#help-38
1 messages · Page 179 of 1
I just gotta do some more practice questions
alright i will try
Alr ty
bcs it contains 'cot' 🥴
😭
OK, so the degree I chose is not random, but rather a degree that has the same value as the result we want to find, like this, tangent theta is equal to 1, I'm looking for the value of tangent which has a value of 1, and has a POSITIVE value.. i hope you got it
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matrix/linear algebra
So many 
do you expect people to do your entire homework for you?
its just 2 problems amr
look at all the parts
i sent 3 problems...
theres 13 in the whole set i did most of them lmfao
these are the ones im stuck on
Well then, have you tried anything? Do you have any idea for any of them?
@raven plume Has your question been resolved?
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can someone explain to me why v >u here
v is the velocity of the rocket relative to an external observer and u is the velocity of the gas relative to the velocity of the rocket
this is about the rocket equation
M_0 is the intitial mass of the rocket and m is the total amount of gas outputed by the rocket
@fluid shale Has your question been resolved?
OOOOH I GET IT
is it assuming v_0 = 0 ?
i guess there is no initial velocity
and then v(t) = u ln ( M_0 / M_0 - m (t))
so v (t) / ln ( M_0 / M_0 - m (t)) = u
and if that number is bigger than 1 then v would neccessairly have to be bigger than u
to compensate for that
is my logic correct that they assume v_0 = 0
@fluid shale Has your question been resolved?
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man just use chain rule
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but ok you can use product rule
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$\frac{d}{dx} f(g(x)) = f’(g(x)) * g’(x)$
knief
yea
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this is the chain rule
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It's not part of the chain rule
You find the derivative though
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i was just showing you what the chain rule is
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✨ khan academy ✨
cardinality go brr
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unfortunately you’re wrong
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why the -2sinx
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yea
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bulgogie
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nothin
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because bulgogie
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this is 2(-sin^2 + cos^2)
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zyzz
yuh
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but also rewrite in terms of cos(2x)
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cos^2 - sin^2
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sure
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$-2\sin^2(x) + 2\cos^2(x) = 2(-\sin^2(x) + \cos^2(x)) = 2\cos(2x)$
knief
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💀
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double?
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^
it’s angle sum mate
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what
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💤
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😴
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why sinx
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huh
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oh
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it says in the second part
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oh this is another question lol
you didn’t differentiate it
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man this is so evil
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😭
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not teaching you chain rule
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it’s arguably the most important rule
they’re making you differentiate cos^2 and sin^2 using product rule too
😭😭
instead of power and chain rule
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goodnight
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you’re welcome
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H
,rcw
Limit as x tends to 0 probably
I don't know
hello
Can you ilucidate
what
Might use the Taylor expansion of sqrt(1 + x) around x = 0 if you had that already
I don't know taylor expansion
I'm not entirely sure what the exercise wants because I don't have any context on your course. Maybe it's enough if you just show that f(0) = g(0), f'(0) = g'(0) and f''(0) = g''(0)
expand both the brackets and multiply the 2 brackets
Okay
How do you put zero
Are you there
Yes
$\sqrt{\frac{1 - 0 }{1 + 0}} = 1$
Kepe
$1 - 0 + \frac{0^2}{2} = 1$
Kepe
Which grade are you
The derivative of the LHS is $-\frac{1}{2 \sqrt{\frac{1-x}{1 + x}} \cdot (1+x)^2}$. Plugging in $0$ gives $-1$.
Kepe
The derivative of the RHS is $-1 + x$. Plugging in $0$ gives $-1$ too
Kepe
And the same for the second derivative.
But as I said, it really depends on what this exercise wants from you and what you previously covered in your course
But again, you should give more context
What have you done previously in class?
What topic are you currently on?
In binomial expansion
Then follow this
Okay
What I provided are just two alternatives then
Yeah one could say so
In high school and in uni in parallel
I'm 11rh
Cool
I started 12th recently
Advice on what?
Math
Like generally?
