#help-13

1 messages · Page 155 of 1

elfin otter
#

Aight

#

Thanks pals :)

ancient valley
#

no prob :)

elfin otter
#

||I'll be back soon||

#

.close

cedar kilnBOT
#
Channel closed

Closed by @elfin otter

Use .reopen if this was a mistake.

#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

obsidian umbra
cedar kilnBOT
obsidian umbra
#

how do I come up with this polynomial?

#

i know one of the zeros is (x+4)

#

but the 1+2i is tripping me up

#

isn't there like a conjugate your supposed to do for that?

tropic oxide
tropic oxide
#

since you know 1 + 2i is a root, you know that what other complex number is a root?

obsidian umbra
#

1-2i

#

so you do (x-(2+i))*(x+(2-i))

#

right?

tropic oxide
#

why 2+i and 2-i

obsidian umbra
#

oh

tropic oxide
#

those arent the same numbers that you want as roots

obsidian umbra
#

mt

#

god

#

thats the mistake i made

#

god i can't read

#

or replicate

#

lol

#

so it would be (x-(1+2i)*(x-(1-2i)

#

?

spice kraken
#

yes

#

multiply all the (x-root)

obsidian umbra
#

thanks

#

.close

cedar kilnBOT
#
Channel closed

Closed by @obsidian umbra

Use .reopen if this was a mistake.

cedar kilnBOT
#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

celest heath
#

Can someone check both of these?

cedar kilnBOT
dusk finch
#

,w 2^24

#

the second one is correct

celest heath
#

thank you but what about first

slate lintel
#

,calc 240+1080

wraith daggerBOT
#

Result:

1320
celest heath
#

oh

#

u have to add 1080?

slate lintel
#

well

celest heath
#

why

slate lintel
#

it's any multiple of 360

#

because 360° is a full circle

celest heath
#

oh

#

but why not 360 why 1080

slate lintel
#

,calc 240+360

wraith daggerBOT
#

Result:

600
slate lintel
#

,calc 600+360

wraith daggerBOT
#

Result:

960
slate lintel
#

,calc 960+360

wraith daggerBOT
#

Result:

1320
celest heath
#

only one that fits

slate lintel
#

yeah

celest heath
#

oh u have to check all of them

slate lintel
#

I just went right to 1080 because I know that number from skateboarding

celest heath
#

lmao

#

,w 2^24

celest heath
#

damn this cool

#

thank you

#

.close

cedar kilnBOT
#
Channel closed

Closed by @celest heath

Use .reopen if this was a mistake.

cedar kilnBOT
#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

covert island
cedar kilnBOT
covert island
#

can someone help me on part a please!

#

im not sure where to go with this

brave aspen
#

Lets start with T1

#

What does it mean to be in Kernel of T1

#

I.e. what is true about elements of the kernel

cedar kilnBOT
#

@covert island Has your question been resolved?

covert island
#

right

#

so

brave aspen
#

So then kernel elements are

Vectors from where

#

(For t1)

covert island
#

the kernel elements are 0 from r^n -> r^k

#

??

brave aspen
#

They start as elements of what space

#

Before being transformed

covert island
#

oh

#

null space

#

?

brave aspen
#

They are elements of Rn

#

The kernel is a set of vectors from the domain space

covert island
#

right

#

sorry

#

so before transformation they are all elements of Rn

brave aspen
#

So to define and describe them we start by saying that kernel elements are

v in Rn

#

But it's not just any v

#

It's only certain v that adhere to particular conditions

#

Now this is where you say

#

Well

They should be v so that

Tv = 0k

covert island
#

im sorry my brain is like stapled to kernel = null space = to 0 vector

#

cuz i think thats what the professor was getting at

brave aspen
#

Yes they are the same thing

#

Basically

#

To define the first

#

We'd say

{ v in Rn | T1v = 0k }

#

I.e.

Vectors from Rn such that when T1 is applied to them you get the Zero Vector in Rk

#

That would be the definiton of the kernel of T1

covert island
#

mhm

#

let me just process rq lol

#

so the general equation rn is T(v) = 0 vector

#

for k

#

correct?

brave aspen
#

If youre part of the kernel, then that should be true

covert island
#

right ok

brave aspen
#

So that goes on the right side of the set as the restriction

#

But first you have to identify what kind of objects are even entering T1

#

Thats the left side of the set

Its vectors v from Rn

#

Not just any old thing

covert island
#

mhm

brave aspen
#

{ Objects of this type | that follow these conditions }

#

Thats how you define sets with set notation

#

You can also sometimes describe it in sentences depending on your class/prof

covert island
#

i think he wants it as a sentence

#

so then the definition of the kernel of T1 would be T1 * V = 0vector?

brave aspen
#

The definition requires two things:

Mention where the v is coming from

Mention what should be true about the v

#

So first you must say that

#

v is a vector from Rn

covert island
#

ohhh i get it i think so then

brave aspen
#

The kernel is:

