#help-43

1 messages · Page 62 of 1

cursive harbor
#

,tex $\sin^3(x) + \cos^3(x) = 1$

boreal girderBOT
#

Xavier 🌺

cursive harbor
#

Well are you familiar with the factorization of a³ + b³

thick shore
#

yeah

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i already did that

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but im stuck after replacing the squares with 1

dawn briar
#

How do you make a canonical form of a matrix?

cursive harbor
#

What do you have currenrly

bleak dock
cursive harbor
compact pewterBOT
cursive harbor
thick shore
#

,tex $(sinx+cosx)(1−sinxcosx)=1$

cursive harbor
#

Well

boreal girderBOT
#

JustBrutal
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

cursive harbor
#

There's obvious answers here without any further simplification

thick shore
#

yeha but how do u prove with algebra that this equation leads to sinx=1 and cosx=0

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or sinx=0 and cosx=1

thick shore
cursive harbor
#

Are you familiar with differentiation

tired bear
#

maximum value the function $f(x) = \sin^3(x) + \cos^3(x)$ can obtain

boreal girderBOT
thick shore
#

i dont study maths in eng so no

cursive harbor
#

Derivatives?

thick shore
#

nope

#

still havent reached that lvl

cursive harbor
#

I see

thick shore
#

any way of directly proving it?

thick shore
cursive harbor
#

I'm sure there is, but I'm also very bad at trig

thick shore
#

oh okay

cursive harbor
#

So I'm gonna let a more capable helper help you

thick shore
#

<@&286206848099549185>

thorny heath
#

where you stuck?

thick shore
#

,tex $\sin^3(x) + \cos^3(x) = 1$

boreal girderBOT
#

JustBrutal

thick shore
#

@thorny heath find the sols without derivatives

thorny heath
#

derivatives?

#

what is original question?

thick shore
#

bruh

thorny heath
#

whole question

thick shore
#

prove this

thorny heath
#

k

thick shore
#

<@&286206848099549185>

thorny heath
#

hmm..

#

sin(x) max = cos(x) max =1

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you can say one of the terms should be 1,

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or put sinx + cosx = t

thorny heath
#

define t : $-\sqrt{2}<=t<=\sqrt{2}$

boreal girderBOT
#

heisenberg

tired bear
#

oh wait oh boy

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i got a funny one

#

$\sin^3(x) + \cos^3(x) = 1 = \sin^2(x) + \cos^2(x)$

boreal girderBOT
tired bear
#

$\implies \sin^2(x) \cdot (\sin(x) - 1) + \cos^2(x) \cdot (\cos(x) - 1) = 0$

boreal girderBOT
tired bear
#

can you see where this is going

thorny heath
#

ic

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i dont see

tired bear
#

$\implies (1 - \cos(x))(1 + \cos(x))(\sin(x) - 1) + (1 - \sin(x))(1 + \sin(x))(\cos(x) - 1) = 0$

boreal girderBOT
thorny heath
bleak dock
#

.close

compact pewterBOT
#
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compact pewterBOT
#
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icy nymph
#

so this is the question
$\begin{tikzpicture}
\draw[->,ultra thick] (-4,0)--(4,0) node[right]{$x$};
\draw[->,ultra thick] (0,-4)--(0,4) node[above]{$y$};
\draw[domain=-1.6:1.6, smooth, samples=200, very thick, <->] plot({\x},{(\x*\x - 1)^3});

\end{tikzpicture}$

boreal girderBOT
#

Flatus

icy nymph
#

if the question asks when this graph is parallel to the x-axis,

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is it 1 or 3?

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-# ||or is it just very poorly worded||

runic creek
runic creek
icy nymph
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oh shi

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yeah

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the tangent i mean

runic creek
#

If it's the tangent then 0 is also included

runic creek
icy nymph
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when the tangent to the graph is parallel to the x-axis

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implying
when is the gradient = 0

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so would those stationary points lying at y=0 count as "parallel to the x-axis"?

#

@runic creek

icy nymph
runic creek
#

Yes

icy nymph
#

.close

compact pewterBOT
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compact pewterBOT
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pastel ice
compact pewterBOT
pastel ice
#

is it valid to confirm the integral converges first

open girder
pastel ice
#

then say since the function is odd splitting the integral up from -infinity to 0 and from 0 to +infinity both integrals will then be equal and will cancel each other out giving you 0

open girder
#

Yes

pastel ice
#

alright tyty

#

.close

compact pewterBOT
#
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open girder
compact pewterBOT
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hollow kettle
#

what. do i do. how do i plot (exponential functions)

hollow kettle
#

i had MASSIVE brain fog and was somehow the most bored i have been in my math class today so i think half the info went through my ears

rotund sphinx
#

Ex. If $x=1$, then $y=3^1-5=3-5=-2$, so you'd plot the point $(1,-2)$

boreal girderBOT
#

Civil Service Pigeon

compact pewterBOT
#

@hollow kettle Has your question been resolved?

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wary mulch
compact pewterBOT
wary mulch
#

why did he add 72?

