#help-39
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I solved this problem with y=ux, but I thought this substitution would be easier and I’m not sure why this is incorrect. Can someone explain the issue with my process here?
<@&286206848099549185>
So just to check - is the solution $x = A y^2 - 2 y$ for some constant A?
Pseudonium
my solution isn’t simplified, but it’s ln(x) - y^2/2x^2 - y/x = C
I got this
Using y = ux
I also think your working is correct (up to a sign error in an intermediate step, but it cancels out for the last line)
And it reproduces the answer i got when you do e to the power of both sides
sorry this is something completely different, I got confused
here’s what I got
Right… i mean i would just do e^ both sides to get rid of the logs?
Possibly after multiplying by 2
So $2 \ln(\frac yx) - \ln(1 + \frac{2y}{x}) + \ln(x) = D$
Pseudonium
Really there should be absolute values here
So you get $\frac{y^2}{x^2} \frac{1}{1 + \frac{2y}{x} } x = B$ for some arbitrary real constant B
Pseudonium
This re-arranges to the form $x = A y^2 - 2y$ for a suitable A which I can’t be bothered to figure out
Pseudonium
Oh I think $A = \frac 1B$ probably
Pseudonium
yeah I pretty much see what you’re doing
does that mean I was on the right track with my work?
Pseudonium
The next line is incorrect, it should read $- \frac 1y dy = \frac{1}{-v - 2} dv$
Pseudonium
So you inserted an extra minus sign
However the line after that and all subsequent lines are correct
And if you exponentiate your last equation, you get $\frac{y}{\frac xy + 2} = D$ for some arbitrary constant D
Pseudonium
Pseudonium
alright, I think I understand
I must have typed it in wrong or something
thanks for the help
Np
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I just need quick answear
Cuz I got confused atp
Xc = -j10 ohm
V = j10 V
I = ?
What?
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@tawdry atlas Has your question been resolved?
V=IR
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if anyone knows physics could you help please
i have 2 unknown variables and i dont know what to do
only thing i can think that could be right is assuming to friction to find Ft then find a then find mew but idk
Hi @dim timber
hi
like there is no need to consider acceleration
since both are in rest
and the question is dealing with static friction not kinetic friction
so a = 0
yes
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no problem!
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arent all choices wrong
@round heart Has your question been resolved?
yes n is a nonzero natural number
since this is a multiple choice, why not just plug in n = 1
and see which answer you get?
but now try plugging n=4k then you would get 7
where k is a non-zero natural number
hmm
(i)^n + (-1)^n + (-i)^n + (1)^n this repeates itself
so technically if its even or odd it becomes 0
but at last (i)^8n is missing so we have output as -(i)^8n = -(1)^4n = -1
repeats but without the last 1^n
yup
exactly
u add n subtract (i)^8n
so basically it is 2(i^n)+2(-1)^n+2(-1)^ni^n+1
no
this gives output 0
it doesnt
try any int
try n=2
ah yes this does
yeah exactly
but n=4 doesnt it becomes 4
no
+3 from the other terms that we didnt write
becomes 7
i^4+(-1)^4+(-i)^4+1^4+i^4+(-1)^4+(-i)^4=1+1+1+1+1+1+1=7
every natural number which is a multiple of 4 will give this
this alone proves that all of the given choices are wrong
this expression doesnt give a single result
depends on n
ok take your time
Only natural number is the given number?
n is a non-zero natural number
idk french
but the one who sent the question told me what it says
like it has multiple answers
yes
I think maybe the question is asking the best result between these 3?
hmm
because that wasnt the intention of any mcq that i saw eve
r
yeah i see so it depends on n congruence of mod 4
what did you get
it builds a step function
so technically what u said is right it does depend on n
what are the possible outcomes
.t tex If 𝑛 ≡ 0 ( m o d 4 ) n≡0(mod4), the sum is 7 7. If 𝑛 ≡ 1 ( m o d 4 ) n≡1(mod4), the sum is 0 0. If 𝑛 ≡ 2 ( m o d 4 ) n≡2(mod4), the sum is − 1 −1. If 𝑛 ≡ 3 ( m o d 4 ) n≡3(mod4), the sum is 0 0.