The set of all v in Rn such that T1v = 0k

covert island
#

can you explain the k please?

brave aspen
#

Thats the sentence version of the definition

#

Yes

#

When you transform

#

Sometimes you go to another space

#

In this case T1 is defined

#

Rn -> Rk

#

Members of the kernel start in Rn

covert island
#

right so

#

v belongs to N

#

going to k?

brave aspen
#

But they end up in Rk

#

Yea T1 is like a vehicle

covert island
#

mhm

brave aspen
#

That carries the Rn vector

#

To a different location in Rk

#

So when you say T1v = 0

#

That 0 is AFTER transformation

#

So the 0 vector is not the one from Rn

#

It's the one from Rk

#

Each space has its own 0 vector

#

So you specify which one you reach

covert island
#

ok cool

#

that makes sense

covert island
#

right?

brave aspen
#

The 0 vector from Rk

#

Which your prof provided a notation for

#

I actually always just wrote 0 for zero vector it was never required of me to differetiate which one

covert island
#

ah ok

#

so then i have ker(t1) is t1 * v = 0k where v is a vector from Rn going to rk

#

or

#

no going to rk

#

is it important that i include that part?

brave aspen
#

Ker t1 is a set of vectors

#

Its not the equation

#

Its the vectors that go into it

#

So ker t1 is

All v in Rn so that T1v = 0k

covert island
#

cool lemme just process

brave aspen
#

Follow that structure

  1. Define element

  2. Explain restriction

covert island
#

ok so the defining the element part is here

covert island
#

and the restriction part is the linear transformation from n -> k

#

sorry if im a little slow btw, this is really hard for me

#

;-;

brave aspen
#

Let me rephrase this slightly

There is a 3 tier approach

  1. Identify what you are trying to define. In this case I am trying to define Kernel

Kernel is, ultimately, a set of many vectors.

  1. Once you know you are defining a set, you follow this procedure:

a. Begin by identifying where elements from this set originate from.

Once you do this, begin by introducing elements of the set.

In your case, Kernel is a collection of vectors. I need to specify what kind of vectors if possible. Because I know kernel includes input vectors, I can start by giving a broad description of elements of Kernel.

  • The Kernel is the set of all vectors v in Rn.....
#

Thats the first half of defining the set

covert island
#

right so we defined kernel to be a set of many vectors within a domain that result in the codomain -> 0

#

the element of T1 originates in r^n

brave aspen
covert island
#

and we can say this

brave aspen
#

You glue the two halves together to define the set

covert island
#

ok so i actually have a question about that

#

for this to be true

#

doesnt t1 have to be a matrix

brave aspen
#

All linear transformations have a matrix representation

#

Basically no not exactly but technically theyre all matrices sort of

#

Linear transformation can be defined without a matrix in some vector spaces and then you can make a matrix that fits the same transformation

#

For any possible linear transformation

#

For that reason the topics of Linear Transformation and Range/Kernel of Transformations is very closely linked to Null Space and Column Space of a Matrix

covert island
#

ok cool that makes sense

#

lemme write this down really quick 🙂

brave aspen
#

The kernel any linear Transformation is linked to the null space of some equivalent matrix representation of that same Transformation

covert island
#

ok cool

#

so all of this makes sense now

#

but

#

what about the T1 by T2 part

#

because that would be the dot product of 2 matrixes right

#

or is it the funciton of t1 with aspects to t2

brave aspen
#

Its basically

#

Composition

#

Do T1 and then apply T2

#

So where do things start in this transformation

#

Well if T1 is first

#

Then they came from Rn

#

So T1v happens

v rides to a new destination in Rk

So now v has become u in Rk

#

At this point you apply T2

covert island
#

mhm

#

it t1 first right

#

or no

brave aspen
#

Yea

#

T1 first

covert island
#

ok cool so lemme apply it

brave aspen
#

You go from Rn -> Rk -> Rm

#

In that transformation composition

covert island
#

ok cool lemme try it

#

so im sorry

brave aspen
#

Its ok no worries

#

Ask away

covert island
#

wouldnt that just mean its 0vectorN -> 0vector K -> M

#

0 vector M

#

**

brave aspen
#

It follows the same structure

#

Where are the things starting

covert island
#

so we start in vector N

brave aspen
#

Yes

#

So its

#

Set of all.vectors in Rn

#

That follow what restriction?

covert island
#

is it Rn

#

is the restriction Rn

brave aspen
#

What should be true about things in the kernel

covert island
#

they all = 0

#

0 vector*

brave aspen
#

Sure they are vectors from Rn

covert island
#

mhm

brave aspen
#

But ones that are in the kernel.of a transformation

#

So you describe it in terms of the transformation

#

What should be true about

T2 ° T1(v)

covert island
#

uhhhh im a little mega lost rn

brave aspen
#

So

#

T2 ° T1

#

Means do 2 linear transformations back to back

#

But actuallu

#

That whole process is itself also a linear transformation

covert island
#

right

brave aspen
#

So if im in kernel of T2 ° T1

covert island
#

so the first transformation would be t1

#

but what would t1's transformation be

#

??

