify my logic.
Zero Velocity = The object is stationary.
In this position vs. time graph, "B" is the stationary object, while A moves away from point of origin and C returns to origin.
Therefore, the letter on the chat that corresponds to zero velocity would be B.
If I am not on the right track, please redirect..
Yeah with 0 velocity, the objects position doesnt change as it doesnt move
Objects stationary
B is at 0 velocity
@mint arrow Has your question been resolved?
yes C has a negative velocity
as its a straight line, velocity is constant
so C is where the velocity is constant towards the starting point
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hello
I made a mistake by clicking on the left-side in spyder, i can't go back to my codes lines 
I'm stuck, anyone can help me please
Hey umm, this is a math server. Please keep your questions limited to that subject.
There are many other servers that'll help you with your coding and ide stuffs.
P.S. I would've still helped if I would've known this, but I don't.
Try going to the server that would actually help you out
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my lecturer said that this is true
but I think I lost the explanation of such property
was there such property?
I'm new to integrals
the derivative of ln(x) is 1/x, here d(ln(x)) simply acts as the element/variable wrt which you're integrating
wrt?
with respect to
have you heard of integrating by change of variable?
uhh I think no
let me think this through
so
integral is basically f(x) is derivative of what
right?
[integral sign]1/x(dx)=ln(x)
ohhh
I see the tendency
Ohhh so it's because
or these have to be the same
yes?
does that mean that these have to be the same?
(1/x)(dx)
no, I can integrate for instance dx/tan(x)
this is basically just integration by substitution (or change of variable)
you basically define u=lnx
substitute it in the integral
and that eliminates 1/x
but yes the variable has to be the same
ohh
ohh
wait
so
if you understand integ by substitution itll be quite obvious what they did here
let me write this using paint
excuse my bad writing
but instead of actually replacing lnx by u
they just left it as it is
if we have it like that, we can use substitution
such so t=ln(x)
i mean you could replace ln x by t here mentally. but at this stage it isnt needed
but then why did this happen?
because the boundaries are originally in x1 and x2
so when you change the variable you have to adjust the boundaries accordingly
🤔
basically here you deifned t=lnx. and changed everything inside the integral to the variable t
but the boundaries also have to be changed since they were in x
oh, right
right
at this point tho it isnt really necessary to use substitution
you use substitution when whatever you are integrating is in the form of a function multiplied by its derivative
you dont need to try to figure out how integ by substitution works from scratch.
there is a lot of content on it online.
its the type of idea that really clicks when you solve a couple examples
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Someone help me solve this regularly without using the L’hopital’s rule
1 - 2sin^2(x) = 2cos^2(x) - 1 = (2cos^2(x) - sin(2x)) + (sin(2x) - 1) = (2cos^2(x) - sin(2x)) - (cos(x) - sin(x))^2
can you continue from here?
yes
I got 2 answers from doing it
first one is 1 and the second one is 0
Idk which one is correct
how did you get them?
is that in any way related to what i wrote above?
isn't it just the first step of the transformations i provided?
yes
how did you derive that?
the denominator is incorrect
there you only multiply the first term by 2
but it should be both
So its 2-2/2-1
no
can you solve it for me i will try to understand
it's a 0/0 indeterminate form
the tricky part is transforming the numerator
that I've done above: #help-10 message
then just split it into two fractions and reduce each separately
uhh
can u tell me the answer i will try to find solution to the answer
i dont really understand english math so its pretty difficult for me
there's no such thing as "english math"
math is math
did you understand these transformations?
each step involves some formulas
the second step is just adding and immediately subtracting sin(2x)
I see
we do this so that a part of the numerator exactly matches the denomirator
What about the next step
so we'll be able to reduce this part to 1
the last step is to transform sin(2x) - 1 into -(cos(x) - sin(x))^2
Is it trigonometry formula
you can derive it this way:
1 - sin(2x) = (sin^2(x) + cos^2(x)) - 2 sin(x) cos(x) = cos^2(x) - 2 cos(x) sin(x) + sin^2(x) = (cos(x) - sin(x))^2
we use the pythagorean identity and the double-angle formula for sine
which one?
the pythagorean identity is sin^2(x) + cos^2(x) = 1
phytagorean idenity
And double angle formula
do u memories all the formula or what
there are formulas for sin(2x), cos(2x) etc
e.g. here we use that sin(2x) = 2sin(x)cos(x)
in my country try we just memorize all of them
you seem to have used it already judging by your denominator transformations
but there are too many so i only memorize a few of them
do i dont really understand the formula
jut the frequently used ones (like these)
so if u transform it further its pretty hard to understand
well, from this point everything is reduced pretty fast
so did you understand this part?
