#help-38
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how would i come across to solve this
what have you tried
double angle identity?
no
you should be using the zero law, not dividing by -2x (-2x might be 0 and you can't divide by 0)
if 2 numbers multiply to make 0, then either of them must be 0
Yea but if i dont do that idk what to do
im a bit lost
ab = 0 => a = 0 or b = 0
so the hard part is finding x such that sin(x^2) = 0
Yea
so when is sin(Φ) = 0?
oh
YEP never heard of it
when Φ = 2nπ for some integral n, right?
just periodicity
🤔
so just set x² = 2nπ and solve for x
uh
draw the graph of sin
Actually every pi*n
yeah, right strike the 2
n being an integer
and i dont like it it looks scary
how scary can it be to take a square root
mhm
so you end up with all x such that $x = \pm \sqrt{n \pi}$ where $n \in \mathbb{Z}, n\ge 0$
(just make sure you don't take square roots of negative numbers)
\pm
YEA
$n \in \mathbb N$ assuming we're looking for real solutions
depends on where you live
??? England
lol
varies by author
from what i've seen in the US most authors include 0 i nthe natural numbers, while in Europe most authors exclude it
even if it doesn't include 0, you already identified that as a solution
oh my prof was talking about this yesterday
but there are exceptions on both side of the pond
i like $\mathbb Z^{\geq 0}$ for unambiguity
Bungo
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Does anyone here knows how to use GeoGebra for Parabola?
Like the app or website
For Parabola, as in, do what with the Parabola?
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The daily production cost (in lakh ₹) of manufacturing an electric device is p(x) = 7400-60x+15x^2 , where x is the number of electric devices produced per day and the daily transportation cost (in lakh ₹) of x number of electric devices is given by the slope of the function p(x) at point x.
A)How many electric devices should be produced per day to yield minimum production cost?
B) if the transportation cost of the electronic devices on a particular day is 30(in lakh₹),then find the number of transported electric devices.
I don't understand the question '-'
@vital saddle Has your question been resolved?
<@&286206848099549185>
You are given a function over cost of production
You are asked to find amount to product such that the cost is as low as possible
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I am having trouble understanding how the first two questions are solved using unit vector
I am stuck in the part on how exactly the problem is solved using tan
Usually you put the vector into the unit vector formula and solve like in #25.
But the ones using tan have different phrasing and i do not understand how to solve then.
@sage plover Has your question been resolved?
No
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<@&286206848099549185>
@sage plover Has your question been resolved?
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,rotate
n is a 5-digit number. That means it has a domain from 10000 to 99999.
Pick any number n in that domain and divide it by 100, what will the quotient and remainder be?
the last two digits?
thats the remainder right
anf the front three is the quotient?
do i just brute force all the possibilities then
It would be useful to brute force a few solutions that are divisible by 11, then try to generalize a solution based on your results.
is there another method?
Of course, and you are trying to figure that out.
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got a question
thanks
you should begin by posting your question
thanks
thanks
Yeah my fault
Anyways so on these 3 idk how I’m getting them wrong
There are other questions exactly like this but in CSC instead of SEC
There must be some rule for SEC that makes it different than csc
So if anyone knows plz help
<@&286206848099549185>
uh idk im just learning this stuff and my teacher is like sick or something so ive got no assistance in the last 2 weeks
I forgot the bottom
Secant is the peaks and crescents of cosine right?
At each peak and crescent a parabola looking graph occurs right?
yes
You plug and check here basically
wait so is that the same for cosecant to sine?
i really dont know much on this topic
Plug in 1/2 and see what you get
does sec of pi/2 exist?
yea
ight. we arent allowed to use calcs tho
like for my actual class
is sec on a calculator sin-1
if it is then it doesnt
sec on a calculator isn’t sin-1
then idk bruh
alright
And if it doesn’t exist, the point can’t either
The asymptote is at pi/2
I need sleep
ok
gn
so that should translate for all 3 of those problems right]
close.
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Can someone analyze this ?
