#help-0

1 messages · Page 469 of 1

hollow bear
#

I don't think it won't be 6 or 10

lone heartBOT
#

@ripe berry Has your question been resolved?

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summer arch
#

am i on the right track?

lone heartBOT
verbal blaze
#

$$f'(x) = \frac{d}{dx} f(x) = \frac{d}{dx} x^{\frac{2}{3}} = \mbox{???}$$

ocean sealBOT
summer arch
#

quite honestly i was just plugging that stuff in to the equation that my notes have

fresh field
#

There exist standard formulas. Results that hold true throughout domain

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So, are you required to do it be definition?

summer arch
#

uhhh i dont think so

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we literally just started derivatives so im a little lost

fresh field
summer arch
#

this is the notes i was basing my work off

fresh field
#

Hold up

fresh field
summer arch
#

-4 right

fresh field
#

Can you show that

summer arch
fresh field
scenic eagle
#

Some 1 help me o

summer arch
#

i might have forgot that

fresh field
#

Anyways

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Now rewrite it correctly

summer arch
fresh field
#

Some a³+ b³ somewhere?

summer arch
#

in the numerator

fresh field
summer arch
#

uhhhh idk if this is right or not

glacial gyro
#

not quite

summer arch
#

the -2 would become positive from it right

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in the numerator atleast

glacial gyro
#

do you know the difference of squares identity

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and difference of cubes

summer arch
#

yeah i think so

glacial gyro
summer arch
#

ohhh i see

glacial gyro
#

you cant put the cube on the square and cube on the outside

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and from here you can use your identities and try and cancel something

summer arch
#

would the x^1/3 cancel out on top

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yeah idk where to go from here

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i kinda just want to solve the problem and get past it

glacial gyro
#

you would do difference of squares on the top

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which would get you (x^1/3 + 2) as a term

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and on the bottom do difference of cubes which also gets you (x^1/3 + 2)

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and you can cancel them

lone heartBOT
#

@summer arch Has your question been resolved?

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alpine sable
#

need help with this

lone heartBOT
#

@alpine sable Has your question been resolved?

tacit arch
alpine sable
#

i got stuck with 3+ 5cos^4x - 6cos^2x = 6/5 after it

livid sage
alpine sable
alpine sable
#

option a
cos^2x is 3/5

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thank youu

#

.close

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livid sage
#

but ur welcome

alpine sable
spark shard
#

oh u alr got it nvm

livid sage
alpine sable
alpine sable
livid sage
#

can u show?

alpine sable
livid sage
#

hm u wrote ((sinx)^2)^3 instead of ((sinx)^2)^4 for example

alpine sable
livid sage
#

yee fair enough

alpine sable
spark shard
#

ywyw

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neat folio
lone heartBOT
neat folio
#

I'm a bit confused bout part 2B here

#

I thought that given the cumulative distribution function F(x), the area between 1<=x<2 would be (x^4+5)/20

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instead of (x^4+4)/20

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given that the total cumulative probability will be 1/4 from 0 to 1

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I'm just wondering what I am misunderstanding or whether the answer is wrong

hushed locust
#

if you plug in x = 1 to the given function you should get 1/4

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so (1+4)/20 = 5/20 = 1/4 as expected

neat folio
#

but the answers use 4/20 instead

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are the answers wrong in that case.

hushed locust
neat folio
#

ah yep

#

I see

#

.close

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lone heartBOT
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@weary abyss Has your question been resolved?

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viral loom
lone heartBOT
alpine sable
#

do you want the solution?

viral loom
#

yeah

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i just want to check

void nymph
#

send it

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because !nosols

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lmao

viral loom
#

what?

void nymph
#

if you want your solution checked

#

you show the solution

void nymph
lone heartBOT
# void nymph because !nosols

As a helper, please do not give out answers that could be copied as a homework solution. Have the student work through the problem themselves and guide them along the way.

void nymph
#

!status

lone heartBOT
#
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6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
void nymph
#

you're 4 right

#

so show your work

viral loom
#

Oo

#

so 0<=i<=4, plug all of it into the prod:
prod(0j) + prod(1j) + prod(2j) + prod(3j) + prod(4j) = 0+120+120+60+20=320

void nymph
#

you're doing it manually hm

viral loom
#

whats the fast way

lone heartBOT
#

@viral loom Has your question been resolved?

void nymph
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broken falcon
#

guys, am i wrong for the yellow highlited part?

broken falcon
#

my friend said the standard deviation is supposed to be 1.46

lone heartBOT
#

@broken falcon Has your question been resolved?

pseudo ice
pseudo ice
lone heartBOT
#

@broken falcon Has your question been resolved?

lone heartBOT
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delicate cape
#

What is the value of x if sin x=12/13 and cos x=5/13 when x is between 0 and pi/2 ?

subtle birch
#

arcsin(12/13)

delicate cape
#

And how do I get to that answer?

mystic swallow
#

it's not really something you can generally calculate...