brave aspen
#

It means that

T2°T1(v) = 0

#

It doesnt matter what happens in between

#

T1 sends everybody to an intermediate vector from Rk

#

But the final destination is what matters for kernel

#

The final destination is Rm

#

So regardless of what T1 did, once I apply T2 you get Zero

#

So you answer like this

Ker(T2°T1) :=

Set of all v in Rn such that T2°T1(v) = 0m

#

For a composition youre describing where you start and where you end, just like a regular single transformation

#

All the in between does not matter for the definition i dont care what happened when T1 was applied

#

Only what happens after T2 finishes

covert island
#

so no matter what

#

t1(v) will take us to 0

brave aspen
#

Its T2°T1

#

Think of that thing as one piece

#

Another way of writing it ks

#

T2(T1(v))

covert island
#

right

brave aspen
#

T1(v) may be non zero

covert island
#

but

#

the 0 vector?

brave aspen
#

But then T2 of that is zero

covert island
#

huh

#

but we said the def of ker(t1) is t1*v = 0

#

t1 v = 0 is the transformation right

brave aspen
#

For T1 by itself

#

When you do T1 followed by T2

covert island
#

right

#

and its T2(T1(v))

brave aspen
#

This is actually like a completely different transformation

#

Imagine it's T3

#

T3 starts in Rn and ends in Rm

covert island
#

true

brave aspen
#

Yes theres stuff in between but i dont care about T1v = 0

covert island
#

wait

#

u mean t2 right

brave aspen
#

Only the final T3v =0

covert island
#

right

#

so what im geting is this

#

T2(T1(v)) = 0

#

because no matter what the in between steps are

#

the final step will always be 0m

#

?

brave aspen
#

Yesssss

#

It doesnt matter if we hit 0 on the way or at the end

#

As long as at the end the final answer in Rm is Zero

covert island
#

ok cool

#

i think i get that

#

so we have 3 subspaces

#

rn rk rm

brave aspen
#

Yes

covert island
#

so how do we tell which 2 subspaces belong with eachother

brave aspen
#

Although youd probably just call them vector spaces outright

covert island
#

hmmmmmm

brave aspen
#

Basically

covert island
#

ok cool

brave aspen
#

R1, R2,....

#

Rn

#

These are all different universes

#

They are the "parent" vector space usually

#

Subspaces would be things inside each of these universes

covert island
#

right

#

so rn rk and rm are all different universes

brave aspen
#

Yes

covert island
#

ill take that

brave aspen
#

They have different dimensions

covert island
#

true

brave aspen
#

You can create a mini R3 equivalent subspace in R4

#

But R3 vector has 3 components

#

And R4 vector has 4

#

They are not the same class of object

#

So things from R3 could never be part of R4

covert island
#

so r^n has n components

brave aspen
#

Yes exactly

covert island
#

and things from r4 could never be a part of r3

#

right

#

?

brave aspen
#

Yes

covert island
#

so we know that n k and m

#

could have any amount of components

brave aspen
#

Yes its irrelevant to the question

#

They could all be equal

#

We don't know which is greater or less than the others either

covert island
#

right

#

there is no order to any of them

brave aspen
#

The only order we get is from the way T1 and T2 are defined

#

You can do T2(T1(v))

#

But can you do T1(T2(v))?

covert island
#

uhmmmm

#

i mean

#

doesnt it matter

#

on the dimension of the matrix

#

?

#

wait

covert island
#

?

brave aspen
#

Where does T2 send you to

#

Which vector space

covert island
#

t2 sends us to r^m

brave aspen
#

Ok

#

So if i do T1(T2(v))

#

Im going to try plugging in an Rm vector into T1

#

Does T1 accept Rm vectors as inputs?

covert island
#

no

#

it accepts rn

brave aspen
#

So this is an undefined quantity

covert island
#

WAIT

#

its Rn and Rk

#

but t2 doesnt accept Rn

#

right

#

or rM

brave aspen
#

If we do the other way

#

T2 ( T1(v))

#

We get T1(v) is a vector in Rk

#

T2 DOES accept Rk vectors

#

So T2 [ T1(v) ] is defined

#

Thats why your problem asks you about that one and not T1°T2

#

I gotta run for a bit im sorry if I have created more questions than I have answered, but hopefully you did get some answers xD @covert island

covert island
#

lol its ok

#

so then to sum it up

#

oh i get it now

#

thanks so much!

#

.close

cedar kilnBOT
#
Channel closed

Closed by @covert island

Use .reopen if this was a mistake.

#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

wintry roost
cedar kilnBOT
wintry roost
#

Find the indefinite integral

#

idk how to do this one

surreal cave
wraith daggerBOT
#

XxMrFancyu2xX

wintry roost
#

okay ty ill give that a shot

#

i'm confused so 5/(sqrt(x) | dx but then converting it to x^ndx the 5/sqrtx is throwing me off how do i know what x and n are?