Yes
It's best if you really like it, hopefully even love it
hi
Do you follow youtube channel to get help
No
If I want to look up a school topic, I look it up in the book
For uni topics, I look them up in the lecture notes
Or in books
No internet and gained so much knowledge
Why don't you accept my friend request
Oh I didn't notice it
I'm Indian
Oh, cool
You must know of Ramanujan, right?
A pretty good mathematical inspiration
We are Brahmins
There is a movie about him
Good right
Yeah it's absolutely great
Maybe we will even watch it in class
My teacher has it
He is a treasure
Very mysterious
He described to his friends that he saw a bloodstream
Then a hand drew elliptic integrals into it
The next day, he would remember it and write it down
He attributed everything to his goddess Namagiri
Yeah, together with Hardy
German people are smart
Johannes Kepler
Well Gauss and Euler would probably be the biggest I would name
Anyways, I gotta go now since I have to give a presentation to my teachers soon
About what
It's because I'm in university at the same time as high school
And they wanted me to present any topic I choose
I chose the jordan normal form
It's a nice form you can get matrices into
Do you know aryabhatta
He discovered zero
do yall like n||u||gge||ts||
Later, the naturals were formalized by Peano
There are now if I remember correctly 5 or 6 peano axioms
Basically describing what the set $\mathbb N$ should be
Kepe
Well anyways, I'm gonna go now, cya
bro why u ignoring mme
@paper estuary Has your question been resolved?
Yes
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.
I put DNE since at X = 1, it approaches a local maximum but dne
Then I put 4 because at X = 6 there is a local maximum
Oh I got it
I need to include the absolute maximum since it's in the middle
.close
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This is a problem related to Taylor Series, Im trying to find the Taylor Series for
x² . ln(x) with x₀ = 1
Doing the derivates, i found that the Series is divided into some sections [1st Image]. Them being: Two derivatives which dont seem to form any clear pattern
1st 2x . ln(x) + x
2nd 2 ln(x) + 3
All the following have a (2(2(n-3)!) . (x^(n-2)) pattern, starting from n = 3, alternating between positive and negative, which, after a lot of time, i was able to figure as the next sum [2nd image]
From there, I replaced all corresponding x₀ with 1. [3rd and 4th image] to be able to form the polynomical form, but it didn't work.
I'd like to know if i did something really wrong
@slim temple Has your question been resolved?
@slim temple Has your question been resolved?
@slim temple Has your question been resolved?
@slim temple Has your question been resolved?
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I need help with this problem, deals with Parabolas.
Consider the function f(x)=(2x)^2 - 2
Describe each function as a transformation of the quadratic parent function.
I am having trouble about horizontal stretching or compressions.
I thought it is horizontal compression by 2 but the key says horizontal compression by 1/2. I am confused.
@grim mauve Has your question been resolved?
Yeah but if it gets squished, shouldnt it be get squished by a positive number? If it gets squished by a fraction shouldn’t have it gotten wider?
again this is just the wording being weird
Ok
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on the interval [0, 2pi] this dip would be a local minimum right? not an absolute one?
i dont think there's an absolute minimum here but i wanna make sure
ye
because at x = 0 the y value is higher
well assuming this is a normal polynomial cubic function
the absolute minimum would be at y=-inf
because all polynomials are continuous
even with the interval?
not with the interval
it says find the absolute minimum and maximum values on the interval [0, 2pi]
then yeah that would be the absolute minimum and maximum
only for that given interval
so no abs minimum?
abs minimum on that interval would exist
but wouldnt it be local
its constrained to the interval
pretend everything outside of that interval does not exist
oke
look
your view is constrained to this about
who is to say that to the left of this
this wouldnt happen?