Give me answers please
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can someone help w these simple trig problems
What is the problem asking for in number one?
find the measure of theta
the second is asking to solve the triange
triangle
so probably find all values or smtn
For number one, set up an equation: cos(theta)=12/13
in order to solve for theta, you need a calculator to find the cos-1
so plug in to your calculator cos-1=12/13
im trying to prep for a test, so are these possible w no calculator?
wait so when I do 12/13 what is my result
it's like 0.92
does that number mean anything or do i just plug in if i have a calc
Do you know if the teacher will allow calculators?
I havent learned any way to solve arc functions without calculator
yeah its a no calc test so they probably won't have problems like that on the test
one more question
so to find the measure of that angle, you go to your calculator and press the cos-1 button. and then it you put in cos-1 (12/13)
and whatever value it gives you is your angle
and to convert to degrees do i just divide by 180
to convert radians to degrees?
to convert a radian to degrees just substitute 180 instead of the pi. For example if you want to convert 3pi/2 radians into degrees, you substitute 180 in for the pi....so it would be 2(180)/2....and then simplify that fraction
that would be your angle in degrees
ohhh i see gotcha ok tyty i get it
one more question
its about graphing
how would u approach graphing this
like i dont understand how to get started
i know about even roots and all that stuff
First I would determine the end behaver of the function by looking at the leading term. If the degree of the leading term is an even number, the graph will look like a parabola
if its odd, the graph will look like a trig graph
Then find the zeros of the function. The x intercepts.
for that function you would have to use synthetic division to know where is crosses the x axis
honestly tho...
to make life easier
to graph that, just find points
so plug in a random number for x in that equation and whatever value you get from solving it is your y value
plot that point and then continue doing the same thing until you get a graph
yeah
and it ends positive
yeah
wait so say I did the division what would i divide by>
?
because we learned about division and stuff so i'm assuming she wants me to
do that
have you covered synthetic division yet?
ah yeah that kind of division would work
if you do that division you will be able to find the x intercepts of the function
oh ok so w the function i showed above
what would i divide by?
or how do i find what to divide by?
its honestly trial and error....usually you divide by factors of the last term. so you could divide that equation above by (x-2)
if you get no remainder for that division, then 2 is a x intercept
if you get a remainder, then you have to choose a different number and divide by a different linear factor
oh wait what, so will the factor always follow a (x - someting) format
or do i need to think about smtn in front of the x too
yes, you will always divide by (x - something)...that is your linear factor
wait ok say say i get a problem and they give me one intercept like (3,0) or smtn then the factor would be x - 3 right
and i can divide to find the rest?
yes exactly!
if they give you a negative number like (-3,0) then make sure you divide by (x+3).....it would be like this: (x-(-3)) and that would turn into (x+3)
ohhhh i see ok gotcha, I have a feeling they'll give me 1 x-int if it's on the test
so that's probably what it'll be
also
back to cos and sin say I get smtn like cos(7x/4)
how do u use the unit circle to help w that
or sin (180)
no calculator
ummm honestly just memorizing the unit circle is the best way to help
sin of 180 is 0
oh yeah I think ur right
ok last question how would u solve a problem like "if an eight foot stop sign casts a 10 foot shadow, what is the angle of the elevation to the top of the sign"
like I get it makes a triangle
u only have 2 digits
and the hypotnous is like the squareroot of 164 or smtn
do u use the law of cosine or whatever?
no you use arc functions again to find the angle
your given the opposite side length
and the adjacent length
so you would plus into your calculator tan-1 (8/10)
and then whatever it gives you would be the angle
ok so if i'm given 2 side lengths should use my calculator and find the inverse right?
the onoy situations whre I don't is if im looking for an angle
and I can do soh cah toa?
rigth
if your looking for an angle and you are given side lengths, you need to use either tan-1, cos-1, or sin-1. depending of what sides it gives you. if it gives you the opposite and the hypotenuse, and it asks for the angle then you do sin-1 (opp/hyp)
oh I see but if it's a right triangle and im given one angle aside from the 90
i can figure out the other
and use the law of cosine to find sides?
is that how it works?
wait no i just read abt it i get it now
so law of sine when given 2 angles one side
anyways I appreicate all the help sm
i needed to prep for a test and this helped tons
thank u
yeah np
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i know i subtract a+4 to get the whole function = to 0
but where do i go from there?