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woudnt that be double counting

upper bane
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no

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the table clearly separates all four categories. there's no risk of double counting here

wary mulch
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whats with the double counting in the additional rule

upper bane
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wdym? there is no such thing, esp. not with the setup in this pic

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there is no such thing in this pic

#

mb

kind viper
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here is what it would look like if you overcounted:

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total guilty = 11+72 = 83
total who did it = 72+9 = 81
and then you would add 83+81

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but then the ones who are guilty AND did it (72) get counted twice

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also, addition rule, no -al

compact pewterBOT
#

@wary mulch Has your question been resolved?

compact pewterBOT
#
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compact pewterBOT
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high shadow
#

guys when doing functions table, what happens if i get an ERROR?

high shadow
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(the equation was divided by 0)

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what plot do i do?

cursive harbor
#

Well the exact answer depends on what exactly you are plotting

#

!original please

compact pewterBOT
#

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.

high shadow
#

what...

cursive harbor
#

The plot you do depends on what exactly your function looks like

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More specifically what exactly was divided by zero

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Just show the original question please

high shadow
#

fine shawty

past ginkgo
#

fine shawty

high shadow
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number 9.

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Error at f(-1)

cursive harbor
#

Let's think about what happens when x is close to -1

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Let's say -0.9 for example

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Since you're using a calculator anyway

high shadow
#

idk how to edit the table

upper bane
#

you can do it manually

high shadow
#

hoe

#

how

upper bane
#

type $\frac{2}{(-0.9)+1}$

boreal girderBOT
#

Hanako(x, y); ∂(fox)/∂x

high shadow
#

ugh so i have to delete it..

upper bane
#

if the calculator gives you lemons, find ways to work around it

high shadow
#

okay then

sullen merlin
# high shadow fine shawty

Please don't use nicknames like "shawty", or for example "babe", etc to refer to people you don't know, it can make people uncomfortable

high shadow
#

that was a joke..

sullen merlin
#

yeah but jokes can make ppl uncomfortable, the important thing is to just avoid doing it in the future

high shadow
#

fine

#

.close

compact pewterBOT
#
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compact pewterBOT
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dull heron
#

Hello everyone! I had an exam today and I am not sure if I got a question right and it’s really bugging me that I can’t remember/answer it correctly. If I am not mistaken we were required to find mean squared error MLE theta.hat of theta for the Bernoulli distribution. I wrote theta(1-theta). Was that correct? Thank you so much in advance

compact pewterBOT
#

@dull heron Has your question been resolved?

dull heron
#

No

pseudo rapids
#

could you first find the Likelihood fnction of the bernoulli distribution?

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please open ur own channel king

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This ones tamaras

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close

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not 1.1

wheat pasture
#

It was a one hour mute for trolling in someone else's help channel catokay

dull heron
pseudo rapids
#

correct answer is your answer over n

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do you understand why?

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or are you too tired

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which is fair

dull heron
#

It was 20 statistics questions in 90 minutes

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I am really exhausted but thank you very much

#

.close

compact pewterBOT
#
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compact pewterBOT
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compact pewterBOT
#
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cursive warren
#

.close

drifting flax
compact pewterBOT
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peak stratus
compact pewterBOT
peak stratus
#

is it correct

keen granite
#

trying to sketch f'(x)?

peak stratus
#

yep

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i didnt add the coordinates

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im gonna guess its not correct

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?

thorny urchin
#

seems ok

peak stratus
#

all im missing is the coords right?

#

which was intentional btw

thorny urchin
#

yes

peak stratus
#

ok thanks

#

.close

compact pewterBOT
#
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compact pewterBOT
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woven prairie
compact pewterBOT
woven prairie
#

Can someone help with the second one

#

Would it converg or diverge ans why

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And

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Also this is in french sorry

lusty sequoia
woven prairie
gilded dirge
#

1/(n+1)^(1+(1/n^2)) Is that correct

woven prairie
gilded dirge
#

It seems to be a geometric series

woven prairie
#

Nah
For me it looks like a reiman thing

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Smthn like 1/n^æ

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Cuz like
n+1 is the same as n when n approches infinity

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So it really depends on weather u call 1+1/n² > 1 or u just say it is equal to 1 when n approches infinity

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Im not sure about it

gilded dirge
#

Maybe try replacing the sigma with an integral

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Integrate over n to get the value

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If it keeps increasing, it will diverge to infinity

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or else it will converge on a number

compact pewterBOT
#

@woven prairie Has your question been resolved?