Rey
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lil bad tex
np i understood the content
but how did you reach this
how 1 like if you plug n=2 dont you get -1
well i just divided the cases
tried plugging in some values
and as i^n depends on n from Nx(1,2,3)
$2i^n+2(-1)^n+1+2(-1)^ni^n$
pirateking0723
this is the expression that we are trying to simplify
according to the values of n
its hard to proceed from here
@summer sundial
someone solved it in a handwavy way
for the cases where n isnt a multiple of 4
this sum is a geometric series with common ratio i^n
add and subtract 1
you will get -1+ a sum from k=0 to 7 with k being the number multiplied by n in the exponent of i
so this becomes $-1+\sum_{k=0}^7i^{kn}=-1+\frac{1-(i^n)^{7+1}}{1-i^n}=-1+\frac{1-(i^n)^8}{1-i^n}=-1+0=-1$
pirateking0723
we can sort it as every 4th interval becomes 0
for i^n
thats for sure
wdym
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but if you take it as a geometric series
then you need to reject all n of the form n=4k
but you cant do that
because it wasnt initially there
so you find the value of the sum for other values of n
and then do the n=4k by manually substituting that in the expanded sum
and then evaluating
am i right
Even for geometric series there are diff outputs
no how
i took any arbitrary n under the condition that it is not of the form n=4k where k is a natural number
Summation will be i^n(i^6n-1)/(i^n-1)
by doing this
but if you add a term to that sum
and then subtract it
Hm?
add and subtract 1 as here
leave the -1 that results
then group the other terms together
I dont get it ig
they will form a geometric series
initially what you want to evaluate is $\sum_{k=1}^7i^{nk}$ now this $=-1+1+\sum_{k=1}^7i^{nk}=-1+\sum_{k=0}^7i^{nk}=-1+\frac{1-i^{8n}}{1-i^n}=-1+\frac{1-1}{1-i^n}=-1$
pirateking0723
wdym by that
Hmm I see
again this is true for all n diff than 4k where k is a natural number
otherwise the num and denom will be 0
Well however it could lead to multiple outputs
how
for which values of n does the sum give -i
so you are saying each i^{kn} alone
...
not the whole sum?
so if n is congruent to 1 mod 4 it doesnt give 0
also if 2 mod 4 then it will give -1
Yeah
same thing when n is congruent to 3 mod 4
so it is 2 cases in fact
when it is cong 0 mod 4 and when it is cong something else mod 4
tysm and sorry if i wasted your time
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@fallen tartan Has your question been resolved?
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What does it mean by 16C
Is it asking to form an equation?
Is it asking for the slope?
@mortal marten Has your question been resolved?
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Hey I have calculated the fourrier transfomations of cos(t) and got the following result
Got stuck on how to use it to calculate the integral under it
@reef plinth Has your question been resolved?
@reef plinth Has your question been resolved?
<@&286206848099549185> if anyone's free
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What
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Where did he get the square from in this equation? howd 3/x = x/24 turn into x squared
multiply both sides by x to get rid of the denominator
oh is it because theres 2 x's
ah ok lol stupid question
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in desparate need of help 😂 gotten nowhere
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1
Hemisphere is basically half of sphere
hemi means half
Since the formula of sphere's total surface area is 4πr^2
Then half of it i.e. formula for hemisphere will be 2πr^2
so would i be right to do 2 x π x 11^2?
yes
ive got 242π as my answer but says its wrong?
im confused
obviously im aware theres a circle
but i thought there was nothing else to do
like to calculate
its a circle and a half sphere
you just calculated the area of the half sphere (hemisphere), but you still need to calculate the area of the circle
Sorry I din't read the question you are supposed to find the total surface area of hemisphere which is 2πr^2+πr^2=3πr^2
so i need to do this equation ?