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it's not a very neat number

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arcsin(12/13) just means the value of theta b/w 0 and 0.5pi for which sin theta = 12/13

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i.e. sin(arcsin x) = x

void nymph
#

yep

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well

#

more like $\arcsin(12/13) + 2n \pi, n \in \mathbb{Z}$ but yes

ocean sealBOT
delicate cape
#

I was thinking x has a specific value

mystic swallow
#

it does have a specific value

void nymph
#

it was an infinite amount of values

mystic swallow
#

it just can't really be calculated

#

,w arcsin (12/13)

void nymph
#

all are specific though

mystic swallow
#

1.176 radians

delicate cape
#

Thank you

mystic swallow
#

np

void nymph
#

lmaoo

mystic swallow
#

!done

lone heartBOT
#

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void nymph
calm reef
#

are photos not allowed here

#

my photo got token down immediately

mystic swallow
#

no they are

void nymph
#

yeah they are

calm reef
#

any chance you guys can help me out with this

void nymph
lone heartBOT
#
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calm reef
#

whoops

#

i thought 0 was the main thing to ask my bad

lone heartBOT
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void nymph
#

now you can use it ig

lone heartBOT
void nymph
#

oh no.

#

!close

#

@calm reef

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.close

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calm reef
#

here right

void nymph
calm reef
#

oh okay

mystic swallow
#

@calm reef here

#

use that one

void nymph
#

or do that

#

lmao

lone heartBOT
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floral ocean
#

can someone help me with this please

lone heartBOT
mystic swallow
#

,rccw

ocean sealBOT
mystic swallow
#

jesus chr7st uh

#

hang on one sec

void nymph
#

not a fan

ocean sealBOT
mystic swallow
#

use this

floral ocean
mystic swallow
#

can't really see what you've done there

floral ocean
mystic swallow
floral ocean
lone heartBOT
#

@floral ocean Has your question been resolved?

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limber depot
#

how do i get the third equation... I know its 3 simultaneous

The 2 ones that are circled are the other 2 equations.

I know i have to do the dy/dx of ax^3 + bx^2 + cx -5 = (12)
when i do that i get 3ax^2 + bx + c = 12
but i have to get rid of the x for it to be a simultaneous? help ty

limber depot
#

or am i somehow supposed to deduce c

#

from the equation given?

#

like first point in ms is this buttt how do i get it

#

.close

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viral falcon
#

Here is the translation to English:

  1. Let ( A ) be the ( 3 \times 4 ) matrix

[
\left[\begin{array}{cccc}
1 & 2 & 3 & 4 \
5 & 6 & 7 & 8 \
9 & 10 & 11 & 12
\end{array}\right]
]

a) Solve the equation ( A x = 0 ). \
b) Express the solution set as a linear span of vectors in ( \mathbb{R}^4 ), and determine whether the vectors

[
\boldsymbol{y} = \left[\begin{array}{r}
1 \
-3 \
-3 \
1
\end{array}\right]
\quad \text{and/or} \quad
\boldsymbol{z} = \left[\begin{array}{r}
6 \
-9 \
2 \
2
\end{array}\right]
]

lie in the span. \
c) What is the general solution to ( A \boldsymbol{x} = \boldsymbol{b} ) for a given vector ( \boldsymbol{b} \neq \boldsymbol{0} ), if you are given that

[
\boldsymbol{x} = \left[\begin{array}{r}
1 \
2 \
-3 \
0
\end{array}\right]
]

is one solution?
d) Find what ( \boldsymbol{b} ) in the previous part must be, and express ( b ) as a linear combination of the columns of ( A ).

ocean sealBOT
#

Michael

viral falcon
#

What am I even supposed to show in c? And how do I do it?

#

Musn't $\vec{x}$ be expressed with $\vec{b}$?

ocean sealBOT
#

Michael

viral falcon
#

Oops, forgot to remove "Here is the translation to English" lol (I only translated it from my language with ChatGPT)

lone heartBOT
#

@viral falcon Has your question been resolved?

lone heartBOT
#

@viral falcon Has your question been resolved?

lone heartBOT
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warm osprey
#

Hi

lone heartBOT
gritty bramble
#

e?

warm osprey
#

I need help on this math question

#

My wifi is laggy so bear with me

#

Im sending a photo

#

I need help question 1 A)

alpine sable
#

!da2a

lone heartBOT
#

No need to ask “Can I ask…?” or “Does anyone know about…?”—it’s faster for everyone if you just ask your question! See https://dontasktoask.com/

warm osprey
dull lintel
#

,rotate

ocean sealBOT
warm osprey
#

I already solved and found out the Ts by substituting it in for all 3 times

#

But idk how to get m

#

I can do question 1 b and c cause they are easy, but idk how to do average velocity with 3 different times

#

Is there a specific formula?

gritty bramble
#

find how much it falls in that time

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and then divide by that time to get velocity

#

for example it falls 5m in the first second, so its average velocity is 5/1 = 5m/s

alpine sable
#

i mean

gritty bramble
#

oh wait

#

for the third second

warm osprey
#

Hnmm

#

Hmmm

gritty bramble
#

its average velocity would be (s(3)-s(2))/time

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similarly for eighth second it would be (s(9)-s(7))/t

alpine sable
#

s_n = u + a/2(2n-1) ((displacement in the eight second

warm osprey
#

Hmmmm

#

So for second 1, after subbing it in the equation i get like 315

gritty bramble
warm osprey
#

What do i use

#

The 315 for

alpine sable
warm osprey
#

Do i subtract it by smth /1- smth

gritty bramble
#

well

#

for the third it was s(3)-s(2)

#

what will it be for first?