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open lotus
#

i need help on part a. isnt a vertical tangent line an undefined slope?

kind crane
#

Yes

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do you have an equation for dy/dx

open lotus
#

i should be taking a look at (dy/dt)/(dx/dt) right

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oop

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there it is

open lotus
#

and put y3 = y2/y1

kind crane
#

Idk what y1 and y2 are supposed to be

kind crane
#

No idea what your calculator model is doing

open lotus
open lotus
kind crane
#

You don't need to graph at all to do a)

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Graphing wouldn't give you an exact answer anyway

open lotus
#

alright

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but what about dy/dx? i have it stored in the calculator as Y3 but how do i set it equal to an undefined value?

kind crane
#

finite / 0 = vertical tangent

open lotus
#

from t=0 to t=1.5 there’s a point where the tangent line of the particle is ?/0

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how should i set that up in my calculator?

kind crane
#

Use math, not calculator

open lotus
#

the first section of the ap frq is always calculator active

kind crane
#

What's the denominator equal to?

distant path
#

.

kind crane
open lotus
#

and sine of 0 should be 0

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at t = 0 and pi, dy/dt is 0

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and then dx/dt should equal a finite number, and if we plug t = 0 into it, we should get a real finite number

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wait i got it

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at t=0, the line tangent to the particle is vertical

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we don’t use pi bc 3.14 is not in the 0 to 1.5 interval

kind crane
#

You messed up logic somewhere

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write down explicitly what function is the denominator

open lotus
#

oh my days i did dx/dy instead

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dx/dt has to equal 0 in between 0 and 1.5

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while dy/dt has to be finite

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theres two times dx/dt is equal to zero

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and where dy/dt is not zero

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t = 1.145

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and at t = 1.253

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that blue line represents dx/dt while the red one is dy/dt

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at both points when the blue line is at 0, dy/dt on that same t is a real nonzero value

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at these two points dy is a real number while dx is 0, satisfying the conditions that dy/dx needs to be equal to finite/0

kind crane
#

,calc log(pi)

boreal girderBOT
#

Result:

1.1447298858494
kind crane
#

,calc sqrt(pi/2)

boreal girderBOT
#

Result:

1.2533141373155
kind crane
#

Both look right

open lotus
#

that’s crazy

#

wait that’s so cool

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i take it i got the right answer, so im going to sleep

#

tyy

#

.close

compact pewterBOT
#
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abstract agate
#

why is this matrix not diagnolizable?

compact pewterBOT
rigid perch
#

what do you get for the eigenvalues and eigenvectors?

kind viper
compact pewterBOT
#

@abstract agate Has your question been resolved?

compact pewterBOT
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wintry knot
#

here, we are trying to find out if the conclusions of both I1 and I2 are true or not by making all the premises true and the conclusions false. in I2, we took ~R as true so R would be false, then does ~C not have two possible values (both true and false)? why did we only take one possible value (true), here?

wintry knot
#

because taking ~C as false would make C true and hence I2 would be valid, right?

#

please ping if responding

compact pewterBOT
#

@wintry knot Has your question been resolved?

wintry knot
#

in this example as well, for (b), we took ~C as true so for the first premise (C -> ~E), does E, again, not have two choices?

woeful schooner
#

Citing wikipedia

In logic, specifically in deductive reasoning, an argument is valid if and only if it takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false.

wintry knot
#

okay so we kinda always take the case where an argument can be invalid?

woeful schooner
#
To give you a slightly more digestible peice of data which is easier to understand
$$x + 3 = 4 \implies x = 1$$
Look at the implication here, given that the first statement ($x + 3 = 4$) is true the consequence ($x = 1$) can not be false.
boreal girderBOT
#

@woeful schooner

wintry knot
#

i get your point but

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well, all right, makes sense

#

thank you!

woeful schooner
#

You're welcome :)

thorny heath
woeful schooner
#

!done

compact pewterBOT
#

If you are done with this channel, please mark your problem as solved by typing .close

wintry knot
#

but well yeah, it makes sense

#

anyway, thanks again

#

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safe raptor
#

how to solve this integral
I have to use U sub

compact pewterBOT
tired bear
#

$\int 2^u \cdot \frac{3}{2} du$

boreal girderBOT
tired bear
#

how did that become $\int \frac{6^u}{2} du$

boreal girderBOT
safe raptor
#

can i not do 6^2/2 which would be 3^u?

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so i can take 3/2 out of integral but how do i take the integral of 2^u du?

tired bear
#

did you learn exponent laws clearly

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try with any u

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you cannot do that

tired bear
#

$\int{a^x dx} = \frac{a^x}{ln(a)} + C$

boreal girderBOT
tired bear
#

a is a constant

safe raptor
#

how do you get to that or is it just something I just have to know to solve this integral?

tired bear
boreal girderBOT
tired bear
#

you can use some method like logarithmic differentiation to prove this

tired bear
#

but its mostly a common integral

safe raptor
#

i didnt have differentials yet

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but i will chekc this out

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so once i use this i just resub back to X?

#

thank you

#

.close

compact pewterBOT
#
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tired bear
compact pewterBOT
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young tinsel
#

What is the area, in square units, of the region enclosed by y= |x-20| and y=10?

potent berry
#

!status

compact pewterBOT
#
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
young tinsel
# junior saddle What have you tried?