#

@surreal cave

surreal cave
#

so using the first property $\int cf(x)\dd x=c\int f(x)\dd x$ called ``linearity" let's us move the 5 outside the integral so we get $5\int\frac{1}{\sqrt{x}}\dd x$

wraith daggerBOT
#

XxMrFancyu2xX

wintry roost
#

ah

wintry roost
#

oh

#

5 | x^1.5 / 1.5 + C ?

#

nvm got it now

#

5 | x^(.5) / (1/2) + C

#

which is 5| 2x^(.5) + C

#

so 10x^.5

#

@surreal cave is that right

#

.close

cedar kilnBOT
#
Channel closed

Closed by @wintry roost

Use .reopen if this was a mistake.

#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

wraith warren
#

hii

cedar kilnBOT
wraith warren
#

i have been on this for 30 mins

#

half a page of scarrtch paper

#

i give up

#

if you can please show work

slate lintel
#

I would start by dividing everything by 2

cedar kilnBOT
#

@wraith warren Has your question been resolved?

tranquil plank
#

also there's always cramer's rule

slate lintel
#

there is no need to drag Cramer into this

#

substitution or elimination will both work fine

wraith warren
#

hm

crimson sedge
#

the step-by-step should be free as long as you keep pressing next step

cedar kilnBOT
#

@wraith warren Has your question been resolved?

cedar kilnBOT
#
Channel closed

Closed due to timeout

Use .reopen if this was a mistake.

cedar kilnBOT
#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

fervent pike
#

Im so stuck

cedar kilnBOT
fervent pike
#

my work:

#

bigger screenshots, I basically did the same analysis on f'(x) and f''(x)

#

please help me I'm getting no where 😦

cedar kilnBOT
#

@fervent pike Has your question been resolved?

cedar kilnBOT
#

@fervent pike Has your question been resolved?

#
Channel closed

Closed by @fervent pike

Use .reopen if this was a mistake.

cedar kilnBOT
#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

dim tiger
#

hello everyone

cedar kilnBOT
dim tiger
#

shouldnt it become $\sum_{n=0}^{\infty}{n+1}{c_(n+1)}{x^(n+1)}$

wraith daggerBOT
#

calculus is fun

crimson delta
#

it helps to write out the first ~5 terms of the series explicitly

dim tiger
crimson delta
#

$\sum_{n=0}^\infty (n+1)c_{n+1} x^{n+1}$

wraith daggerBOT
#

Denascite

dim tiger
#

tysm

dim tiger
crimson delta
#

no

dim tiger
#

why is that

dim tiger
#

i tried first 3 terms and they are all different

crimson delta
#

what are the first few terms

dim tiger
#

for the summation on the LHS the first few terms are $c_1,2c_2 x,3c_3 x^2$..., the first few terms of the summation on the RHS are $0,c_1 x^2,2c_2 x^3.$..

crimson delta
#

yes so right hand side is exactly x^2 * left hand side

wraith daggerBOT
#

calculus is fun

dim tiger
#

wait a sec i totally forgot the x^2 on the LHS

#

tysm i wasted your time by such a silly question

crimson delta
#

happens

#

dw

dim tiger
#

have nice day/night depending on your location

#

.close

cedar kilnBOT
#
Channel closed

Closed by @dim tiger

Use .reopen if this was a mistake.

#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

random kelp
cedar kilnBOT
random kelp
#

for ii, is it even possible to get 3 points that satisfy the conditions

#

because if you take the derivative of y, you get only 2 solutions, 1 of which is (2,3)

short blade
#

L1 is not normal to C

#

L2 and L3 are normal to C and parallel to L1

lunar lynx
random kelp
short blade
#

show your work

lunar lynx
#

yeah.

random kelp
lunar lynx
#

L2 and L3 are parallel to L1. Therefore slope of L2 and L3 will be same as ... ?

#

@random kelp

random kelp
lunar lynx
#

Good.

random kelp
#

thats what ive done though

lunar lynx
#

Now, Since L2 and L3 are perpendicular to C, why are you equating them to derivative at those points.

#

Derivatives give slope of tangents. Not of perpendiculars.

random kelp
#

because thats how you calculate the slope at a given point

short blade
#

you don’t want the slope at those points

#

you want the slope of the normal at those points

lunar lynx
random kelp
#

they are parallel to L1

#

so how can they be normals to C

junior dome
#

do you know m1m2 = -1?

random kelp
#

I do..

short blade
#

what you’ve done is set y’ = m

#

this says

#

let the tangent line to y have slope m

#

but that’s not what you want

lunar lynx
short blade
#

do you recognize that mcmeny?

random kelp
#

I understand

lunar lynx
#

,w graph |x|

wraith daggerBOT
lunar lynx
# wraith dagger

here tangent at x=1 is parallel to line y = x+1, which is normal to same curve at x=-0.5.

random kelp
#

i see

#

so I need to locate the points on the graph that are equivalent to the slope -1/3 cuz thats the perpendicular point

lunar lynx
#

Yes

lunar lynx
random kelp
#

so I gotta make 6x^2-12x+3=-1/3

lunar lynx
#

Yes

random kelp
#

why didnt i think of that

cedar kilnBOT
#

@random kelp Has your question been resolved?