You can just add πr^2 with this
242π x 11^2*π
that gives me 289001.7561???
i need to keep it as π
so how can i do that
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left and right limits
using table method
the table method or left and right limits?
for table method, you just keep plugging in values that get closer and closer to 3 and see what the limit approaches
yep
although you should go a bit closer like 3.01 and 2.99 just to be sure
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is this defined? what would be the result?
Please don't occupy multiple help channels.
i think so too\
but i have a feeling it might big $\big_cup{1,2}$
Ayanokoji
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Why?
by definition, x is in this iff for some i (with appropriate restrictions), x is in {1, ... , i}
the appropriate restrictions being i is either 1 or 2
so x is in that iff x is in {1, ...., 1} or {1, ..., 2}
so you're saying it's 2 sets in a set, and not just 1 set?
i mean 1 set with atomic elements
it is 1 set with atomic elements
then it has to be undefined right?
we can't do that
yeah
iff x = 1 or x = 2. Hence the set must be {1, 2}
to complete that
if it was {{1}, {1,2}}
then the generalized union would be {1,2},
so you're saying
this is the case?
But it's not that
then it generalized union on the set {1,2}?
Oh I get what you said here. If you meant that the union in your question is equal to the generalized union of {{1}, {1, 2}}, then you were correct
but this is not the case
but rather the A1 intersection A2...intersection Ai
those are actually equivalent notions
oh
generalized union of {A1, A2, A3...} is same as A1 union A2 union A3 ...
that makes alot of sense
alright
i think i understand
thank you very much mate
np
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do you know how to construct a secant line?
what does the problem mean by use limits to solve this? you're not allowed to make use of basic derivative rules or something, it is expecting you to use definition of derivative?
i would assume so
you use secant line definition. i.e. construct secant line at (-2,-1) to some other point on the line (a, 2/a)
well
do you know how to define a line based on just going through two points on 2/x?
so you know one of the points you want the line to pass through, (2,2/-2), which is just (-2,-1)
now what would a general other point on this curve look like
oh, it also helps to use point slope definition of line
i should say point slope form
do you remember derivative definition? so just use this and plug in x = -2 then evaluate the limit
that gets you the slope, then just plug it into a point \ slope equation
$\lim_{h\to0}\frac{\frac{2}{-2+h}-\frac{2}{-2}}{h}$
∫oosh (lemonsaurus appreciator)
so is this what you got?
do you know how to evaluate this limit?
what does the limit evaluate to?
this seems a bit more complicated than it needs to be
creating a common denominator between the top fractions is the right idea but don't really need to multiply the overall h denominator by everything too
so think about just multiplying the 2 / (-2+h) by -2 / -2 (which is just 2 / 2) and then multiplying the 2 / 2 by (-2+h) / (-2+h)
and after some small simplifcation youll get a lone h which should cancel with the overall h denominator
should probably work your way too but dunno why im not seeing where things are canceling
maybe you have a negative sign error
yep
so what is -1/2?
what does that represent?
slope of what
and where?
yes, and where specifically?
x = -2
so we have the slope of the tangent at some point on the curve, what point is this tangent going through?
how did you get that
what is this equation you are using?
so we have the equation f(x) = 2 / x
what is the point on the curve where x = -2 ?
im confused what exactly you are trying to do, why are you multiplying the slope of the tangent by stuff?
so im asking, how can we find a point on the tangent line?
the whole point (erm excuse the pun) of a tangent line is geometrically, it does what? it's meeting with our original curve f(x) with its exact slope at a specific point right?
so here is f(x) = 2 / x (in red) and what the tangent line would look like at x = -2, does that make sense?
what we know so far is the slope of that green line (-1/2) which seems to make sense, that seems correct for its slope
but the important bit is that both the original curve (f(x), the red) and the tangent line (green) share the same point (the blue)
so what is that point?
yep
so now you know a point (-2, -1) and a slope (-1/2) now it's just a matter of using equation from basic algebra to write the equation of a line
find what y?
if you have a point and a slope that describes a unique line
reminder
so y - (-1) = -1/2(x - (-2)) and just simplify in terms of y
youre thinking of y = mx + b which is y intercept equation of a line, but use the point slope if you have slope and some random point
yes, probably simplified version would be y = -1/2 x - 2
whats the problem with that?