#

s(1) -s(?)

warm osprey
#

0?

gritty bramble
#

yes

warm osprey
#

Tysm

gritty bramble
lone heartBOT
#

@warm osprey Has your question been resolved?

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round forge
#

Question: In how many ways can 4 novels, 2 mathematics books, and 1 chemistry books be arranged on a bookshelf if the novels must be together, but the other books can be arranged in any order?

round forge
#

My work thus far

#

Somehow by my logic I am doubling the correct answer but I don’t know why

twin nimbus
#

I am assuming all of the books may be distinguished from each other. So really we have two types of books: novels and other. Novels must be together, so we have 4 "items" (set of novels + 3 other books) we can arrange in total. And the novels themselves have 4 total orderings, so that is 4!(4!)

#

@round forge ^

#

Essentially, the your answer double counts the arrangements of the math books

lone heartBOT
#

@round forge Has your question been resolved?

round forge
#

Thanks! Mathematically I get it, I still can’t quite come up with my own quantitative justification but I get how you got that answer. Thank you!

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wraith valve
#

what i did may be completely pointless

lone heartBOT
wraith valve
#

!status

lone heartBOT
#
What step are you on?
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7. None of the above
#
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
twin nimbus
#

@wraith valve if you have |f(x) - f(y)| ≤ |x-y| what does this imply about the derivative?

wraith valve
#

it implies the that the f'(y) <= 1

#

wait

#

no

twin nimbus
#

Well |f'(y)| ≤ 1

wraith valve
#

yeah that

twin nimbus
#

In other words it is Lipschitz continuous

wraith valve
#

ight thank you

#

.close

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mellow cape
#

Hi can someone explain to me how to represent a linear inequality as a graph because I'm having trouble understanding it.

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quiet delta
#

Am I thinking correctly,$f_X(x)$ is the probability density function. $\int_{y}^{\infty}{f_X(x) dx} = \int_{0}^{\infty}{f_X(x) dx} - \int_{0}^{y}{f_X(x) dx} = 1 - F_X(x)$ ?

ocean sealBOT
#

Delusional J

tiny sky
#

i think you mean $F_X(y)$ at the end

ocean sealBOT
tiny sky
#

but yeah

#

(also here i think ur intending for X to be a non-negative r.v.)

quiet delta
#

I'm trying to use this in an attempt to prove $E(X) = \int_{0}^{\infty}{(1-F_X(x))dx}$ using the classical definition of $E(X) = \int_{-\infty}^{\infty}{xf_X(x)}$for a positive continous random variabel X

ocean sealBOT
#

Delusional J

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#

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wise jackal
#

why is a * b + a * b = a(b+b)

lone heartBOT
gray isle
#

distributive property

wise jackal
#

thanks

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sinful vortex
#

How did he get the length as 1.0785

lone heartBOT
sinful vortex
#

I have calculated it and got 1.1985

#

And it’s wrong

#

The problem is if you could not find the right length (dimensions) all the solution would be wrong

tacit arch
#

,calc 107 * 85

ocean sealBOT
#

Result:

9095
tacit arch
#

,calc (25 - 2 * 3/2 + 35 - 2 * 3/2) * 2 - 0.15

ocean sealBOT
#

Result:

107.85
tacit arch
#

oh that's a decimal

tacit arch
lone heartBOT
#

@sinful vortex Has your question been resolved?

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sage rose
#

hloo

lone heartBOT
sage rose
alpine sable
#

Yeah

sage rose
#

solve this?

alpine sable
#

solve

small lance
#

What’s the question?

alpine sable
#

for what

#

x and y?

sage rose
#

yep

#

i'm done with everthing but i'm stuck here

azure needle
#

Or whatever it's called

azure needle
sage rose
#

ouh thxs but wouldn't it be x instead of y?

azure needle
wooden bolt
sage rose
#

ouhhhh thanksss

#

mb i'm weak in maths bleakkekw

lone heartBOT
#

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twilit nebula
#

can somone help with this please i got the right answer and i didnt guess but it jsut made the most sense btu i cant find a way to work it out to the same answer

ocean sealBOT
tacit arch
#

power of power

twilit nebula
#

yea

#

but when i do that

#

as in ((7/3)^1/2)^2

#

i dont get 7/3

modern kernel
#

What is 1/2 × 2?

twilit nebula
#

is it somthn do with my calcualtor

modern kernel
twilit nebula
#

2 ways

#

ive tried doing it one by one

twilit nebula
modern kernel
#

Try doing it

(7/3)^(1/2×2)

twilit nebula
#

oh

#

wait why do i have to do it like that?

modern kernel
#

I'm not actually certain

twilit nebula
#

yea that works

#

what?