@proven bobcat Has your question been resolved?
you can then multiply both sides by (a-9)^2
after you’ve taken denominator common
this makes sure the inequality doesn’t change
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When math books explain formulas with variables such as (a + b)(a-b) = a^2-b^2. Should I read the right side actually as (a)^2-(b)^2 ?
um
if u wanna touch on how to actually read it
mayb write in latex first
so
$(a + b)(a-b) = a^2-b^2$
whats the difference?
$(a + b)(a-b) = (a)^2-(b)^2$
$(a + b)(a-b) = (a)^2-(b)^2$
ha
$x^2 = (x)^2$
illuminator3 (#eric4honorable)
unless x itself has an exponent, i suppose
i made a mistake because i interpreted it wrong so that is why I asked.
I wrote 16y^2 as 4y^2
no?
(x)^2 may be safer?
what?
safer 
$16y^2 = (4y)^2$
its the same, might be easier to see how exponent laws work though
Yup that is why i asked should you put braces around the variables in textbook formulas.
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yo
help a brother out
go get your own channel bruv
Sorry
!15m
Please only use the <@&286206848099549185> ping once if your question has not been answered for 15 minutes. Please do not ping or DM individual users about your question.
alr bro mb
you've been here long enough to know you shouldn't be doing these things
there are no rules against pinging individual people
bruv is there
mb if there is
ill wait patiently
what do you usually do to simplify fractions?
3/2 = x
the bases different
what do you do to find x
isnt x=3/2
okay lets not take that example, lets take y=5/8
alr
how do you get rid of the fraction?
there we go
same laws here, multiplication is your friend
except you have to multiply exponents now
do i log both sides?
how do you multiply exponents?
no no
im kinda lost
not quite yet
are you sure? will it get rid of the fraction?
raise to the power 2, yes
i got x3?
x^3 = ?
there we go
OHH SHT
then x=?

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hi
I'm having trouble understanding this part of the steps to a question I'm doing
What are you having difficulty understanding?
1 (mod 40) is like saying 40n + 1. It could be 41, 81, 121, etc.
well the one i'm trying to find is 3d =1(mod20)
20n + 1 = 3d
You're looking for a value of n that results in an integer d.
sorry... how do i do that
41/3 does not return an integer.
Yes.
so 7 is d
Yes.
ohhhh
so like if y=cd (mod m)
that means
y=c7(mod 33)
but if i don'T know c how can i get the answer
$y = C^{d} (mod m)$
Kookiemon
Use the encoded message for the values of C.
Use one character at a time
,wolf 0^7 (mod 33)
That depends on if 00 and 08 are two letters or four letters.
They way it is written in the problem would indicate they are just two letters.
So you would just decode 8 next.
No, m is used to determine the prime factors p and q.
Then (p-1)(q-1) is how you find theta.
From there, you use e in the formula
$de = 1 (mod\ theta)$
Kookiemon
And that will allow you to solve for d.
Yes, you use the d you found to decrypt the message.
$y = 00^7 (mod\ 33)\
y = 08^7 (mod\ 33)$
Kookiemon
so if the first number is 0 and the second number is 3 does that mean the answer will be ac?
wait how did it change to 8 to the power of 7?
The encrypted message is 00 08.
yw
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Evaluate the limit of 𝑓(𝑥) numerically or state that the limit does not exist.
𝑓(𝑥)=(4cos(𝜃)−4)/5𝜃
(Give your answer as a whole or exact number. Use the symbol ∞ for infinity. Enter DNE if the limit does not exist.
lim𝜃→0𝑓(𝑥)=
bruh i am stuck on this for a lot of time
<@&286206848099549185>
pls
welp
i have tried approximating it from both sides(x=0.001, x=0.0001 and x=-0.001, x=-0.0001) but i cant find it
factor out 4/5
then look at the limit again and see that it is the limit of a certain derivative
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An idea?
When I'm trying to transform the cos(3x) in a cos(2x) thx to the cos(a+b) formula, i have an expression who looks more complicated
,tex \trigangles
ew what are these colours
lets change it then
In what it helps me x)?