What are the frequently used formula for cos/sin 2x and cos/sin x^2
I understand it now
there are actually just 3 main formulas that are used very often:
sin^2(x) + cos(^2x) = 1sin(2x) = 2 sin(x) cos(x)cos(2x) = sin^2(x) - cos^2(x)
by combining (1) and (3) you also getcos(2x) = 1 - 2sin^2(x) = 2cos^2(x) - 1
there also half-angle formulas (for sin(x/2), cos(x/2)) and formulas for things like sin(x + y), cos(x - y) etc
and many others but you don't see them too often
anyway, if you understand where they come from, you can always derive any of them even if you forget it
I keep forgetting the sin(nx) formula so I just derive it using complex numbers and de moivre's theorem
lmao
don't mean that one lol
Alright tysm
do you understand what to do next?
good, i assume you mean 1 - lim ...
also it should be sin(2x) in the denominator
What is 1 - lim ...
not sin(x)
1 minus what's on your picture
because of the other part of the numerator
not so fast
you have an error here
well, 2cos^2(x) - sin(2x) for x = pi/4 is still 0
so in this form it's still 0/0
there's one additional step missing
maybe you've already done it and just not mentioning it?
yea but there’s 1 minus the 0
wait
0/0 is not even a number
because both numerator and denominator are 0 for x = pi/4
is 2x1/2
can you see how you can reduce the fraction?
and why such reduction would be legal (i.e. why you don't divide by 0)
i dont really understand what u’re saying
can u write it down
thats what i meant “ english math “
do you what reduction is?
yes i know what reduction is
can you figure out how that can help you simplify the fraction?
it's not calculus, just basic algebra
do you see any common factors in numerator and denominator?
‘Cosx-sinx’ ?
idk actually
well, it would only be illegal if it could be equal to 0
the thing is though, it's only 0 when sin(x) = cos(x)
and as x approaches pi/4 it never actually gets to exactly pi/4
so sin(x) and cos(x) are always different
by a small bit?
yes
what about reducing by that?
wdym
using a^2 - b^2
i don't see a difference of squares anywhere here
why did you sugget cos x - sin x?
when i asked about common factors
cuz i see it both has it
numberator is the upper part and denomator is the bottom part right
yes
numerator, not numberator
and denominator, not denomator
but otherwise you got it
so its equals to 1-1
no
they only have a common factor of (cos x - sin x)
like 10 and 4 have a common factor of 2 but still not equal
the thing is idk how to devide the denominator by that expression
well you said it yourself that it is a common factor
to deduce that you'd need to factor the denominator (at least in your head) in the first place
still no
can you write the denominator for me such that it contains (cos x - sin x) as a factor?
2cosx ( cosx-sinx )
I know you've spent a long time on this problem going down this path for the last 2 hours (which works), but the clever trick for this kind of problem is to notice that a limit as x tends to pi/4 doesn't allow you to use a small angle approximation, nor does a substitution y = x-pi/4 make it easy to do so. So you use the substitution y = 2x-pi/2 which has y tend to zero as x tends to pi/4 and that immediately lets you simplify everything down into polynomials and calculate from there.
other than that you forgot about the 1 at the beginning
so now the problem is almost solved
you just substitute
there's no 0/0 anymore
I’ll try this method after i solved it this way
So this is the final aswer
Answer
yes
indonesia i guess?
Cambodia
Imma try this method
Is this how you do it
i use “t” instead of “y”
@willow dust Has your question been resolved?
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how’s this supposed to be done
!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
im at the lcm part
Can you send your work?
Your denominator doesn't seem to be right
expand (1+sin)^2
1+2sin+sin2
^^
cosy+sinycosy
ok how do i get 2sec
Write cos2 in terms of sin2
2+2sin is?
2* 1/cos is what?
2SEC
yes
THANK U SO MUCH
np
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I've been learning a lot about the Discrete Fourier Transform lately, and though I'd try to recreate something in Desmos. What I came up with ends up flagging the correct frequencies, but also flags a bunch of incorrect frequencies as well. I'd be really grateful if someone could take a look at my Desmos thing, and I'd appreciate some pointers on how to fix it.
https://www.desmos.com/calculator/iiyzjtws9r
Also, sorry this is a duplicate, but there was a misunderstanding with the original question that caused it to be buried
@distant wasp Has your question been resolved?
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i did the integrals over dxdydz