I saw the solution to the problem, and it said something about the function having a vertex at (20,0 ) and that it created an isosceles triangle, but i have no idea where they got any of that info from

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i know that x=30 or 10 but that's it

junior saddle
#

Or try calculating the intersection point.

daring axle
#

translating 20 units to the right gets you to (20,0)

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since abs(x -20) means translating abs(x) 20 units to the right

young tinsel
#

how does the absolute value of x have a vertex at the origin

daring axle
#

,w graph |x|

daring axle
#

those are two lines

#

namely, y = -x and y = x

#

plotted for y >= 0

#

the two lines intersect at (0,0)

young tinsel
#

oh ok i understand it now

#

thanks

#

.close

compact pewterBOT
#
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compact pewterBOT
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robust flicker
#

how do i solve this? i am unable to approach it

short ferry
#

have u drawn a diagram?

robust flicker
#

yes

#

a circle with the fence as a tangent

random mica
#

if the horse travels x km along the circle, what angle has it made to the centre of the circle

short ferry
#

so ur diagram looks like this?

robust flicker
#

yes

robust flicker
#

some guy told me to find the speed of shadow as a function of time

#

but i dont get how to do that

random mica
#

i said x km

#

will the horse make the same angle for any x km?

robust flicker
#

uhh

#

if it

#

im getting 10T/pi

random mica
#

it should be x/r

#

where r is the radius in km

robust flicker
#

if

#

wait

#

how did u get x/r?

random mica
#

what is the definition of angles in radians

robust flicker
#

r theta = arc length

#

by this?

random mica
#

yes

#

so theta = x/r

robust flicker
#

ok so what next

robust flicker
random mica
#

now, from our diagram, how can we get the distance travelled by the shadow from this

robust flicker
#

hiow?

random mica
#

pull up the diagram

robust flicker
#

ye

random mica
#

(hint: trigonometry)

robust flicker
#

lets say distance covered by the shadow is y

#

so by trigno tan(x/r) = y/r

random mica
#

yes

#

great

robust flicker
#

then?

random mica
#

so distance travelled by the shadow = r * tan (x/r)

robust flicker
#

why did we multiply r

#

oh ye

#

mb

random mica
#

now take the time derivative of both sides

robust flicker
#

k

random mica
#

(r is constant and x changes with time

robust flicker
#

im getting

#

2/r square

random mica
#

how?

robust flicker
#

tan x derivative is sec square x right

random mica
#

yeah

robust flicker
#

so 1/r is constant anyway

#

tan(x/r) to 1/r(sec square x/r)

#

and 1/r from before too

#

sec square x/r whole by r square

random mica
#

close

#

$\frac{dy}{dt} = \frac{1}{r} \sec^2\left(\frac{x}{r}\right) \frac{dx}{dt}$

#

dx/dt is left

robust flicker
#

oh

boreal girderBOT
#

CherryMan

random mica
#

(chain rule)

robust flicker
#

i forgor abt that

#

ye

random mica
#

so do we know x

robust flicker
#

uhh

#

we know speed

#

speed times time is x

#

2ot

random mica
#

but read the question carefully

#

we are explicitly given everything

#

they said the horse covers 1/8 of the circle

robust flicker
#

1/8?

#

oye

random mica
#

so 1/8 * 2pi r

robust flicker
#

ye

robust flicker
#

ye

random mica
#

and dx /dt is 20 as you said

#

so can you find dy/dt

robust flicker
#

what abt the 1/r

#

thats left

random mica
#

just put everything in

#

see what happens

#

(all r's cancel out)

robust flicker
#

ohhhh

#

ye i got the ans

#

tysm

random mica
#

welcome

robust flicker
#

.close

compact pewterBOT
#
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gray crest
#

Kinda stuck? Don't know where to go from here, my brain just stopped

primal drift
primal drift
#

Wait

gray crest
#

I am a highschool student i don't know what a tan inversa omega is

primal drift
#

And you can solve integration...

gray crest
#

😭

#

you got any simpler solutions man?

primal drift
gray crest
#

okay let me try that

primal drift
gray crest
gray crest
primal drift
#

Wait

gray crest
gray crest
primal drift
#

Is it visible?

gray crest
#

not really

primal drift
gray crest
#

okay can you wait a minute and check if i am right?

primal drift
#

Ok

gray crest
#

Like this right?

#

and then I just change everything back with disrespect to x

primal drift
gray crest
#

LETS GOO

gray crest
#

i kept searching and found some stuff called tanh^-1 or smth

primal drift
#

Ok, welcome nvm

gray crest
#

Thank youu

#

.close

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#
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azure edge
#

struggling with an rref algorithm, this matrix ends up as an identity matrix, but if I parallel its operations onto an identity matrix I don't get its inverse

azure edge
#

I think it's a math issue not a programming bug

#

bc I wrote this memory, where to get ref I

{go through each row, if nonzero element, choose it as your next pivot row, swap it with the row beneath your previous pivot row, multiply it so the lead is 1, weighted sum it on every row below to make every entry below the pivot 0}```
#

then to get rref

{find the leading nonzero element, weighted sum this row on every row above so every element above the lead is 0}```
#

the error I get is that after this is all said and done, A * (my calculated A inverse, where I do parallel rref on A and identity matrix), = not identity matrix

#

and yes the matrix is invertible

kind crane
#

can you print your matrix at every operation to debug

azure edge
#

probably, let me check

#

lambda functions sometimes resist the use of external variables

#

(colored text bc my prints are extremely long, and I need an easy way to find which one I care about)

#

I show the output matrices from each operation, the input is the matrix directly above (all operations shown)

hushed magnet
#

(havent checked your code)

#

say the entry is 1e-12, thats nonzero but certainly should never be your pivot

azure edge
#

yup that is in fact what I was just checking

#

specifically the third row, matrix 1E-40 or whatnot

#

I do have built in functions to cancel out numbers when summing (a, -a) (I check if the ratio is close enough to -1)

#

istg

#

that was it

#

thank you! I have been tearing my hair out over this.