graphing in desmos, seems to look correct, the y intercept of the tangent line happens to be -2 yes
i suggest you review this algebra line stuff, calculus is going to eat you up if you aren't quite fluent with this stuff and just algebra basics in general
well, how does instant velocity relate to calculus concepts you've been learning?
have you only learned derivatives in terms of limit so far, you haven't learned any of the shortcuts or anything yet?
can you show the original problem statement, screenshot preferably for this?
ok so uh yeah the problem says position is s = 2t - t^2 whereas you said speed is that
that's why i asked lol
speed and position aren't the same 😄
but yeah part b) you would just do the exact same thing we did for last problem (well just need to find the slope of the tangent line not the whole equation unlike last problem), just different equation, using 2t - t^2 instead of 2/x
but just using this same thing
gotta go but good luck, if you are still having trouble for some reason feel free to open a new help channel if this one becomes inactive
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can u solve this algebraically?
yea
i believe so
or actually
maybe not
not without the lambert w function i don't believe so
@hollow pike Has your question been resolved?
yea so def not lol
i just graphed it
graphically is the way to go then
mar
yupp
how do i multiply sqrt root 10 by 3?
Yes
in simplest radical form
how?
Can I come to you after some time?
dm?
Sure!
its just $3\sqrt{10}$
Mar the Marey
thats the simpliest way to represent it
oh my bad then sorry
wait how would -3/3sqrt root 10 be simplified?
$\frac{-3}{3\sqrt{10}}$
Mar the Marey
is this what your talking about?
what if it was 3/3
Mar the Marey
would it only be sqrt root 10?
Mar the Marey
then do you know what rationalziing is
i dont think its needed
but ik what ur talking
about
multiplying
by sqrt root 10?
i dont think we need that
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maybe its dumb question, but, is this correct
or no
Close
or just uh sinx=0 is x=kpi
It doesn't repeat every π
sin(x) = 0 repeats every pi
okay
sin(x) = -1 doesnt
yeah so its 2kpi
Np
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Usually there are 2 solutions that repeat every 2pi
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For sin(x)=0 those solutions happen to be evenly spaced
For 1,-1 there's only one solution
i see
it's pi/6 + 2kπ and 5pi/6+2kπ
np
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ik what <, > sign mean but i have never seen its application in a equation
<,> meaning a vector?
like less than greater than sign
application means to use yes
ok
in a more mathematical setting, theres applied math
which is just this field of math that i guess "applies" math in daily settings if that makes sense
in terms of greater than and less than sign
in math terms we like to say some "inequality" holds
so x<x+2 would be an inequality
This article lists Wikipedia articles about named mathematical inequalities.
whats meaning of inequality
heres a list of some inequalities
but just think of them as some sort of relationship using < or >
so 1<2 is an inequality
3<2 is an inequality but it isn't true
well not exactly a ratio, but there is ratios involved
uhuh
not sure what you mean by this
i thought like ratios have a relationship of being multiplied with same number to get the actuall number
so they should be considered too
thats why i asked
but nvm that
tell me about what u were saying
Sorry I’m not following this, but basically if you have the inequality 2<3 then it’s also true that 1<3/2
There’s certain things you can do to an inequality like you would with an equation
But just know inequalities are important I guess
like (80+3)/4 -3n/4 <0
and then iin solution -3n/4 was sifter to other side like we do with equal sign
and turned to 3n/4
so i have no idea what logic this follows
cuz this is was my first time seeing it like thiis
so can u tell me how did thiis work
like does transfering work with < sign
I see
So suppose we have a inequality 1<2 notice how adding or subtracting the same number from both sides still give us a true inequality
Think about adding 3n/4 to both sides
What do you mean by transfer
cuz the lecture i was watching said dont do it with positives
i meant like we did with -3n/4
we added both sides right
Well you can subtract things from both sides so yes
I think the issue of doing that is then you get negative on both sides
So consider this
-1<2
If we multiply -1 to both sides
Not ice how it becomes 1<-2
Which is false right
ye
So when we deal with negatives, there’s a rule to flip the inequality sign
I think that’s why the teacher said to not do it the other way perhaps you haven’t convered that yet
well they never started it
it was for a arthmatic progression question
and the info he gave was we transfer it and it becomes positive and dont move positive there
so yea thx
i think i can do more question of that kind now
thank you
I see well I recommend some videos on YouTube
And if you have an library near by or the availability to purchase some math books that might help
Np
ohk
oh hey
incase i run into a situation where i gotta deal with negatives
i should just turn the sign to its opposite right
like < to > or visa versa
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Using one of the quadratic identities to rewrite the equation 1x^{2}-13x+4=0. I know that I reach the right conclusion because I checked the assignments correct answer matched. But did I do it correctly and assigned the right signs in my calculation? Or was I just "lucky" to assign a minus sign twice (which would negate the first wrong sign and result in the final result being correct anyway).