#
Channel closed

Closed by @random kelp

Use .reopen if this was a mistake.

#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

fair mortar
#

$\int_0 ^{\frac{\pi}{2}} \frac{\sin 2x}{\cos^4 x + \sin^4 x} dx$

wraith daggerBOT
#

Bettim

fair mortar
#

I should get pi\4 but idk where I did my mistake

mighty shuttle
#

the answer is pi/2

fair mortar
#

,w integrate (sin2x)/(cos^4x + sin^4x) from 0 to pi/2

livid hound
#

missing /

wraith daggerBOT
fair mortar
#

Oh okay

#

It's my teachers mistake then

#

Thank youu

#

.close

cedar kilnBOT
#
Channel closed

Closed by @fair mortar

Use .reopen if this was a mistake.

#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

fair mortar
#

$\int_0 ^a \arcsin \sqrt{\frac{x}{a+x}} dx$

wraith daggerBOT
#

Bettim

fair mortar
mighty shuttle
fair mortar
mighty shuttle
#

let me check, just a moment

upbeat forge
# fair mortar

have you tried using polynomial substitution like t=tan => sin = 2t/1+t^2 cos = 1-t^2/1+t^2 ?

mighty shuttle
# fair mortar

seems about right, though you techically have to change the limits first

fair mortar
fair mortar
#

How to proceed

mighty shuttle
#

IBP

fair mortar
#

Ohhhh

#

Can I take the entire remaining trigs to be dv

#

U is thera

upbeat forge
fair mortar
#

Right

mighty shuttle
fair mortar
#

I have trouble finding limits

#

Can you help me

mighty shuttle
#

sure

fair mortar
mighty shuttle
#

upper limit:- $a=atan^2(\theta) $ so $\theta$ is $\frac{\pi}{4}$ unless I'm mistaken

wraith daggerBOT
#

physicsrocks

fair mortar
#

That's what I used

#

,w integrate arcsin(sqrt(x/(x+a))) from 0 to a

fair mortar
#

Lol where answer

mighty shuttle
#

,w integrate (xtan(x)sec^2(x)) from 0 to 1

wraith daggerBOT
fair mortar
#

,w integrate (xtan(x)sec^2(x))

fair mortar
#

Wtf

mighty shuttle
#

yeah, when you IBP that's what you get $x\int(tan(x)sec^2(x)dx)-\int \frac{tan^2(x)}{2}dx$

wraith daggerBOT
#

physicsrocks

fair mortar
#

Howw

mighty shuttle
#

wdym

fair mortar
#

I got xtan²x/2 - tanx+x

mighty shuttle
#

how

#

can you show your working?

#

you've sent two pages, send the one before that

fair mortar
#

There nothing before that

mighty shuttle
fair mortar
mighty shuttle
#

,rotate

wraith daggerBOT
mighty shuttle
#

seems right, but I'm still unable to see how you got the $-\theta$

wraith daggerBOT
#

physicsrocks

fair mortar
#

Tan²x is sec²x - 1 no,?

mighty shuttle
#

yeah, my bad. Let me try integrating this manually. I'll get back to you in a minute

fair mortar
#

Okayy

#

It's right i got it YAAAAY

#

Thanks 🙏

mighty shuttle
#

wdym, your original answer was right, how did you geta different answer?

fair mortar
#

My original answer wasn't right

#

I forgot the /2 for the second 2 terms inside the Paranthesis

mighty shuttle
#

nah, MSE says that your answer to ∫xtan(x)sec^2(x) is right

fair mortar
#

What is msw

#

Mse

mighty shuttle
#

Math satck exchnage

fair mortar
mighty shuttle
#

ah, got it.

fair mortar
#

Ye

#

Thanks anyway

#

.close

cedar kilnBOT
#
Channel closed

Closed by @fair mortar

Use .reopen if this was a mistake.

#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

tidal wasp
cedar kilnBOT
tidal wasp
#

.close

cedar kilnBOT
#
Channel closed

Closed by @tidal wasp

Use .reopen if this was a mistake.

crystal raptor
#

Maybe try it another time

dawn junco
#

stop ddosing the texit bot they'll find you

wanton sail
#

No spamming

#

Oh this isn't even your help channel

#

@tidal wasp Sorry about that.

steel seal
#

can you crash the bot doing that?

wanton sail
#

Feel free to post your question in a new help channel.

wanton sail
cedar kilnBOT
#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

sand cradle
#

Determine all $x \in \mathbb R$ s.t. $(x-3)(x+5)(x+9)(x+15) > 3$.

sand cradle
#

How would you approach this?