#

I was calling a function that does not check when doing a += b if (a ~= -b)

kind crane
#

i love when RREF makes me get numbers on the order of 10^45

azure edge
#

it multiplied by 10^-60 and all was well

#

I also do get numbers also on the order of 10E45

#

because sometimes my newton raphson diverges horribly

#

and I have to calculate e^(10^15)

#

or, sometimes, more reasonably, just e^150 or so

kind crane
#

wow. dafuq is your machine epsilon

azure edge
#

amusingly, even with these terrible errors, I can still do euler stepping + newton raphson for simulation purposes so long as I add a dampening factor into NR and limit the maximum change between NR iterations to like norm ≤ 0.1

azure edge
kind crane
#

how do you even have 10^-60 then

#

or was it just symbolic

azure edge
#

the range of a double precision float is 1E-308 to 1E308 iirc

#

the precision is 15-17 orders of magnitude

#

doubles do well with multiplication that doesn't need to be exactly correct

kind crane
#

oh nice

azure edge
#

so if I multiply the whole row with 1E40, the exponent in the double just gets + 40 (in binary), that's not a problem

#

oh well thanks again!!

#

this has been haunting me

#

.close

compact pewterBOT
#
Channel closed

Closed by @azure edge

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kind crane
#

TIL

#

ty too!

compact pewterBOT
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chrome quail
#

simultaneous elimination method

compact pewterBOT
slate sand
#

What have you tried

quiet sentinel
#

you want to make one term the same in each equation so it can be eliminated through subtraction

#

in this case that is already done

chrome quail
#

ok

#

i did equation 1 - equation 2

#

-2x + 0y = 8

quiet sentinel
#

you forgot the constant is negative

#

14-22=-8

chrome quail
#

yea

#

forgor

#

i got 4

#

as the x

drifting flax
#

Well on the paper it says x =

#

Don't know where the 4 went

#

But notice your system of equations has two unknowns, x and y

#

You got the x

#

You need the y still

chrome quail
#

i got -3y

lusty sequoia
#

plug that in to 7x + 2y = 22

#

then
28 + 2y = 22
2y = -6
y = -3

#

if thats what u meant

drifting flax
#

Ah I see

chrome quail
#

well i plugged it into equation 1 instead

lusty sequoia
#

yeah either works

#

so the solution is (4, -3)

chrome quail
#

ye

#

how do i do this

#

a cup and a soacer cost $3.15 together. a cup and 2 soacers cost $4.50. Find the cost of a cup and of a soacer

lusty sequoia
#

*two equations

chrome quail
#

c + s = $3.15

#

c + 2s = $4.50

lusty sequoia
#

yeah

#

so now you can solve with elimination

#

you get
0c + s = $1.35
s = $1.35

c + $1.35 = $3.15
c = $1.80

drifting flax
#

While making them actually do the steps or give their approach etc.

lusty sequoia
#

you have
c + s = $3.15
c + 2s = $4.50

and you can subtract the first equation from the second to cancel out c

chrome quail
#

wym by cancel out tho

lusty sequoia
#

like when you subtract c + s = 3.15 from c + 2s = 4.50 you get

(c - c) + (2s - s) = (4.50 - 3.15)
s = 1.35

#

you are "eliminating" c since you subtract c in the first equation from c in the second equation

chrome quail
#

ok

#

so

#

eq 2 - eq 1 gives u 1.35

#

thats for s

#

@lusty sequoia

compact pewterBOT
#

@chrome quail Has your question been resolved?

compact pewterBOT
#

@chrome quail Has your question been resolved?

compact pewterBOT
#

@chrome quail Has your question been resolved?

#
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novel wagon
#

where would I plot this?

compact pewterBOT
grizzled ember
#

On the complex plane.

novel wagon
#

not sure how to figure it out

grizzled ember
#

Do you have any formulas which relate the modulus and the argument of a complex number to the x +iy form?