so yeah you kinda just have to assume its an absolute min
why can we assume O.o when it could go in either direction
its just that you have no information so you assume from what you are given
dont get fixed on the semantics :p
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Find all values of c such that f(x) has 2 integer roots, where f(x)=9x^2-12x+c
I used the the quadratic formula to get that
$\frac{\left(12\pm\sqrt{144-36c}\right)}{18}$ has to be an integer
TimesZeroed
Only way for this to be true is if
$\left(12\pm\sqrt{144-36c}\right)\operatorname{mod}18=0$
TimesZeroed
12 = -6 (in mod 18)
and then I added that to the other side
$\pm\sqrt{144-36c}\operatorname{mod}18=6$
TimesZeroed
the sqrt simplifies to 6sqrt(4-c) if that helps at all
TimesZeroed
Checking on desmos, the first solution is x=3
This is a pre-calc question
so I think I am overcomplicating it
ill try to aproach it from some other way to see if i can help, but this seems like this should be easy, yeah
I am going to post the exact problem
- Using the discriminant:
For what values of c will the equation
9x^2-12x+c=0
have
a) no real roots
b) one rational root
c) two real roots
d) two integer roots
the first should be a c > a with a being some real positive number
the second is c = a
yeah, thats a real positive number
yeah
ill do some math for d), but maybe it has something to do with previous answers, ill check
wolfram alpha claims
these are the integer solutions
but I don't know if it produces
2 integer solutions
or just one
yeah
it just produces one integer solution
or only guarantees one integer solution
this is what i could advance with, it may lead to something i guess
i missed a /18 on the whole root
oh, sorry, i got it wrong, still i had a good idea-
yeah
anyway
so you got
sqrt(stuff) = n
ohh
that's nice
you just need 4-c to be a perfect square
nvm
it must be (1+3n)/3, sooo, like, 1/3, 4/3, 7/3 for it to make up an integer while adding with 2/3
yeah
but
in the quadratic formula
you get
nvm
your write
actually
yeah c has to be an integer
in the quadratic formula
you get
sqrt(144-36c)
you factor out the 36
6sqrt(4-c)
ohh
c can have a denominator of 36 at max
my bad
yeah, i was doing exactly that, i ended with
sqrt(4-c) = 1+3n
so infinite answers, now to find the pattern it follows
you ^2 both sides and gives -c = 9n^2 + 6n - 3 * with n being any integer
i think that would do 
sorry, its minus c
sooo, basically c = -9n^2 - 6n + 3 , n = any integer.
it also makes sense, since that formula "mostly" gives negative numbers, and the answer as sqrt(4-c), which cant have any c > 4
i think, yeah
alright I will check it
but thank you so much
I've just been
searching for value
by repeatly clicking on a->
mfw i dont know how to use mod because my country education doesnt use it at all
lol
dang
anyway
Can you explain your solution
yeah, ill try to send it in LaTeX, wait a bit
thanks
here is my solution finder
it's very inefficient
but it is no longer manual
I haven't found any below 2000
Okay
I checked your formula
and it seems that it only gives value where there is one solution that is an integer
the other is 1/3
so I think the answer is that there aren't any
i also find a problem, ill end the latex thing and check on my logic 
sorry for the mess