#

(By the way, there isn't really a pattern to the numbers here, I picked them randomly and would like to see how one would solve something like this generally)

tropic oxide
#

By the way, there isn't really a pattern to the numbers here,

#

there's your problem

#

there's very little hope that this quartic you've got factors nicely

crimson sedge
#

and I'd like to add to Ann and say that there's nothing that can be generalized here

tropic oxide
#

no, one can extract from this the general idea that kepe wants to learn how to solve polynomial inequalities.

sand cradle
#

To determine the set that x can be in

tropic oxide
#

not unless $(x-a_1) \dots (x-a_n) - k$ has a nice factorization you can't.

wraith daggerBOT
sand cradle
#

Alright, thanks

crimson sedge
sand cradle
tropic oxide
#

no, that interval will only be a subset of our solution set

sand cradle
#

x, infty, sry

tropic oxide
#

unless you can produce proof that (x+1)(x+3)(x+5) = 3 has only one root

#

which i am not sure it does

sand cradle
#

oh

#

Thanks

#

.close

cedar kilnBOT
#
Channel closed

Closed by @sand cradle

Use .reopen if this was a mistake.

#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

harsh sparrow
#

Hey guys I have a question relating to probability and static.
If I was to have a book with 500 pages, how would I count how many letter of "A" are inside the book?

harsh sparrow
#

I had a rough idea of how it would be such as dividing the pages from "a", doing 500 divide by 1/26, would this be correct?

livid hound
#

no

#

what's your reasoning for doing that

harsh sparrow
#

Cause there was 26 letters in the alphabet I thought it would be 1/26 or something

#

And use it to divide to 500

#

How would you approach this?

#

Or is it simple as just 500/26?

livid hound
#

no

#

firstly the letters aren't evenly distributed

#

some letters are more common than others

harsh sparrow
#

Oh okay

#

Gotcha

livid hound
#

as for

500/26
are you implying that on average a appears once every 26 pages?

harsh sparrow
#

Nope

livid hound
#

because that's essentially what that calculates

harsh sparrow
#

Hmmm

livid hound
#

a basic approach would be to count the number of a in one page

#

and multiply that by 500
and that'll give a decent estimate

harsh sparrow
#

Hmm okay

#

CAuse I don't want to use a sample

#

Since it was incorrect way of doing it according to my senior

livid hound
#

well then you'll need access to some external data

harsh sparrow
#

I was told to do what the question is requesting for

livid hound
#

about how often a is used compared to other letters

harsh sparrow
#

No clue

livid hound
#

size of the page / number of words that could fit would also be relevant

harsh sparrow
#

Would I be able to find that?

#

Or would it be unknown?

livid hound
#

depends on the exact wording of the question and what is expected

#

are you expected to reach a numerical amount or
just the approach to how to obtain a reasonable estimate

harsh sparrow
#

I think just the chances of it

#

So a reasonable estimate

livid hound
#

you'll still need a bit more info

harsh sparrow
#

Hmmm

#

OKay I see

livid hound
#

some sort of sampling would be required

harsh sparrow
#

Hmmm

#

Yeah it's tough

#

I am suppose to do it without sampling

livid hound
#

i have a cabinet with several draws filled with fruit

how would you expect to know how many oranges i have knowing nothing about the cabinet

harsh sparrow
#

HMmmm

#

Yeah that's good point

livid hound
#

like there's

harsh sparrow
#

But would it be accurate if I just whip out any book to do it

livid hound
harsh sparrow
#

?

livid hound
#

but that's based off another sample

harsh sparrow
#

Hmmm

#

This is rough

livid hound
harsh sparrow
#

and probably more letters etc?

livid hound
#

i suppose you could estimate the number of words on a page

#

by multiplying words/line by number of lines

harsh sparrow
#

Yeah that makes sense

#

And then divide it by 8% (a)

#

?

livid hound
#

multiply

harsh sparrow
#

You don't divide at all?

livid hound
#

~~8% of those words have a

#

of is multiply

harsh sparrow
#

OHHH

#

Right

#

So let's say in those 500 pages there is roughly idk 2500 letters in each page

#

So it would be like 500 x 2500 x 8%?

livid hound
#

you'd want words/page

#

the data is % of words the letter appears in

harsh sparrow
#

Oh okay

#

Would you please show me how you would do it?

#

Was I on the right track for it or?

livid hound
#

its pretty much all been outlined

#

you just need to put it together and not make typos

harsh sparrow
#

Ohhh okay

#

Understood

#

Thanks so much

#

I got the gist of it

harsh sparrow
livid hound
#

wdym by it

harsh sparrow
#

Oh

#

I think I am confusing myself now

livid hound
#

you'd want words/page
i suppose you could estimate the number of words on a page
by multiplying words/line by number of lines

#

500pages/book * number of words/page
will give
number of words/book

harsh sparrow
#

So it would be 500 * 2500?

livid hound
#

2500 is a bit high for number of words on a page

harsh sparrow
#

But just an example it would be something like that?

livid hound
#

if there happened to be a book that has 2500 words on a page, sure

#

but to my knowledge there aren't any that come close to that

harsh sparrow
#

Ohhh okay

#

I don't have to multiply by 8%?

livid hound
#

you will

harsh sparrow
#

Oh okay cool

#

I will be on the right track now right?

livid hound
#

but currently the focus is on having a more realistic number for words on a page

harsh sparrow
#

Oh okay

#

Gotcha

livid hound
#

i suppose you could estimate the number of words on a page
by multiplying words/line by number of lines

harsh sparrow
#

Thank you so much!