$1x^{2}-13x+4=0\ \ \to\ \ x^{2}+\left(-\frac{13}{2}\right)^{2}-13x=-4\ \ \to\ \ x^{2}+\left(-\frac{13}{2}\right)^{2}-2\cdot1\cdot\frac{13}{2}x=-4+\left(-\frac{13}{2}\right)^{2}\ \ \to\ \ \left(x-\frac{13}{2}\right)^{2}=-\frac{16}{4}+\frac{169}{4}\ \ \to\ \ \ \left(x-\frac{13}{2}\right)^{2}=\frac{153}{4}\ \ \to\ \ \left(x-6.5\right)^{2}=38.25$
DisplayName
$1x^{2}-13x+4=0\ \ \to$
$\ x^{2}+\left(-\frac{13}{2}\right)^{2}-13x=-4\ \ \to$
$x^{2}+\left(-\frac{13}{2}\right)^{2}-2\cdot1\cdot\frac{13}{2}x=-4+\left(-\frac{13}{2}\right)^{2}\ \ \to$
$\left(x-\frac{13}{2}\right)^{2}=-\frac{16}{4}+\frac{169}{4}\ \ \to$
$\left(x-\frac{13}{2}\right)^{2}=-\frac{16}{4}+\frac{169}{4}\ \ \to$
$\left(x-6.5\right)^{2}=38.25$
DisplayName
I wish I knew how to put space vertically betwen the lines, that would help with better overview when looking at it
It's a second degree equation that I must rewrite to one of the quadratic identities. I was given 5 possible solutions, and I did get the right solution.
The right solution is $\ \left(x-6.5\right)^{2}=38.25$
I dont get why there is the 1 in the 1x^2 and why there is a (-13/2)^2 comes from?
DisplayName
Those who made the assignment put the 1 there. But of course 1x = x so you can just ignore it, just like I did. They do that to confuse students Im sure, which is good
Looks correct
(-13/2)^2 comes from a rule about square completion. In the 2nd degree equation ax^2+bx+c=0 you can move c to the left side and get ax^2+bx=-c. And then you add half of b squared on both sides: ax^2+(1/2 * b)^2=-c+(1/2 * b)
So (1/2 * b) is (-13/2)^2
Yea I saw it when i looked closer. It's a bit messy but i see the point
To create a perfect trinomial to make it into (something)^2
What would be a less messy calculation to get the quadratic identity?
$1x^{2}-13x+4=0\ \ \to$
$\medskip$
$\ x^{2}+\left(-\frac{13}{2}\right)^{2}-13x=-4\ \ \to$
$\medskip$
$x^{2}+\left(-\frac{13}{2}\right)^{2}-2\cdot1\cdot\frac{13}{2}x=-4+\left(-\frac{13}{2}\right)^{2}\ \ \to$
$\medskip$
$\left(x-\frac{13}{2}\right)^{2}=-\frac{16}{4}+\frac{169}{4}\ \ \to$
$\medskip$
$\left(x-\frac{13}{2}\right)^{2}=\frac{153}{4}$
$\medskip$
$\left(x-6.5\right)^{2}=38.25$
Found out to make vertical space, Gives a bit better overview I think.
using \medskip
Thanks, Im not a native english speaker so my own languages terms for the math is a bit different. I need to learn the english equivalents too.