#

hint: e

spark folio
#

other way you could do that is you already know that the magnitude is 4, so it is gonna lie on a circle of radius 4, which should be easy enough to plot

near crown
#

Idk if that's the problem if they're asking how to plot

spark folio
#

and from there you figure out the angle and how to place that in the plane

viscid canopy
#

consider searching polar coordinates

grizzled ember
near crown
#

No it isn't

spark folio
#

same end result does not mean same order of steps

novel wagon
grizzled ember
#

I think to use the perspective that z lies on a circle of some radius is implicitly using euler

near crown
#

Id recommend following Baxtep's comment

#

What fraction of a circle is the angle?

spark folio
novel wagon
grizzled ember
#

Note that without the multiplication between complex numbers, the structure is identical to vectors in R^2. If you've done linear algebra then this is just finding the tail of a vector with this magnitude and angle

lusty sequoia
#

you are overcomplicating it

grizzled ember
#

I don't know what level this guy is at.

near crown
#

Look at the problem then

grizzled ember
#

I didn't come across complex numbers in precalc so i just assumed it was university

near crown
#

Do you think they've done linear algebra?

grizzled ember
#

Uh, yes.

lusty sequoia
#

@novel wagon but yes the intuition is thinking about it as in polar coordinates, where the point lies on a circle of radius 4 and at the angle 5pi/3

#

and to find that coordinate you use trigonomtery to get (r cos(theta), r sin(theta)) = (4cos(5pi/3), 4sin(5pi/3))

lusty sequoia
grizzled ember
#

If you have this information (modulus and angle) and still don't know what to do, then it indicates to me that they just don't know the definitions.

novel wagon
lusty sequoia
#

yeah (2, -2sqrt(3))

novel wagon
#

so convert to decimal and then just plot

#

ah okay

compact pewterBOT
#

@novel wagon Has your question been resolved?

novel wagon
#

.close

compact pewterBOT
#
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compact pewterBOT
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brave tusk
#

i dont understand Polynomial long division

compact pewterBOT
brave tusk
#

like here is a question for it

#

(2a^2-4a-8)÷(a + 1)

#

<@&286206848099549185>

chilly basalt
#

I have two approaches for you

#

One fulfills your need, long division

#

the other requires a bit prerequisite knowledge

#

Let's begin with the former, do you have a paper and a pen with you?

#

or a pad

#

@brave tusk

chilly basalt
compact pewterBOT
# brave tusk <@&286206848099549185>

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.

brave tusk
chilly basalt
#

and write down what I write

brave tusk
#

done

chilly basalt
#

Right, what the value of 2a^2 divided by a?

chilly basalt
#

correct, right it above 2a^2 and the line

brave tusk
#

Like this?

chilly basalt
#

let's speed up the process, what's 2a times a
Write it below 2a^2

#

and 2a times 1
write it below -4a

chilly basalt
#

Alright, finish it and share the progress after that

brave tusk
chilly basalt
#

excellent

#

now repeat the process

brave tusk
#

Wait

#

No

#

-6

chilly basalt
#

-6a divided by a

brave tusk
chilly basalt
#

yep

#

Alright, you know the drill

brave tusk
#

Whats the last step

chilly basalt
brave tusk
chilly basalt
#

there is a small mistake in your last step

brave tusk
#

yeaaa

#

i see it

chilly basalt
#

,calc (-8)-(-6)

boreal girderBOT
#

Result:

-2
brave tusk
#

i should do -8+6

brave tusk
chilly basalt
#

that's everything

#

time to collect the result

#

2a-6 is the quotient

#

-2 is the remainder

brave tusk
#

alright thanks man

chilly basalt
#

anything else?

#

I can provide you an alternative

#

a slightly more advanced approach

brave tusk
chilly basalt
boreal girderBOT
#

VerifiedCrank

chilly basalt
#

We can write their relationship as the following
$8 = 3\times 2 + 2$

boreal girderBOT
#

VerifiedCrank

chilly basalt
#

Do you agree so far?

brave tusk
chilly basalt
#

So we got the equation\
$2a^2-4a-8 = (a+1)Q + R$ where Q is the quotient and R is the remainder

boreal girderBOT
#

VerifiedCrank

twilit schooner
#

I think I should mention that you don't need to think of "polynomial divison" as some magical algorithm, it's just algebra:
(2a^2-4a-8) / (a + 1) = (2a(a - 2) - 8) / (a + 1) = (2a(a+1-1-2) - 8) / (a+1) = (2a(a+1) + 2a(-3) - 8) / (a+1) = 2a + (-6a - 8) / (a+1) = 2a + (-6(a + 1) - 2) / (a+1) = (2a - 6) - 2/(a+1)

... If I didn't screw up algebra

chilly basalt
#

Let's plug in a = -1 to find out the remainder

brave tusk
#

alright

chilly basalt
#

$-2 = (0)$Q + R

boreal girderBOT
#

VerifiedCrank

chilly basalt
#

So R = -2

#

here we got the remainder

brave tusk
#

sure

chilly basalt
#

If we move -2 to the left, we get $2a^2-4a-6 = (a+1)$Q

boreal girderBOT
#

VerifiedCrank

chilly basalt
#

We know that Q must have the leading coefficient of 2, because the leader coefficient of $2a^2-4a-6$ is 2

brave tusk
#

alright

boreal girderBOT
#

VerifiedCrank

chilly basalt
#

So we have the equation
$a^2-2a-3 = (a+1)(\frac{Q}{2})$

boreal girderBOT
#

VerifiedCrank

chilly basalt
#

do you know how to factorize?