#

I know what I can do to get an rough answer for this

#

.close

cedar kilnBOT
#
Channel closed

Closed by @harsh sparrow

Use .reopen if this was a mistake.

#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

drowsy hare
#

does anyone know how this question would acutally work?

drowsy hare
#

I have gotten G(w) and I know b is pi

#

so i have subbed in G(w-b) but do i have to multiply it out after this?'

cedar kilnBOT
#

@drowsy hare Has your question been resolved?

cedar kilnBOT
#

@drowsy hare Has your question been resolved?

flint plinth
wraith daggerBOT
drowsy hare
flint plinth
#

(although i have to leave for an appointment in 7 minutes, so it might have to wait until I get back)

drowsy hare
#

yeah sure but its long hahaha

#

This is everything with all the things I have tried along the way

flint plinth
drowsy hare
cedar kilnBOT
#

@drowsy hare Has your question been resolved?

cedar kilnBOT
#

@drowsy hare Has your question been resolved?

cedar kilnBOT
#

@drowsy hare Has your question been resolved?

cedar kilnBOT
#

@drowsy hare Has your question been resolved?

drowsy hare
#

.close

cedar kilnBOT
#
Channel closed

Closed by @drowsy hare

Use .reopen if this was a mistake.

#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

subtle horizon
cedar kilnBOT
subtle horizon
#

To solve this

#

I first did trial and error

#

and tested values of n => 0 and <0

#

and got 0 1 -1 and -2

#

when i added them

#

i got -2

#

but the answer is 12

#

however

#

if we look at the absolute value part

#

you might think that you need to kind the modulus of each integer then add

#

but the last part of the questions says nothing about modulus

#

How should I apply the absolute value thing to solve the question?

spice kraken
#

just solve the inequality

south tundra
#

First pretend like you are solving for |N - 3| in the inequality rather than for N

#

Meaning you get it to the form a > |N - 3| > b for some numbers a and b

#

Then you simply consider the cases N >= 3 or N < 3

south tundra
#

thonk Well if you had an equation like e^(2x^2 + 8) - 1 = 0, you would start with isolating e^(x^2) because you then can use logarithms, similar thing here

south tundra
south tundra
#

15 > 30/|N - 3| > 6
So
1/15 < |N - 3|/30 < 1/6

#

Now you multiply each side by 30 and get 2 < |N - 3| < 5

#

Let us now consider the cases

#

The first case being N >= 3

#

What's |N - 3| equal to in that scenario?

subtle horizon
upper ruin
subtle horizon
#

x

upper ruin
#

|x| = x if x ≥ 0, it is - x if x < 0

subtle horizon
south tundra
#

The latter can be rewritten as N >= 3

#

That's why we are considering that case

subtle horizon
#

ok

subtle horizon
upper ruin
#

Consider the two cases, N > 3 and N < 3

topaz shore
#

Can someone help with this one

upper ruin
#

And solve the inequalities given

south tundra
upper ruin
topaz shore
#

sorry

upper ruin
#

Don't worry

south tundra
#

Same thing for the other case, try considering N < 3 on your own now

subtle horizon
south tundra
#
  1. |N - 3| >= 0 for all N anyway
  2. That's not an equation
upper ruin
south tundra
subtle horizon
upper ruin
south tundra
#

Why do you think it's 3?

subtle horizon
#

n-3=0

#

n=3

upper ruin
south tundra
#

I never said N - 3 = 0

subtle horizon
#

n-3 ≥ 0

#

n ≥ 3

upper ruin
subtle horizon
#

why is |n-3| =n-3

#

as n-3 >= 0

south tundra
#

The definition says that if x >= 0, then |x| = x, right?

subtle horizon
#

yes

south tundra
subtle horizon
#

why are we finding the modulus of n-3

south tundra
#

Because we have modulus of n - 3 in our problem and we need to get rid of it

subtle horizon
#

ok

#

So we need to change it to a variba

#

variable

south tundra
#

You can, but it is not really necessary

subtle horizon
#

|n-3 |= n-3

south tundra
south tundra
subtle horizon
#

Ok

#

Sor

upper ruin
subtle horizon
#

if N-3 >=0

#

S0

#

n must be more than n>=3

south tundra
south tundra
south tundra
#

Okay, so the solution in the first case is (5, 8)

south tundra
#

If N - 3 >= 0, then |N - 3| is the same as N - 3. Simiarly, the inequality 2 < |N - 3| < 5 is then the same as 2 < N - 3 < 5

subtle horizon
#

ok

#

so

#

5< n<8

south tundra
#

Yes, that's the solution to the first case. Now we need to move onto the second case. Namely, we need to consider N - 3 < 0

#

What's |N - 3| equal to if N - 3 < 0?

subtle horizon
#

that is -(n-3)

#

-n+3

south tundra
#

Correct

subtle horizon
#

1 < N <- 2

south tundra
#

Yes

#

Let's now look at the integer solutions

#

What integer solutions does 5 < N < 8 have?

subtle horizon
#

?