For example "x^2 + 6x + 9 is a perfect square trinomial expression, since it can be factored as (x + 3)^2, the square of the binomial (x + 3)."
DisplayName
@peak steeple Has your question been resolved?
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if r is the real part of a strictly complex solution of f, determine an interval I of length 1/2 so that r∈I
@hybrid karma Has your question been resolved?
<@&286206848099549185> i'd like some help thanks :))
What tools can you use to solve this?
@hybrid karma Has your question been resolved?
@hybrid karma Has your question been resolved?
I think he's asking what techniques you can use
i mean idk where to start, that's why i asked for help
i know that there are 2 complex solutions ( conjugates ) and one real solution so i guess if i could find the real solution that would be helpful but i don't know how to find it
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I got this answer as an integrals as no idea why it is wrong
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how do i solve
the f(3) is all i haev so far
I dont know what to do with the f(u) stuff
first try writing $h'(x)$ in terms of $f(x)$, $g(x)$, $g'(x)$, and $f'(x)$
esca (@ with reply)
like this?
hmm are you using product rule? you wanna use chain rule
yep exactly
solve for f'(u)
can you show me how
$f(u) = u^2 - 1$, so $\frac{\dd}{\dd u}u^2 - 1$ is?
esca (@ with reply)
2u
now you can solve for this right
u is just a variable. you just sub in 3 for u in this case
i think your final answer is right but remember youre taking $f'(3)(-1)$, not $f'(-3)$
esca (@ with reply)
wait how come you cant multiply them?
i dont understand how f'(3)(-1) would work
f'(3)(-1) = (2(3))(-1) = -6
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how to do in latek?
,, . \overline B_A
$\overline{B_{A}}$
ekafeman
$\underline B_A$
Ayanokoji
disgusting
do you have reference sheets you can reccomend? I hate having to google and sometimes being unable to find some things
like this one
I see
google detexify
I know a sone
but the rest is just googling
I mean for signs in my courses
well thank you anyway mates
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i made a triangle with the base having 3.5miles and the left angle being 26 degress and the right angle 42 degrees
so the last angle is 118 degrees
<@&286206848099549185>
this is my new question i got the last one wrong
<@&286206848099549185>
let me know if you guys know how to solve this
i cut the last one in half to make a right triangle but the answer was wrong
the angles add up to less than 180 if i cut it in half
do i use low of cosines instead?
law
but i have to find the height so that's why i thought i would cut it in half
Try to draw a diagram
i drew a triangle with the base being 3.2 and the bottom left angle is 26 and the bottom right angle was 39
yeah that's correct
so what's the third angle going to be
so i thought the last angle would be 115
You will see that the man will create a right triangle with the balloon and the woman will also create a right triangle with the balloon
ok good
so do i make it a right triangle after?
okay so i split it in half and half of 115 is 57.5
but 26+90+57.5 is 173.5 which is less than 180
so the answer wont be correct
am i supposed to split it differently
cause the answer wont make sense if the right triangle is less thatn 180 degrees right
I think you are complicated thing
if we know two angles
then we can find the third angle
right so found the 3rd angle it was 115 degrees
And then using law of sine
you can find two remaining sides of a triangle
If you draw a straight line from the balloon to the base of the triangle, it will create a right triangle, and from this, I think you can solve it using trigonometry.
okay let me try that first
okay so i did the problem and the let me send a picture of my work
the hypotnuse is more than the bottom if i make it into a right triangle tho
i mean hypotnuese is less sorry
@dusky ocean
Where does 1.75 come from
i divided 3.5 in half
Ok I understand your mistake
You have the angle which is 39 and you have the hypotenuse (m) so you can figure the distance from the balloon to the ground
It is not simply divide 3.5 by half
yeah because the balloon is not in the middle
yes
it's closer to the person whose angle is 39
law of sine or trigonometry
you don't need it for the height but it's easy
ohh so i can use the sin of 39 degrees with the height and sine of 90 with the hypotnuse right?