brave tusk
twilit schooner
#

do you know how to solve quadratic eqs?

chilly basalt
#

ah I see, then just take this approach as a show as it would take a lot of time to teach this

brave tusk
#

oh yes

#

i do

#

mb

#

i just study in arabic

#

so i dont no the english terms

#

know*

chilly basalt
#

Alright, can you factorize a^2-2a-3?

brave tusk
#

sure

#

yes

twilit schooner
#

i think 3, -1?

brave tusk
#

(x-3)(x+1)

twilit schooner
#

(a-3)(a+1)

#

because it's a not x

brave tusk
#

yes my bad

chilly basalt
#

Right, so you got
$(a-3)(a+1) = (a+1)(\frac{Q}{2})$

boreal girderBOT
#

VerifiedCrank

brave tusk
#

mhm

chilly basalt
#

So $\frac{Q}{2} = (a-3)$

boreal girderBOT
#

VerifiedCrank

chilly basalt
#

pretty sure you know what to do next catthumbsup

#

This approach is slightly more complicated but beneficial in the long run

brave tusk
#

times 2 on the both sides to remove the 2

chilly basalt
#

and I actually have the third approach

brave tusk
chilly basalt
brave tusk
chilly basalt
#

improve your pattern recognition skill

brave tusk
chilly basalt
# brave tusk how

Do lots of questions, find their mutual solutions, and accumulate experiences

brave tusk
#

i see

chilly basalt
#

Alright, anything else?

#

I gotta go studying if it's alright for now

brave tusk
brave tusk
chilly basalt
#

no worries, have a good one

brave tusk
#

u too

chilly basalt
#

.solved

compact pewterBOT
#
Channel closed

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#
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maiden geode
compact pewterBOT
maiden geode
#

I don’t how to find that sin 2theta is negative when I am finding it’s positive, in interval -pi to 0

#

I multiplied the interval by 2 to -pi/2 - theta- 0 and got -pi - 2theta. - 0

#

I drawed the graph and I see it’s positive

#

Am I doing something stupid

#

<@&286206848099549185>

noble sorrel
#

can u tell which question are u talking about?

maiden geode
#

Sry

#

Should have said before

rancid mason
#

For a you just need to proof that the radius r is negative

maiden geode
#

Yup

rancid mason
#

You can do that by arguing that sine is negativ

noble sorrel
#

ur correct because its supposed to pe positive

maiden geode
#

But should be negative

noble sorrel
#

read the question again

noble sorrel
#

and since ur sin2theta can only be posit

rancid mason
noble sorrel
#

so there is no part of C in those region

maiden geode
#

Close

#

.close

compact pewterBOT
#
Channel closed

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compact pewterBOT
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open lance
#

can someone help me with geometry

compact pewterBOT
open lance
#

circles

strange ermine
chilly basalt
open lance
#

The vertex of the angle is outside the circle, its sides represent the sides of the triangle, and the angle is equal to the measure (in degrees) of the smallest circle inscribed in its sides. Find this angle.

#

i have to draw it myself cuz its just the question in the book

#

ok well how about this one

#

find the angles of abc triangle, <ACM=50

#

<BCN=70

jade nymph
open lance
#

why

jade nymph
#

All the angles would be 60

jade nymph
open lance
#

in the answers it says 70 , 60 , 50

toxic cipher
jade nymph
open lance
#

so whats the formula

#

i cant just write the answer the teacher will ask me how i got it

jade nymph
#

And there is the application of exterior angle theorem as well

open lance
#

but what abt the other angles

jade nymph
open lance
#

o

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can u help me with some more stuff

jade nymph
open lance
#

From a given point on a circle, a diameter and a chord equal to the radius are drawn. Find the angle between them

open lance
#

ok

jade nymph
open lance
#

no

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i dont have the answers to this books stuff

jade nymph
#

It’s 60 in my opinion

#

For sure

#

I must say

open lance
#

how do u solve it

jade nymph
#

@open lance btw can i ask which standard or course u are taking ?

jade nymph
open lance
#

idk im being tutored in math and i use 2 books 1 geometry 1 algebra

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and theyre in my native language so u wouldnt understand

jade nymph
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Oh

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@open lance where u from ?

open lance
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georgia

jade nymph
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Nice

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Do u want the explanation

open lance
#

is there like a formula

jade nymph
#

No

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There are multiple properties

simple maple
open lance
#

cuz its even more difficult to try and understand when the words r in english

simple maple
#

you dont need to. But if someone DOES speak it, they will identify so when the original is posted

open lance
#

im trying to use chatgpt as well but its not good at explaining

jade nymph
open lance
#

idk what equilateral means

#

😭

jade nymph
#

I’m sorry I’m unable to help u

open lance
#

alr im gonna try smth

#

.close

compact pewterBOT
#
Channel closed

Closed by @open lance

Use .reopen if this was a mistake.