#

why doe sit only work some ways?

modern kernel
#

Because you're squaring 1/2

#

That becomes 1²/2²

#

I believe

#

Wait maybe not

modern kernel
twilit nebula
#

so its not just my calculator?

modern kernel
#

Yeah

twilit nebula
#

thx

#

ill have to note that down somwhere

#

do u know any websites with a lsit of all these weird input ways?

modern kernel
#

1/2 will have additional brackets

#

It solves the issue

twilit nebula
#

yea

#

but is there any ways to find these other than trial and error?

modern kernel
#

I guess

#

I understand

#

Why it happened

#

The operation you put

#

It actually looks something like this

#

Wait

#

As

#

By not giving the brackets at 1/2

#

The calculator does

(7/3)^1 and divides the whole by 2

twilit nebula
#

what

modern kernel
#

If you give this input : ((7/3)^1/2)^2

#

The computer won't understand that it's 1/2 if you don't specify it by giving brackets

#

You only want the 2 to divide the 1 so you gotta specify it

#

If you don't, the computer will think we will divide the whole with 2

twilit nebula
#

ooooh

#

so its reading it as

#

(7/3)^1 divided by 2

modern kernel
#

Precisely

twilit nebula
#

also im not allwoed to post mutiple questions in the same help channel right?

modern kernel
#

Absolutely

twilit nebula
#

kk

#

.close

lone heartBOT
#
Channel closed

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twilit nebula
modern kernel
#

You're absolutely allowed

#

My bad

vague agate
modern kernel
#

I read it wrong

twilit nebula
lone heartBOT
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storm marten
#

yeah seems right

alpine sable
#

yeah

#

z = y+z
180 = 2z
z = 90

#

similarly if z>y+z
z>90
and if z<y+z
z<90

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#
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alpine sable
#

welocme

#

,iamstudying

ocean sealBOT
#

Gave you the studying! selfrole.

burnt canopy
mystic swallow
lone heartBOT
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real pier
lone heartBOT
real pier
#

how can i find the 6

mystic swallow
#

6 is not equal to either 0 or 7

#

therefore x is not equal to either 0 or 7

#

therefore, the third expression

real pier
#

what does the third one thing mean, the = with /

alpine sable
#

not equal

real pier
#

oh okay

alpine sable
#

that x can't take that expression for x = 0 , 7

real pier
#

alr thanks guess i understand now

#

.close

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#
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dense lagoon
#

ans and question,
for part C whys the theta value for max 2pi and not 0?

gray isle
#

they specified positive values in the question

dense lagoon
#

ohh

#

yea mb

#

thx

#

.close

lone heartBOT
#
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fluid iris
lone heartBOT
fluid iris
#

i need helping understanding to solve for the slope. i under stand that it is asking for the rise which is x

gray isle
#

slope isn't just rise
and rise isn't x

#

did you watch the video guide?

fluid iris
gray isle
#

try to follow along with what they're doing

#

starting with picking two points
(ideally lattice points with easy to read coordinates)

fluid iris
#

right so i did (10,1) and then i did (-10,-3) and for that solution i got -2

#

here is another q relating to the Q

gray isle
#

how are you getting -2

fluid iris
#

but all was wrong. i am not fully following it seems

#

oh, should it be -1?

gray isle
#

how are you getting -1

fluid iris
#

i did -3 -(1) =

gray isle
#

whats that equal to?

fluid iris
gray isle
#

yes, -3-1 is -4

#

and what else are you doing for slope?

fluid iris
#

determine the vertical intercept?

fluid iris
gray isle
#

no

#

look at the slope formula

fluid iris
#

oh

gray isle
#

they did NOT say that slope is
one y coord minus the other

fluid iris
gray isle
#

-10-10 isn't 0

fluid iris
#

^^ this was b4

#

it was meant to be positive

gray isle
#

can you reattempt your calculations

fluid iris
#

sure 1 moment

gray isle
#

why are you doing
-10+10

#

and why are you now putting 4 for
-3-1

#

the way you set it up before was fine
you just made basic arithmetic errors

fluid iris
#

right

#

but isnt this the idea thats why -10+10

gray isle
#

no

fluid iris
#

they end up canceling out, no~

gray isle
#

they way you chose your first and second point, no

fluid iris
#

would it better to choose a diff point to make it easier?

gray isle
#

doesn't make a big difference

fluid iris
#

i spot a -5,-2

gray isle
#

yiu issue isn't with the choice of points

#

but rather with the arithmetic and plugging in your values

#

in your setup, your
x_2 = -10
x_1 = 10
x_2 - x_1 would be -10 - 10

#

what you had at the start
(-3-1)/(-10-10)
was completely fine
it's just that
-3-1 isn't -1,-2 or now 4,
-10-10 isn't 0

#

try not to overthink this subtraction

fluid iris
#

edit its -4

#

*-20

gray isle
#

yes, but thats equivalent to 4/20
so it's technically fine

fluid iris
#

yes. noted

gray isle
#

don't forget the fraction line
4/20 can be simplified further

fluid iris
#

0.2

gray isle
#

yes

#

for the following question you mixed up your intercepts

#

you gave the horizontal/x intercept

fluid iris
#

5▶️ and 0 ⬆️

#

the vertical

#

meaning the highest point

#

?

gray isle
#

no

fluid iris
#

oh my its -1

#

hmm if m = -4/20 then would those be the nums to plug in?

gray isle
#

why are you now saying that m is -4/20

fluid iris
#

4/20

#

error

#

my b

gray isle
#

and you simplified that earlier

fluid iris
#

correct.

gray isle
#

those would be the values you'd use

fluid iris
#

i have not sent the answer yet

#

gonna give it another shot

#

first pick any points '

gray isle
#

why does it look like you're multiplying your coordinates

cosmic mural
# fluid iris

average rate of change is (y2-y1)/(x2-x1) so the top would be only y coordinates and the bottom would be their corresponding x coordinates

cosmic mural
#

yes and remember you need to subtract them not multiply

fluid iris
#

so it would be -4/1? which is -4

#

i am need of help 🙏

#

so much help 😭

fluid iris
#

i might need to come back to this prob.