so i can just get the height i dont need the base
it says the answer is wrong tho its not 5625
so i have to find the base still?
or you can use the definition of sine
LOLL ur good
okay so i multiplied sin(39) but 1.6929
and then divided it by sin90 which is just one
and the multiples but 5280 cause if 5280 ft per mile
i got 5625 but it says my answer is wrong 😭
idk what to do LOL
let me check aha
Have you converted it to feet?
ya i did
okay so 5143 ft
Ok. This type of problem always has something to do with right triangle😂
Yw. it also helps cuz I have exams soon 😭
LOL i just finished im doing a summer class to get a credit done
it goes faster than the ones over the year so its harder to go so fast 💀
but thanks anyways good luck on ur exams
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My first thought was to find $u_{n+1}$ in terms of $n$
ƒ(Why am. I here)=I don't Know
which would be $n-1 + \frac{1}{n-1}$
ƒ(Why am. I here)=I don't Know
$\frac{n-1 + \frac{1}{n-1}}{2} \leq \sqrt \frac{{(n-1)^2 + \frac{1}{(n-1)^2}}{2}$
I guess AM<QM isn't the way to go here?
just yes/no please
wait, is it just sufficent to show $n-1 + \frac{1}{n-1} \leq \frac{3 \sqrt{n}}{2}$
ƒ(Why am. I here)=I don't Know
like just solving this inequality is sufficent ?
You take u_n-1=n-1?
$u_n = n-1 + \frac{1}{n-1}$
ƒ(Why am. I here)=I don't Know
but then u_1 is undefined
for all n>1
since $u_1=1-1+\frac1{1-1}=\frac10$
Flappie
aha
You got the sequence by putting terms or what ?
$u_2=2-1+\frac1{2-1}=1+\frac11=2$
oh, vm
Flappie
$u_3= 2 +\frac{1}{2}$
ƒ(Why am. I here)=I don't Know
ƒ(Why am. I here)=I don't Know
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if for all vector v in subspace V: <Tv, v> = <Sv,v>
does T=S?
yeah i just got one
if u take S as the transpose of T
when T is non symmetric
Yeah that works
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How would 50 be wrong. Is it suppose to be concave up and concave down inflection point?
To put it more clearly, an inflection point is where it goes from concave to convex or vice versa
Does it seem to you like that is the case at x=50?
Noo would it be 500? Since it's starting to go back up
I wouldn't say the inflection point is at x=500 but at least you seem to understand the reasoning behind it now
That is in fact how you spot in inflection point
Assuming we're going from left to right, before it was dipping further and further down and then it started to aim further and further up a little bit
Were that switch occurs (or the reverse), we have an inflection point
Personally I'd say the inflection point is before x=500
just at a glance
@midnight haven Does that all make sense?
Yes thank you!! This is making more sense I think I just need to look at more graphs and quiz myself. Thank you!!!
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Can someone walk me through this simplification process? y, w, and s are all bitstrings.
Can you explain what the operations do?
i believe the + with a circle is bitwise addition
Circled plus is xor addition I assume
Dot is dot product with xor reduction?
What is exponentiation?
Is this over GF(256)?
yes the dot is the dot product
the circle with the plus is the xor symbol
y, w, and s all have the same size
and the exponentiation is just normal exponentiation
Ok, then this is pretty straightforward
First line to the second line is distribution in the exponent, then reverse distribution outside of it
i think the two main things to realise are that $a \cdot \left(b \oplus c\right)) = \left(a \cdot b\right) \oplus \left(a \cdot c\right)$ because $\mathbb{Z}_2$ is a group so has the distributive property
and also that $\left(-1\right)^{a \oplus b} = \left(-1\right)^a \left(-1\right)^b$
Acman
okay so because only the parity matters here we can do the reverse distrubution
right?