$\frac{12 \pm \sqrt{144-36c}}{18}=x_{1},x_{2\in}\in \mathbb{Z}\ \frac{2}{3} \pm \frac{\sqrt{144-36c}}{18} = \mathbb{Z}\Rightarrow \pm \frac{\sqrt{144-36c}}{18} =\frac{1+3n}{3}\ \pm\frac{\frac{\sqrt{144-36c}}{6}}{3}=\frac{1+3n}{3}\Rightarrow\pm\frac{\sqrt{144-36c}}{6}=1+3n\ \ast \sqrt{144-36c}=\sqrt{12^{2}-6^{2}c}=\sqrt{(2.6)^{2}-6^{2}c}=\sqrt{(6)^{2}(2^{2}-c)}=6\sqrt{4-c}\ \pm\frac{6\sqrt{4-c}}{6}=1+3n \Rightarrow \pm\sqrt{{4-c}}=1+3n\Rightarrow (\pm\sqrt{{4-c}})^{2}=(1+3n)^{2}\ 4-c = 9n^{2}+6n+1\Rightarrow -c = 9n^{2}+6n-3\Rightarrow c = -9n^{2}-6n+3$
zzz0nnn
for example, n = 0, which is an integer, makes c = 3, which is one of the solutions
no? :(
if the substract and sum part share solutions then there are solutions 
ill make the same logic, wait a bit
like, i divided the problem in sum and substract without realizing
its the same problem but with 2+3n instead of 1+3n
$-9n^{2}-6n+3=-9n^{2}-12n\Rightarrow \ -6n=0$
zzz0nnn
so the only answer to check is n = 0, which we know is not answer
so no solutions right
yeah, id swear
what i just sent you is the full proof, it just need the 2+3n version
i can do it if you want
Before you try
I think
proving that (-6 + y) mod 18 = 0
then -6-y mod 18 can't = 0
is eaiser
because of -6 + y = 0 (everything is mod 18 for now)
then y = 6
-6-6 = -12
which mod 18
is 6
nvm
Ok I got a better proof
if you use the quadratic formula
and simplify it
you get
$\frac{\left(2\pm\sqrt{4-c}\right)}{3}$
TimesZeroed
TimesZeroed
has to be true
when it is plus
this is only true when y is of the form
3n + 1
and when it is -
idk what the fuck u doing but go ahead, slay > again im not into mod, i usually use other methods
yeah this doesn't require mod
you have 9x^2-12x+c=0
right
yeah?
$\frac{12 \pm \sqrt{144-36c}}{18}=x_{1},x_{2\in}\in \mathbb{Z}\ \frac{2}{3} \pm \frac{\sqrt{144-36c}}{18} = \mathbb{Z}\\ + \frac{\sqrt{144-36c}}{18} =\frac{1+3n}{3}\ +\frac{\frac{\sqrt{144-36c}}{6}}{3}=\frac{1+3n}{3}\Rightarrow+\frac{\sqrt{144-36c}}{6}=1+3n\ \ast \sqrt{144-36c}=\sqrt{12^{2}-6^{2}c}=\sqrt{(2.6)^{2}-6^{2}c}=\sqrt{(6)^{2}(2^{2}-c)}=6\sqrt{4-c}\ +\frac{6\sqrt{4-c}}{6}=1+3n \Rightarrow +\sqrt{{4-c}}=1+3n\Rightarrow (+\sqrt{{4-c}})^{2}=(1+3n)^{2}\ 4-c = 9n^{2}+6n+1\Rightarrow -c = 9n^{2}+6n-3\Rightarrow c = -9n^{2}-6n+3\ \ - \frac{\sqrt{144-36c}}{18} =\frac{2+3n}{3}\ -\frac{\frac{\sqrt{144-36c}}{6}}{3}=\frac{2+3n}{3}\Rightarrow+\frac{\sqrt{144-36c}}{6}=2+3n\ \ast \sqrt{144-36c}=\sqrt{12^{2}-6^{2}c}=\sqrt{(2.6)^{2}-6^{2}c}=\sqrt{(6)^{2}(2^{2}-c)}=6\sqrt{4-c}\ +\frac{6\sqrt{4-c}}{6}=2+3n \Rightarrow +\sqrt{{4-c}}=2+3n\Rightarrow (+\sqrt{{4-c}})^{2}=(2+3n)^{2}\ 4-c = 9n^{2}+12n+4\Rightarrow -c = 9n^{2}+12n\Rightarrow c = -9n^{2}-12n\ \ -9n^{2}-6n+3=-9n^{2}-12n\Rightarrow \ -6n=0$
this is the whole thing, kinda messy, you just add that n = 0 is the only option and it doesnt work in neither of the formulas
and thats the whole proof
zzz0nnn
we could also have gone for the geometric proof, which would have been far easier but just needed to write a lot 
cool
can I show you my proof
it's a lot a shorter no mods
nvm it's fine
thank you for the help
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Prove that $gcd(0,0) =0$
Mr bean is not $\R \setminus \Q$
The definition of gcd(a,b) is as follows, for a,b \in \Z
i feel like this depends on which definition you choose to take on
whether if a|b is written as b = ak or b/a = k (personally i dont like the latter definition but idk whats conventional definition elsewhere)
Let $gcd(a,b)=k$ . Then $k \mid a; k\mid b$.