#

cause -5+9

#

or it would be -5-9

#

oh

#

-5-+9

#

plus 4

#

and bottom +9

#

4/9

cosmic mural
fluid iris
#

@gray isle should i open another ticket for the other qs?

#

for me this has been more exhausting that i thought

lone heartBOT
#

@fluid iris Has your question been resolved?

#
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shadow frost
#

I'm more focused on the bottom portion.

I have issues communicating with my calc 1 prof.

I just want to know how I know if the bottom goes to negative 0 or positive 0.

shadow frost
#

I know that I can input something like 05 becuase -5<x

That will give me -1/0(positive)

#

but we were using direct substitution.

dull lintel
#

what do you get when you put -4

shadow frost
#

for the bottom I'd get

16-4-12=0

dull lintel
#

what about for the upper one?

shadow frost
#

the upper one would give me a negative (-7)

dull lintel
#

so you get -7/0, you know the answer will be positive or negative infinity right?

shadow frost
#

Yeah, but I've also seen him put a negative in the 0 portion also.

#

like he did something like

dull lintel
#

okay now put a value less than -4 (this is what it wants) such as -5 and see the sign of the bottom part

shadow frost
#

bottom would be 8

dull lintel
#

so it is positive right (bottom is)

shadow frost
#

yeah postive 8 on the bottom and a negative on the top

#

so that would be negative infinity.

dull lintel
#

yes

shadow frost
#

So within a problem like peicewise when am I able to substitute out?

#

like

dull lintel
#

not sure what you mean by substitute out

shadow frost
#

factor

#

because if I can factor or when I get to a step I can factor I could just make it

#

1/|(x+4)|

dull lintel
#

I don't see any reason why can't you do that, not sure tho

shadow frost
#

I got points taken off for doing that.

#

He said review algebra on that one

wet linden
#

Are you allowed to graph it

#

Because that would be the easiest way

shadow frost
#

yeah we can do that, but we need to show the process we used to get to the point.

wet linden
#

You just draw the graph of 1/x+4

#

The asymptote is gonna be at x=-5

dull lintel
#

,w plot 1/(x+4)

wet linden
#

-4*

wet linden
#

Ye that’s how I would go about it

shadow frost
#

because

x>0 is positive x.
x<0 is -x within an absolute value expression

wet linden
#

What

shadow frost
#

yeah let me get it that's what's confusing me.

wet linden
#

Wait why do you have

#

An absolute value sign

shadow frost
wet linden
#

Here now

#

I’m confused

wet linden
shadow frost
#

Second let me get the full thing he posted on it

#

okay pause I might have just found out why I'm beyond confused.

#

In absolute value, if I have something like |x-5| and my x is -6

wet linden
#

Then you select the negative sign

#

like you + or - (x-5)

#

Then you would circle the negative sign

shadow frost
#

so on the outside of the absolute value there is a negative?

#

-|x-5|

wet linden
#

absolute value = + or - negative of a number

wet linden
#

Or positive

#

Depending on x value

shadow frost
#

okay so since I'm choosing in my problem above a value less than x, which is anything less than -4

#

I basically do

wet linden
#

Why do you still have an absolute value on the denom

#

I don’t quite understand

shadow frost
#

becuase I don't know how to get rid of it

wet linden
#

Oh is it in the problem

#

I didn’t see it

shadow frost
#

yeah so that's where I'm having the most issue. so in abs value

#

If my value is less than 0, I'm going to make the absolute value on the outside negative like the above, right

wet linden
#

No

#

It matters where the center is

#

You know how the absolute value graph is like a v

#

And there is a point where it meets

#

It matters where the x value is at that point

#

Like for lim as x approaches -2 |x+1|

shadow frost
#

If I chose something like -3

#

that would be -1

wet linden
#

Uh highkey bad example

#

Because it’s still 2

#

Because -(-3+1)

#

-(-2)

#

=2

shadow frost
#

Ohh I thought you were doing it for

#

Like for lim as x approaches -2 |x+1|

#

-2+1=1

wet linden
#

He

#

Ye

shadow frost
#

So if I factored

#

my orignal problem into |(x+4)(x-3)|

#

I would put a negative outside as it's less than by limit value (aka -4 and I'm going to the left) so -4.1

#

well no, it wouldn't be able to be that

#

!solved

#

.close

lone heartBOT
#
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lone heartBOT
#
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fossil pumice
#

I need help for this question

lone heartBOT
fossil pumice
#

not even sure where to begin

#

and it has to be an exact value

tacit arch
fossil pumice
#

I've read through that but it still doesnt really help, since this question is different thand normal halflife questions

#

I've checked a few halflife questions but for this one I don't know the initial value

#

but even if I find it

#

when I plug it into the formula the application still marks it as wrong

tacit arch
#

this example is extremely close to your problem

fossil pumice
#

hey thanks alot!