I think u can make a cubic equation out of this
what is the question?
anyways this might help u
I'm guessing u have to find the general solution for x, there u go u can move on from here
ping if u need more help
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State a single vector equal to:
b) 𝑃𝑊⃑⃑⃑ − 𝑉𝑃⃑⃑⃑ c) (𝑅𝑄⃑⃑⃑ + 𝑅𝑆⃑⃑⃑ ) + 𝑉U
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If |𝑎⃗| = 3 and |𝑏⃑⃗|= 2, and the angle between these two vectors is 60, determine (3𝑎⃗ + 2𝑏⃑⃗) ∙ (4𝑎⃗ − 3𝑏⃑⃗)
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So I have been told that a monomial is not a polynomial
I do see how x^4 would be a polynomial because you could add 0x^3 + 0x^2 + 0x^1 + 0 to make it multi term
depends on the monomial
pi is a constant yes,
and would be classified as a polynomial
So it is not a rational function?
it is
polynomial/(another polynomial; not 0) is correct
Constant is a polynomial too
Because a constant can be multiplied by x^0
but 0 is a special case. F(x) = 0 is not a polynomial function but a zero function iirc?
Zero degree
which makes it a rational function
Special case no?
I mean just this on its own no division
if you can express it as polynomial/(another polynomial; not 0)
its a rational function
0 can be expressed as 0/1
or whatever
which satisfies the definition
We can call this a zero function according to Professor Leonard
Oh.. he stated it’s a weird one.. not the same as constant like 9
Alright thanks.. I will make note of this
Thank you so all three examples above are rational functions got it
So that would mean this last one is a rational function too then? By definition as per above?
no, division by 0 trumps that
Lol.. but we already stated 0 is a polynomial
technically it would be poly/(non 0 polynomial)
Ooo OK, I will add that in definition
but no division by 0 is pretty much standard that people don't bother saying it
It’s undefined right? The last example
yeh
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Hi
I want to check if what I did is correct for proving theorem 1.9
First let Y be an infinite set
So Y is in N or N is in Y(N is the set of natural numbers)
If Y is in N then Y is countable
Let a_n be the greatest element in Y
Uh, you want to be careful with "is in" there, what you said isn't true
I mean that it's included in it
Right, that's not true
What's wrong with that
For example, the set of real numbers (0,1)
Neither is N included in it nor is it included in N
Oh yea you are right
So it's not that easy to prove after all
Then how should I work this
Can you lend me a hand in this
Let's see, I would probably do something like: given S infinite, try to construct a function f(n) which is an injection from N to S
Then the image of N under f is the subset you want
But what if S is included in N
No problem
There are injections from N to proper subsets of N, like f(n) = 2n
That's injective, and it maps into just the even naturals
This won't work in this case beacuse there will be elements of N that won't have images in S
That's okay, S can be really really big, it just has to be at least as big as N
You don't have to hit all of S to prove that S has an infinite subset
A countable subset, rather
You just need to hit countably infinite many things
If S is infinite then it directly have an infinite subset
But the countable part is the deal
Yes
Do you see how providing the injection I mentioned above shows that S has a countable subset?
I don't know if I really got that or no
you're creating a countable subset because you're listing the elements. f(k) is the k'th element
Doesn't this contradict the theorem bc this is an infinite set and doesn't have a countable infinite subset ?
it does
Why do you think it doesn't have a countable infinite subset?
Oh
Do you think countable sets have to be made up of natural numbers?
They don't -- there has to be a bijection between them and the set of natural numbers.
Yea you are right bc if there is a bijection between the set and natural numbers then there cardinalities are equal
So I can use this as the function that maps from N→S ?
that's how rsb defined it
He just asked me to find an injection between N and S he didn't say anything about this function
Ok but after defining this function I'll have to show that it is a bijection ?
Yes, a bijection between N and ... ?
S
Not quite
And an infinite subset of S
Right
Which can be S\least element of S
S might not have a least element
These are just sets, they might not even have a sense of ordering
S is non empty so it should have a least element
what function?
What's the least element of (0,1)?
0
0 isn't in that set.
Oh yea you are right
(0,1) means: all x that are strictly greater than 0 and strictly less than 1
Yea ik just made a stupid mistake
This has no least element ..
Bc you cant reach a least element
You can take an element closer and closer to 0 as much as you wish
Let's start by trying to find a countable subset of (0,1) though, that seems like a good start
Ok
how about this one: {(1/2), (1/3), (1/4), (1/5),...}
Ok
Do you agree that that's countable?