(-1)^(y.w) + (-1)^(y.w + y.s)
(-1)^(y.w) + (-1)^(y.w) * (-1)^(y.s)
Then factor out the (-1)^(y.w)
field*
okay so first line to second line works because how again?
I can factor out $(-1)^y$ easily
but how does $w$ also get factored out?
do you understand why $\left(-1\right)^{y\cdot\left(w \oplus s}\right)} = \left(-1\right)^{y \cdot w} \left(-1\right)^{y \cdot s}$
I understand this yes
Acman
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oh okay I see now how that works
actually wait I need to process this a little more
so the xor will be 0 if they are the same and then the dot product will sum the corresponding terms multiplied
oh I see
so if both are 0 then it will be (-1)^0 * -(1)^0 which is 1
and if both are 1 it will be(-1)^1 * (-1)^1 which is 1
so basically nothing happens
does that line of reasoning make sense?
if that makes sense, then I get how the first line goes to the second line
say $a, b, c \in \mathrm{Z}2^n$ that is $a = \left(a_1, \dots, a_n\right)$ with $a_i \in \left{0, 1\right}$ and similar for b and c \
addition in $\mathrm{Z}2$ (explicitly written as $+2$ - though here ill continuet to use $\oplus$) works $\mathrm{mod} , 2$ so $1 + 1 = 0$, multiplication works like normal
\begin{align*}
a \cdot \left(b \oplus c\right) &= \begin{bmatrix} a_1 \ \vdots \ a_n \end{bmatrix} \dot \begin{bmatrix} b_1 \oplus c_1 \ \vdots \ b_n \oplus c_n \end{bmatrix} \
&= \sum{i=1}^n a_i \cdot \left(b_i \oplus c_i\right) \
&= \sum{i=1}^n \left(a_i \cdot b_i\right) \oplus \left(a_i \cdot c_i\right) \
&= \sum{i=1}^n \left(a_i \cdot b_i\right) \oplus \sum_{i=1}^n \left(a_i \cdot c_i\right) \
&= \begin{bmatrix} a_1 \ \vdots \ a_n \end{bmatrix} \dot \begin{bmatrix} b_1 \ \vdots \ b_n \end{bmatrix} \oplus \begin{bmatrix} a_1 \ \vdots \ a_n \end{bmatrix} \dot \begin{bmatrix} c_1 \ \vdots \ c_n \end{bmatrix} \
&= \left(a \cdot b\right) \oplus \left(a \cdot c\right)
\end{align*}
Acman
LaTeX source sent via direct message.
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\mathaccentV ...blethree \frozen@everymath {}$#5$}
\macc@tmp \ifnum \macc@dep...
l.58 \end{align*}
I've deleted a group-closing symbol because it seems to be
spurious, as in `$x}$'. But perhaps the } is legitimate and
you forgot something else, as in `\hbox{$x}'. In such cases
the way to recover is to insert both the forgotten and the
deleted material, e.g., by typing `I$}'.```
okay I understand now
the first step to the second step
but then from the second to the third step, $(-1)^{y \cdot w}$ just disappears
Decoway
$\left|ab\right| = \left|a\right| \left|b\right|$
Acman
and also $\left|\left(-1\right)^n\right| = 1$
Acman
okay that makes sense
because $\left(-1\right)^n$ is either -1 or 1, either of which has absolute value 1
Acman
right
and then step 3 to 4 is trivial
okay!
I got it!
thank you so much
you've helped me twice today 🙏
nice!!
happy to !

all the best
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i tried solving this and failed, can anyone help?
I mean you dont even need the inner product structure here
yeah i figured that but it was given in the question for a follow up question
can you give a few equivalent conditions for a map to be diagonalizable
that there exists a basis that the matrix represnting the map is diagonal
is there something i'm missing?
there is a nice one with the minimal polynomial
of course you can also just find a matrix representation of the map and then find eigenvalues and eigenvectors of that
i can't recall something like that
that is unfortunate
then do that
Never heard of the minimal polynomial to be split with multiplicities 1?
isn't that the charestersic polynomial?
No, the minimal polynomial
alright