#

got the right answer thanks to that

#

I was messing up the k

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#

@fossil pumice Has your question been resolved?

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heady charm
lone heartBOT
heady charm
#

<@&286206848099549185>

#

<@&286206848099549185>

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#

@heady charm Has your question been resolved?

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grand trout
#

<@&286206848099549185>

lone heartBOT
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# grand trout <@&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.

verbal blaze
#

!da2a

lone heartBOT
#

No need to ask “Can I ask…?” or “Does anyone know about…?”—it’s faster for everyone if you just ask your question! See https://dontasktoask.com/

grand trout
#

Pls help me correct my proof in set theory anyone?

serene junco
#

Is it exactly that? Prove $A \subseteq A \cup B$?

ocean sealBOT
#

tatpoj

grand trout
#

<@&286206848099549185>

serene junco
#

to prove A is a subset of AUB?

#

If so, we shouldn't assume anything extra, like A being a subset of B

grand trout
#

Yes sir

grand trout
serene junco
#

No, let's actually start over

#

A lot of what you wrote here isn't quite right

#

To prove that $A \subseteq A \cup B$, you want to let $x \in A$, and then show $x \in A \cup B$.

ocean sealBOT
#

tatpoj

serene junco
#

Just from $x \in A$, how could we get to $x \in A \cup B$?

ocean sealBOT
#

tatpoj

lone heartBOT
#

@grand trout Has your question been resolved?

grand trout
#

Sir I have renew my proof

lone heartBOT
#

@grand trout Has your question been resolved?

lone heartBOT
#
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quiet pasture
#

dd

lone heartBOT
buoyant saddle
#

dd

#

just chilling hbu?

exotic sun
buoyant saddle
lone heartBOT
#

@quiet pasture Has your question been resolved?

naive valley
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pliant estuary
lone heartBOT
pliant estuary
#

,rotate 270

ocean sealBOT
pliant estuary
#

hi, can somebody please help me with solving this equation? i have never solved PDE's before, so i tried Fourier transform but that doesnt assume initial conditions, so i think thats an dead end

#

also this problem comes from plasma physics (electrostatics), so i think that at r=0 the initial condition should be something like 1/4piepsilon_0 but i am not able to find anything online

#

like a point charge

lone heartBOT
#

@pliant estuary Has your question been resolved?

pliant estuary
#

<@&286206848099549185>

lone heartBOT
#

@pliant estuary Has your question been resolved?

lone heartBOT
#

@pliant estuary Has your question been resolved?

radiant scarab
#

I need help with algebra
P1/(V1+V2)=P3/V3
i need to find V3

lone heartBOT
#
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sick lion
#

Point O is the centre of the circumscribed circle of the acute triangle ABC, in which AB > AC. Let X base the perpendicular lowered from B to AO, M be the middle of the BC, AA1 is the height of the ABC triangle. Prove that XM = MA1.

lone heartBOT
#

@sick lion Has your question been resolved?

sick lion
#

<@&286206848099549185>

silent oar
#

ill try it

#

gimem a bit

sick lion
silent oar
#

okee

sick lion
#

I know A1X || DC

#

I think we need to prove that BD || AC

silent oar
#

whats D

sick lion
silent oar
#

yea but what is it bnuuy

sick lion
sick lion
silent oar
#

im not sure how thats enough

#

unless you proved A1 X C D are on a circle

silent oar
#

ok i solved it

#

@sick lion do you want the solution or a hint

#

(i didnt use D)

sick lion
sick lion
silent oar
silent oar
#

anyways

#

let B1 on AC such that BB1 is perpandicular to AC

#

A B A1 X B1 are all on the same circle

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so angle BB1X=BAX=90-C

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also BB1M = MBB1=90-C

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so BB1X=BB1M so M X B1 are on one line

#

power of point from M with respect to (AB1XA1B) gives you MXMB1=MA1MB

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and since MX=MB

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then MA1=MX

sick lion
#

Thanks

#

.close

lone heartBOT
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silent oar
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void nymph
#

okay so what's this

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dusk tendon
#

I understand that this is the correct answer according to the SFTC but I don't understand why, how does taking the derivative of a definite integral to x change the variable in the derivative?

mystic swallow
#

it doesnt?

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you integrate, evaluate, and differentiate

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the actual variable is always x

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t is just a dummy variable for integration

glacial gyro
#

when you integrate it

dusk tendon
#

but the original integral was wrt t

glacial gyro
#

you plug in the x

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so for example

#

it will be (4/3)x^3+2x+c

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technically it will be t not x

mortal trellis
#

no +c

glacial gyro
#

definite

#

i mean the +cs just cancel with a definite

dusk tendon
#

+c still there but will cancel out, im following klint

glacial gyro
#

but yeah no +c

dusk tendon
#

klunt*

glacial gyro
#

it will have the t

#

and then you plug in the x for the bounds of integration

#

and then when you derive it will end up with the x

dusk tendon
#

can you do the same with a lower bound but in reverse? like for instance if the 0 was on top and x was on bottom?

glacial gyro
#

wym in reverse

dusk tendon
#

instead of 4x^2+2 it'd be -4x^2+2?