Correct
And n is in N
no
Actually I think the nth elemen t is 1/(n+1) but close enough
Yea you are right I made this as a mistake but ik the concept
Yeah, I think you know the concept
Coming up with this for an arbitrary set S is a little trickier
The proof goes something like this: since S is infinite, it must have some element, call that s. So we let f(1) = s. Since S is infinite, S{s} must also be infinite, so it must have some element, call that t. Let f(2) = t. Since S is infinite, S{s,t} must also be infinite, so it must have some element, call that u. Let f(3) = u.
Etc.
To get the exact formal definitions and so on depends on the conventions of the book you're reading, but a construction like that is broadly how I would prove this theorem
oh so you are doing something similar to using least element principle but instead here doesnt depend on a least element
Just need there to be any element at all
ok but after defining this function i have to prove that it is bijective am i right ?
Yeah, but its injective by definition
yea
And every injective function is a bijection with its image
if it's bijective then N and S have the same cardinality which is not necessarily true
wdym by that
No
if they had the same cardinality the problem would be trivial
Because it's a bijection with the set {s,u,t....}
not with the set S
It's a bijection with some subset of S
yea and since it is a bijection with a subset of S then this is what proves it
Right
every injection is a bijection with its image but there may be elements that dont have images
so shouldnt i prove that its a surjection too
??
"elements that don't have images"?
oh wait {s,u,t...} are images of elements in N
Right
X = {s,u,t...}
$X \subseteq S$ and $f$ is a bijection between $\mathbb N$ and $X$ is what we need
RSB
what i meant is that if it is an injection that doesnt mean that all images in the codomain have elements that map them in N
i mean that elements in S should have 1 element in N at most
so there may be elements in S that doesnt have an element in N
Right, that's $X\subseteq S$
RSB
OK is it clear that $f$ is a bijection between $\mathbb N$ and $X$ ?
RSB
but then the subset X has all the elements images of elements in N
and we need X we dont need S anymore
yea
bc f is an injection between N and X and since all elements in X are images of elements in N then it is bijective which settles it
but how do i define the function f
We defined it right here
i mean how to define it symbolically
ohh
S could be anhything, the set of reals, of cats, of hairs on my head, of words, of rubiks cubes positions...
Gotta run now, though. Hope that helped!
so its ok to say let f be a function where f(1)=s where s is in S and so on ?
Yeah I think that's fine
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yo can someone do my whole algebra test
did u know that 2+1=4
oh mb some indian scamme rkid took mu phoen
?
.close
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man
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3a
Just find f'(1)
im confused
Differentiate 3x^2 + 4x and plug in x = 1
7?
Then why are you trying to solve these questions, without knowing how to do the math?
i mean that’s kinda why i asked cuz i don’t know where to start
learn differentiation
In this video we look at how to differentiate and function and the different types of notation associated with it.
my teacher never taught us that yet so i’m assuming there’s another method
Prolly approximate using the slope of a secant whose endpoints are near the desired value
The computation is standard (I assume) so I'll leave that to you
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I'm trying to show this isnt a vector space
but something is confusing me
if I have the constant function f(x) = 1
axion 6 states (c+d)x =cx +dx needs to hold
but how do I handle c+d? the way I would normally or as stated by V = F(R)
c and d are constants but just like f(x) we can have constant functions
is F(R) functions from reals to reals?
yea
V is an R vector space, so c,d are reals
and x is a function
(assuming I correctly guessed what axiom you are referring to, might help if you post the full list)
c+d is a real
so you use the second line of the definition
(notation is a bit trippy here)
Ok so there is a clear distinction between c = 1 and f(x) = 1?
on the left of the equals in the definition, yes. On the right, no
So (c+d)*f is the function (c+d)+f
on the left, (c+d) is still formally a real number
but on the right, its something you add to f to make a function (so you can treat it as a function)
(it might probably help to use slightly different notation for each side)
ty
@wraith hinge one more question for this situation
does axiom for additive inverse hold
since x + 1/x = 1
and h(x) = 1 is a zero vector for F(R)
or well actually I guess this doesnt work for f(x) = 0?
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hello
just the same as f prime
The slope at a specific point, you could say
And yeah, that is just the derivative as ZO37 said
How can I find it
Do I j have to find the derivative
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@gloomy fern Has your question been resolved?