\
if $l \mid a \land l\mid b \implies l\mid k$
Mr bean is not $\R \setminus \Q$
so $0=kk_1; 0=kk_2$
Mr bean is not $\R \setminus \Q$
It's obvious that $0=k \lor k_1,k_2=0$
Mr bean is not $\R \setminus \Q$
now we know that $0=ll_1; 0=ll_2$ so $l ;l_1l_2=0$
Mr bean is not $\R \setminus \Q$
What do I do now?
We use $b=ak$
Mr bean is not $\R \setminus \Q$
ok idk why it took me so long to realise but
like u agreed, 0 = D*0, where D is just any positive integer + 0
Mr bean is not $\R \setminus \Q$
so then by our previous definition we have D = {0, 1, ...}
every number within that set also divides into 0
so gcd is just 0
oh right
that make intutive sense, ofcours, but then we'd have have prove that 0 is the unique natural number with this proerty
Probably not required this point. I'm learning proofwriting , not Number theory (:vomit:)
thanks dootud!
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help
it gave u what x is
no
x = 4y - 17
oh ya
you have to substitute x=4y-17 into the equation above
Find y
And then plug this y in x=4y-17
🍫
Yes
Wait
y=5
3(4y-17)-y=4
I find the y
12y-51-y=4 -> 11y=55 -> 11y/11=55/11 -> y=5
Clear ?
👍
this
help
#help
@bright seal
hello
<@&286206848099549185>
<@&286206848099549185>
sub in the equation for y = x + 9 into 4x + 7y = 19
4x + 7(x+9) = 19
Hi
whats after
<@&286206848099549185>
<@&286206848099549185>
<@&286206848099549185>
can u solve it please
do not ping helpers multiple time you can ping only once
oh ok
as for this you have y=x+9 substitute y in 4x+7y=19
then
what did you get
what is this equal to?
subtract 63 from both sides in this
teach me plz
now
multiply
1 min
@vernal bronze
Substitute y into it ig
$4x + 7y = 19\ y = x + 9$
Sukiyaki
Sukiyaki
Sukiyaki
then
x = -4
do you get what i did?
Because you having y = x+9 essentially tells you that
till her yes
after this
After this, you sum it up.
and make the variable on one side and numbers on another.
That would make it easiest to solve.
ok
yes
but you have to -63 on the other side as well.
yes
that wouldn't be right..
hm...
that isnt right.
well if you substituted the following numbers into your calculator,
you'd actually get...
,calc 4(-(17/11))+7((82/11))
Result:
46
y = 5 bro
wait a min
Yes.
y = 5 is correct.
okay, ill explain it in 1 text.
is this right sukiyaki
So, first you have two equations
$4x+7y=19$ - (1)
$y=x+9$ - (2)
So because you already have y, you can substitute into the first equation labelled 1. Now you'll have this; $4x + 7(x+9) = 19$
Of course when you expand it you'll get
$4x + 7x + 63 = 19$
Now, remove 63 from the left side, you should get
$11x = -44$
thus, x=-4.
Now substitute x = -4 into second equation,
$y = -4 + 9\ \therefore \text{y = 5}$
Sukiyaki
ywah x = -4 right
Yes.
the answer key is wrong
This is called elimination and substituion right?
Well...
You could perform elimination too
we call it like that
i did elimiation
actually, this is purely substitution
what i did.
i should learn pure substitution
because i found x by substituting y into (1) and y by x into (2)
well if you did elimination, it would be longer imo.
i learnt from
👉Learn how to solve a system (of equations) by elimination. A system of equations is a set of equations which are collectively satisfied by one solution of the variables. The elimination method of solving a system of equations involves making the coefficient of one of the variables to be equal in all the equations that make up the system, in ord...