glacial gyro
#

-2

#

but yes

#

you could also just flip the bounds and make it negative

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one of the principles

dusk tendon
#

why does this work even if the constant bound isn't 0?

glacial gyro
#

yes because when you plug in a different constant

#

it will give you a number

#

and then when you derive it will just be 0

dusk tendon
#

oooooooh

#

so in a way, this works because the x is unresolved or w.e, im unsure the term

mortal trellis
#

imagine you have an antiderivative of the integrand. lets call it F(x). then you know that F'(x)=4x^2+2 because thats just what antiderivative means.

dusk tendon
#

and we still have to express the integral in terms of x

mortal trellis
#

and you know that the integral is equal to F(x)-F(0). or if the bounds were reversed then it would be F(0)-F(x)

#

now what happens if you differentiate that

dusk tendon
#

yea that makes sense, you're have to express it in terms of x cause you don't know what x is so in the end you'll have the (4/3)x^3+2x+c and that's what you're differentiating

#

ok i appreciate it, thank you that makes sense

#

♥️

#

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elfin bison
#

First one is the association law but if u make it that the sign in middle is not same as sign in bracket then it's distributive law right?

lone heartBOT
#

@elfin bison Has your question been resolved?

elfin bison
#

No

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@elfin bison Has your question been resolved?

elfin bison
#

Close

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Close

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Can I use distribution law

#

To get this

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@elfin bison Has your question been resolved?

obsidian night
#

!occupied

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spiral pumice
#

HELP! i dont understand how inputting a dependent vector into a linear transformation maintains its linear dependence! ):

spiral pumice
#

same thing with independent vectors

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in my mind the linear transformation is acting like a scalar?

#

just a really complicated one

#

i dont know if that holds up

hard oasis
#

Lets say dim(V) = n. If its dependent then we can deconstruct it into a linear combination of < n unit vectors, we can then map those unit vectors using the transformation and add them together in the image and get what we would have gotten if we has just mapped the original vector

spiral pumice
#

woah man ive been to 3 lin alg classes slow down 💀

#

what is dim(V) ?

hard oasis
#

The dimension of the vector space

spiral pumice
#

and you are saying there are n dimensions

hard oasis
#

What does it mean for a vector to be linearly independent vs dependent

spiral pumice
#

yeah honestly that explanation confused me more haha

#

okay so

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if its dependent

hard oasis
#

I can simplify sorry

spiral pumice
#

you can make one of the rows up from the other rows

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each column has a pivot

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doesnt*

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have a pivot

#

NOT EVERY COLUMN HAS A PIVOT

#

sorry

hard oasis
#

I think there's a slight misunderstanding here

spiral pumice
#

in my mind you are missing a vector that SHOULD be giving you a little more information about the matrix, so that you could map to every point in the vector space. this is because that last vector you needed to complete your collection gives you no new information

#

totally man ive been paying a tutor cause my professor is shit

#

i dont understand ANY of this 😭

hard oasis
#

Alright I'll give you a more concrete example

spiral pumice
#

THANK YOU

#

i like the concrete ones

hard oasis
#

Lets take the matrix $$\begin{pmatrix} 1 & 2 \ 2 & 4 \end{pmatrix}$$

ocean sealBOT
#

Bean Man

spiral pumice
#

yes

#

thats dependent

#

because the first row * 2 is the second row

hard oasis
#

Alright so the idea behind a linear transformation T is that if you input a vector, it has these properties alright

T(ax) = aT(x)
T(x + y) = T(x) + T(y)

spiral pumice
#

the vector has those properties?

#

or the transofrmation

hard oasis
#

the transformation

spiral pumice
#

uhhh

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could you show me a transformation?

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like an actual one

#

arent they kind alike functiuons?

hard oasis
#

Linear transformations can be represented as matrices

spiral pumice
#

okay

hard oasis
#

Yea lets just consider a transformation from $\mathbb{R}^2 \rightarrow \mathbb{R}^2$

$$
\begin{pmatrix}
1 & 0 \
0 & 2
\end{pmatrix}
$$

ocean sealBOT
#

Bean Man

spiral pumice
#

syes

#

that is the initial matrix?

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or the transformation

hard oasis
#

that is the transformation

#

For all vectors $x \in \mathbb{R}^2$

It is the case that $T(ax) = aT(x)$ for all scalars $a$ , and $T(x + y) = T(x) + T(y)$ for all vectors $y$

ocean sealBOT
#

Bean Man

spiral pumice
#

could you give me an actual example? i dont do well with the proof language

#

like if you had a vector
3
5

hard oasis
#

Gotcha

spiral pumice
#

the transformation of
3
5

would be the same as the two times the transformation of

1/2
5/2

#

right?

hard oasis
spiral pumice
#

what would it do to the vector

4
5

#

make it
4
10

?

hard oasis
#

We can check this easily by making
$$ x = \begin{pmatrix}

3 \ 5

\end{pmatrix}

Then we have that $$

\begin{pmatrix}
1 & 0 \ 0 & 2
\end{pmatrix} \cdot \begin{pmatrix}
a3 \ a5
\end{pmatrix} = \begin{pmatrix}
a3 \ a10
\end{pmatrix}
$$

Which is what we would get if we multiplied by $a$ after we did the transformation.