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This isn’t making sense to me
the Q?
Hold on it’s not uploading
lol
Smh

what is the normal to
hv u learnt derivatives
tangent line?
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$\lim_{x \to 1^{+}} \frac{2x^{2}-x-1 \sin(x^{2}+3x-4)}$
wowowin123
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this
lol
as x approaches 1 to the right
how to i find this kind of limit
am i allowed to factor the polynomial inside the sin func?
you are allowed
it would be sin(x-1)*sin(x+4)/(2x+1)(x−1)?
sin((x-1)(x+4))/(2x+1)(x-1)? Am I allowed to use the trix identities sin(x)/x = 1 on this?
nope
its a good intuition though
and with more advanced math this idea is essentially good
but for now i suggest l'hospital
is the answer would be similar if i use that to the conventional way?
wdym?
lhospital wasn't part of my discussion on school yet
so i might think if i approach a problem
using that
yeah its hard
but maybe you could force it to appear
like what if you multiply on top and on the bottom by (x+4)?
then you would get something of the form
sin(y)/y
do you see what i mean?
yeah i see where you are going
i might study lhospital to make sure of my answers
thanks for this!
just use this hint i gave you and post the answer back and ping me
i'll tell you if its the right answer
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How can you have two equal signs? is this legal?
Is this another way of saying make any term equal zero and due to the zero multiplicity rule, the entire output will equal zero?
yeah that's pretty normal it just means that you have two equations
f(x) = 7x²(x-2)(x+1/2)⁴(x+3)⁵
And
7x²(x-2)(x+1/2)⁴(x+3)⁵ = 0
and yes to that second part
So underneath it should say 7x²(x-2)(x+1/2)⁴(x+3)⁵ = 0 but maybe the instructor got lazy?
It "shouldn't" do anything because both notations work
OK, it's just weird to see equals and then another equals, I will have to get used to that...
In fact, you can have any number of equals signs
2/2 = 4/4 = 6/6 = 8/8 = 10/10
so I can read this as: "put in a certain input to make the entire function equal zero as the output?
and there are a few ways to tackle it (4 that I can spot), to make any term equal zero
and due to the zero multiplicity rule, all of it equals zero
having a zero term is like pacman it will eat them all up
I prefer to think of zero like a bomb, because eating seems like you eat one thing at a time, while zero blows them all up and leaves nothing
But yeah
abcde = 0 means a or b or c or d or e = 0
That's like blowing up zero times, which means you leave only 1 thing
lol
So yes to that, f(x) is defined like ( ... ), and we want to know when is f(x) is equal to 0 so in other words f(x) = 0 => ( ... ) = 0
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Hi I am having trouble proving this lemma from real analysis
below is my work so far, I am a bit confused on how to show $r < s^2$ will get me $r(\frac{1+s}{r+s})^2 > 1$ since we know that $r(\frac{1+s}{r+s})^2 < s^2(\frac{1+s}{r+s})^2$
OhGumbus
I think I may have already proved it, but I am unsure if just saying that since s^2 is a positive number bounded by one and r is also a positive bounded by 1, that the claim holds.
<@&286206848099549185>
@upbeat plover Has your question been resolved?
I'd start probably backwards
Try to turn the target inequality into something without fractions
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hi, this is not exactly a math question, but do anyone know a book where I can practice nonlinear system of equations like this?
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idrk where to start tbh
try to remember how 1/sinx graph looks like
hmm okay well then nvm
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the bottom statement
if we do
3 ≡ 5 (mod 2)
b should be 1
when using a = b + kn
wait nah
wont b be a decimal
5 is not a number in mod 2. If you have a, you're solving for b by dividing by n, and the remainder is b.
3 = 5 + k * 2, implies k = -1, or
5 = 3 + k * 2, implies k = 1
both -1 and 1 are valid residues here
so its not saying a ≡ b (mod n) can be written as a = b +kn
why not?
Am I fundamentally misinterpreting 5mod2
a-b = kn. so k=(a-b)/n. is that your question?
they shouldn't have called b the remainder in the image
a remainder is usually implied to be less than n
yeah thats what i was confused with
idk we talking about (mod 2)
like
1 in mod 2
It should be 1