But you could take 7y = 7(x + 9)
Ok
alright, notice that
3x + 2y = -6
2x + 5y = 7
ya the teacher is wrong
well, this would leave you a x + 3y = ...
i sent her an email
and you'd have to substitute here and there.
,rotate
let me see.
simply substitute x into the first equation.
hm
ans is 0
?
Yea, i got that as well which i found it weird lol
y = 0
y = 1-y -1
2y = 0
y = 0.
x = 1
yep, i'm p sure it's simply y = 0, x = 1
yeah
he is correct
yes, this works
or simply, you know what i'd do?
y = x - 1 right?
yeah
well yea lets not do my method
it'll get confusing
Anyhoo, this is how you can do it.
how did the x become 1
well you substitute y = 0 into x = 1-y
Well instead of me just giving you answers, let me see if you understand.
I'm going to give you two equations, see if you can solve it.
2x + 4y = 12
x = 4 + y
O
k
bro
are both of you friends? @wraith hinge
no
o..
no
okay
we are stranger to each other lol
anyways @vernal bronze are you able to answer it?
okay
lemem check LOL
which question are you doing
ye y = 2/3
So do you roughly get what you're doing now?
good
hi
hi
you can close the channel and let others use it if youre done @vernal bronze you can text .close
@vernal bronze Has your question been resolved?
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Isn't F'(x) just f(x) ?
so the integral is just 2f(x)e^x
= 2 sinx
after integrating -2cosx | 0, 1
= 2(1 - cos1)
how?
Yes
Differentiation of a definite integral
I think it was called Leibnitz rule or something
oh F and f are different
Did you try plugging this in
this thing is definitely greater than 1
but none of the options' upper bounds are > 1
,calc 2(1-cos(1))
Result:
0.91939538826372
HUH
No
OH LORD IM DUMB
sorry
but how would I do that without a calculator
im supposed to solve this without a calculator
no tables, no nothing
,calc 2(1-cos(1))*360
Result:
330.98233977494
Yea plug 1 into that expansion until you get the accuracy you need
oh alright
i think till x^6/6!
since I get 720 that way
alright, tysm! @zinc ginkgo
(i thought it was increasing in (0, pi/2) xDDD)
it is
why'd you ask
im in 11th
that question was a piece of cake compared to some other ones
thanks for the motivation!
this one took me a solid 10 minutes to solve
this is func and relation chapter right?
our teacher was telling us that 11th one is super ez
but 12th one
💀
integration
don't tell me you have never seen an integral S before...
Find f'(ø)
i have
cause of phy
but our one is not that hard
mostly just integrals trig or power rule
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• Show your work, and if possible, explain where you are stuck.
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• Type the command .close to free the channel when you're done.
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how to prove the forward direction
can i start with saying that if circumcenter and incenter are the same point then all perpendicular bisectors are also angle bisectors?
,w incenter
Is it like centroid and orthocenter
it is
but different centers
centroid is the one for medians
this one are centers for perpendicular bisectors and angle bisectors
What are you required to use to prove it?
Construction?
Vectors?
So plain geometry
yes
I mean if i can say this
then i think i am done
are u sure?
I think it works but idk how to prove it
just seems obvious to me lol
maybe i'm wrong
You can try assuming the triangle is not equilateral
how do i prove this?
You can use the angle bisector theorem
I'm not sure if that's the name but I will send a picture
i don't think my claim is riht
just because centers are the same doesn't mean they have to be the same line
since it's just one point
yeah that's the forward direction
not the reverse
if the centers are the same then that doesn't mean that those lines have to be the same either
i guess i know how to solve this though
if X is the incenter of ABC then it is equidistant from AB, BC, and AC
if X is the circumcenter then XA = XC = XB