#

Oops

spiral pumice
#

whoops

#

haha

hard oasis
#

Thats better

spiral pumice
#

should the 2nd component in the vector say 2a5

#

or no

#

wait

hard oasis
#

it can be 2(a * 5) yea

#

wait

#

I'm slow

ocean sealBOT
#

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

hard oasis
#

There we go

spiral pumice
#

i think that makes more sense

hard oasis
#

Can you see that T(ax) = aT(x) or no?

spiral pumice
#

so what was the purpose of having the a's there

#

why not just have 3 and 5

#

yeah i can see it i think

hard oasis
#

T(x) = (3, 10)
T(ax) = (a3, a10)
aT(x) = a(3, 10) = (a3, a10)

#

a is just a random scalar that we're multiplying x by

spiral pumice
#

yeah okay

#

makes sense

#

that was very well put that last message

#

okay so how does this show that dependence is maintained through linear transformation

hard oasis
#

Alright, we can also show that T(x + y) = T(x) + T(y), and you need both of these properties to see why it maintains dependence/independence

#

Do you need me to show that as well?

spiral pumice
#

yes please

#

i appreciate it man

#

that one isnt as intuitive for me

#

i think we covered that in calc tho

#

like deriving 2x + y is the same as deriving 2x then adding it to the derivative of y

hard oasis
#

Alright, we'll work with the same matrix for a concrete example.

let $x = (x_1, x_2)$
and let $y = (y_1, y_2)$
$T(x) = (x_1, 2x_2)$

$T(y) = (y_1, 2y_2)$

Then $T(x + y) = T(x_1 + y_1, x_2 + y_2) = (x_1 + y_1, 2(x_2 + y_2))$

$T(x) + T(y) = (x_1 + y_1, 2x_2 + 2y_2) = (x_1 + y_1, 2(x_2 + y_2))$

ocean sealBOT
#

Bean Man

hard oasis
#

Does that make sense or do you need concrete numbers for x_1, x_2, y_1, y_2?

spiral pumice
#

can we do concrete numbers?

#

thanks man, its just a little abstract for me

hard oasis
#

Do you want to choose x and y

#

I'll just do $x = (1, 2), y = (3, 4)$

ocean sealBOT
#

Bean Man

spiral pumice
#

that works for me

#

that linear transformation matrix looked like the one you used before, yes?

#

the
1 0
0 2

hard oasis
#

?

spiral pumice
#

where it doubles the second component

hard oasis
spiral pumice
hard oasis
#

Yea I'm using the same transformation

spiral pumice
#

yes okay just making sure

#

bet thanks

hard oasis
#

Then $T(x) = (1, 4)$

$T(y) = (3, 8)$

$T(x) + T(y) = (4, 12)$

$T(x + y) = T(1 + 3, 4 + 8) = T(4, 6) = (4, 12)$

So we can see that they are equal

ocean sealBOT
#

Bean Man

spiral pumice
#

ohhh i think i can see it

#

you are adding up the components then transforming it?

hard oasis
#

yes

spiral pumice
#

and its the same as if you transformed the components then added it

hard oasis
#

exactly

spiral pumice
#

okay very well explained

#

sweet now onto the actual problem haha

hard oasis
#

Alright now we can show transformations maintain (in)dependence

#

It will have to get a bit abstract from here for you to fully understand the idea

spiral pumice
#

shit

#

okay

#

im ready! D:

hard oasis
#

We say that a set of vectors is linearly dependent if we can write one vector in the set as a linear combination of the others.

In our first example, we had the matrix $$ \begin{pmatrix} 1 & 2 \ 2 & 4 \end{pmatrix}$$

Which is the set of vectors (1, 2) and (2, 4). lets call the first one $x$ and the second $y$, then we can see that $2x -y = 0$ or $2x = y$

spiral pumice
#

yes

ocean sealBOT
#

Bean Man

spiral pumice
#

understood

hard oasis
#

Alright do you have an idea of a basis or no?

spiral pumice
#

basis?

#

no

#

unfortunately

#

wiat

#

wait

#

arent basic vectors like

#

1 0 0
0 1 0
0 0 1

hard oasis
#

Yea

spiral pumice
#

just one unit in each direction, visually

#

im pretty sure

#

3 blue 1 brown!

hard oasis
#

Yea, although not all basis vectors are like that but yea thats the canonical basis for $\mathbb{R}^3$

ocean sealBOT
#

Bean Man

hard oasis
#

So the basis tells us that we can represent all vectors in the vector space as a linear combination of the basis vectors

#

So in our case $x = \begin{pmatrix} 1 \ 0 $ \end{pmatrix} + 2\begin{pmatrix} 0 \ 1 \end{pmatrix}$ right

ocean sealBOT
#

Bean Man

spiral pumice
#

yes yes that makes sense

#

like getting it into reduced row echelon form

#

then using scalars

hard oasis
#

Alright, now you should be able to see that via our previous properties of linear transformations, instead of transforming x, we can transform its decomposition into unit vectors and get the same thing right

#

and likewise for y

spiral pumice
#

wait wait

#

how would you represent the vector
2
1
or something like that with the basic vectors

hard oasis