#
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sacred snow
#

Hello I need help

compact pewterBOT
#

Please don't occupy multiple help channels.

sacred snow
#

So solve this question

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6 b

brazen quiver
#

@sacred snow do you know the Pythagorean theorem?

sacred snow
#

Yes

brazen quiver
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Can you set up the equation in the pythagorean theorem to solve this right triangle?

sacred snow
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Um how do I do that

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Can you show me

brazen quiver
#

Well, what is the equation?

sacred snow
#

A squared plus b squared = c squared

brazen quiver
#

Ok, now in that equation, which letter represents the hypotenuse?

sacred snow
#

C

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Since it’s the biggest angle

brazen quiver
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Angle? You mean side length yes?

sacred snow
#

Yes

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Sorry

brazen quiver
#

Ok, now assume you have a^2 + b^2 = c^2

We know that c is the largest side, which side in the 6b) triangle is the largest?

sacred snow
#

9 root 3

brazen quiver
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So we have a^2 + b^2 = (9√3)^2

#

We know another side length, let's call it b. Can you replace b into this equation?

sacred snow
#

Yes

brazen quiver
#

Go ahead and do that if you would

sacred snow
#

With 4root6

brazen quiver
#

So what is your equation now?

sacred snow
#

A squared plus 4 root 6 =9root3 squared

brazen quiver
#

Not quite! You forgot one detail

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b = 4√6, so b^2 = what?

sacred snow
#

Four root 6 squared

brazen quiver
#

Ok. So now we can simplify and solve for a.

sacred snow
#

Yes

brazen quiver
#

Both (4√6)^2 and (9√3)^2 are integers, what are their values?

sacred snow
#

Not sure

brazen quiver
#

Well, I'll do an example: (5√7)^2 = 5^2 * (√7)^2 = 25 * 7 = 175

#

Can you simplify yours?

sacred snow
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Sure

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A squared plus 576 =729

brazen quiver
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Show your work please

sacred snow
#

Um 😶

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16 x 36

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And then

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81x9

brazen quiver
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4^2 * (√6)^2 = 16 * 6

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Not 16 * 36

sacred snow
#

Oh

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Lemme change that

brazen quiver
#

Similar problem with 81 x 9

sacred snow
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A squared plus 96 = 243

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243-96

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147

brazen quiver
#

Ok

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a^2 = 147

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Now what?

sacred snow
#

Um

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Square root that

brazen quiver
#

a = √147

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Now can this be simplified?

sacred snow
#

Prime factorize

brazen quiver
#

Nice!

#

What do you get?

sacred snow
#

Equals 7 root 3

brazen quiver
#

You did it!

sacred snow
#

Yay

#

Can you accept my friend request

#

Ur a great teacher

brazen quiver
#

I can, but I cannot promise I'll be available.

sacred snow
#

And I really hope I can come to you for help in future

#

No problem at all

#

.close

compact pewterBOT
#
Channel closed

Closed by @sacred snow

Use .reopen if this was a mistake.

compact pewterBOT
#
Available help channel!

Send your question here to claim the channel.

Remember:
Ask your math question in a clear, concise manner.
Show your work, and if possible, explain where you are stuck.
Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!

Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.

drifting drum
compact pewterBOT
drifting drum
#

why is it important that a and b have no common factors?

daring axle
#

you didn't use the fact that gcd(a,b) = 1 in the proof

fathom crest
#

Say we have a common term 2, for the equation $$(5^b)^2=(10^a)^2$$ we could have positive and negative "solutions". Say a arbitrary number x, we can solve b for $$5^b=x \implies b=\log_5x$$ with the same logic, then we will get $$-5^b=x \implies b\log(-5)=\log_5x$$ which is not doable.

boreal girderBOT
fathom crest
#

I think I've seen something similar before, but I'm not sure if this was the explanation that "works".

daring axle
#

5^b = -10^a

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the proof they posted doesn't use gcd(a,b) = 1 even if it was (2a)/(2b) like you wrote out

their argument of comparing the parity between the left and right side is structurally the same

#

also don't we usually consider the simplest form so that we don't have to spend more time on an infinite descent argument

fathom crest
compact pewterBOT
#

@drifting drum Has your question been resolved?

drifting drum
#

yeah i was confused about that, good to know

daring axle
#

like some proofs of sqrt(2) being irrational

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use the fact that a/b is in simplified form

#

but you can do it without the gcd(a,b) = 1 requirement

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and even if you use the proof that rests on the gcd(a,b) = 1

#

u just have to use infinite descent on that to make it workable without gcd(a,b) = 1

drifting drum
fathom crest
#

Yes, since logarithms can't be negative.

drifting drum
#

i just don't see how if we have a common term 2, this means that we could also have negative solutions like -5^b = x

fathom crest
#

I didn't know what I though there, but you can do $$5^{2b}=2b=\log_5x$$

boreal girderBOT
daring axle
#

what i was getting at was

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if a/b = sqrt(2) where a and b are even

#

then you can imagine continuously dividing both the numerator and denominator repeatedly by 2

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and then you have a cycle of "infinite divisions"

drifting drum
#

you can do this with any numbers?

daring axle
#

eventually you may reach an odd number and then that makes no sense cuz we supposed that a/b was even

drifting drum
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and what if one was odd and the other even