#

What

south tundra
#

Can you think of any integers that are placed between 5 and 8?

subtle horizon
#

6 7

south tundra
#

Right

#

And what are the integer solutions to 1 > N > -2 then?

subtle horizon
#

0 -1

south tundra
#

Yup

#

So, what do we get when we sum up 6, 7, 0 and -1?

subtle horizon
#

12

#

Wait

#

So first

#

Posting for reference

#

So we look at the inequality

#

And because we are looking for n-3 without the modulus sign

#

we need to apply the rules

#

that | n-3 | = n-3

#

When n-3 is more than zero

south tundra
#

Yes

subtle horizon
#

Then we imagine situation when

#

n-3 is positive

#

and remove modulus signs

#

then solve

#

we get the range

#

then we do that for when it is less than zero

#

then get range

#

We then get the integer values of n and sum them

south tundra
#

That is right

subtle horizon
#

But can you please expllain why they began the question like that

south tundra
#

Like what exactly?

subtle horizon
#

no worry

#

.close

cedar kilnBOT
#
Channel closed

Closed by @subtle horizon

Use .reopen if this was a mistake.

#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

late finch
cedar kilnBOT
late finch
#

Hello- I've been stuck on this for quite some time.

#

this is the full problem

#

possibly relevant defn

spice kraken
#

!status

cedar kilnBOT
#
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'm told it's wrong
4. I got an answer and would like my work checked
5. I have a question about someone else's worked solution
6. None of the above
late finch
#

1

#

I mean

#

I don't know where to begin

#

I was thinking of opening it up and doing any many integrals

#

but that sounds like a headache >_>

spice kraken
#

you finished part a right?

late finch
#

oh yeah yes

#

by counter example though

cedar kilnBOT
#

@late finch Has your question been resolved?

spice kraken
#

counter example?

#

the generalization should be true though

late finch
#

The generalization is an inequality

#

Direct equality is not possible

spice kraken
#

do you mind showing me your proof?

#

we use the equality in part a to show the inequality in part b

cedar kilnBOT
#

@late finch Has your question been resolved?

late finch
#

(X,Y)->(e^x cosy, e^x sin y)

#

Jacobian determinant is always non zero therefore it's invertible or kernel is just the zero vector

#

But the map is periodic

#

So LHS 0 RHS non zero

#

Possible

cedar kilnBOT
#
Channel closed

Closed due to timeout

Use .reopen if this was a mistake.

late finch
#

.reopen

cedar kilnBOT
#

late finch
#

There might not be a neat solution

cedar kilnBOT
#

@late finch Has your question been resolved?

cedar kilnBOT
#

@late finch Has your question been resolved?

dire geode
#

That's the first thing you should try

#

This problem is just an application of the definition of the norm

late finch
#

what do you mean?

snow lily
#

Question please

late finch
late finch
late finch
dire geode
late finch
#

I'm doing
|| f(x) - f(y) || = || integral ( Jacobian . (b-a)dt) t || being parameter for line

#

then moving the norm inside and taking inequalities

#

is that right 0-o?

late finch
#

.solved

#

.close

cedar kilnBOT
#
Channel closed

Closed by @late finch

Use .reopen if this was a mistake.

#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

round raven
#

hey there, i actually posted the question before but then i had to go so i couldnt get an answer. I am solving an old exam to prepare for my exam soon and there is a question for a multivariable function f(x,y) = (x^2)y + ((y+1)^2)(y+2). The sub-task I couldnt figure out is the part where it asks for me to find all singular points on the curve 0 = f(x,y) and classify them with the help of the hessian matrix as double point, cusp and hermit. I of course did some research on it but i couldnt find something and the script my prof provided doesnt explain it well. Thanks in advance.

snow lily
#

first singular point are defined with Df(x,y)=0 so df/dx=0 and df/y=0

round raven
#

oh i already know that but thanks, i probably should've been more clear. I am more confused about the classifying part

snow lily
#

for Hessian Matrix you calculate 3 terms d^2(f)/dx^2 (you already calculated df/dx), d^2(f)/dy^2 (you already calculated df/dy) and df/dxdy than you replace the 3 expressions with the coordinates of singular points and you write the matrix : 1st line (d^2(f)/dx^2 df/dxdy)

#

2nd line ( df/dxdy d^2(f)/dy^2 )

#

This is so helpful in optimization problems because you can use this matrix to find the convexity of f in this certain point

round raven
#

i see, after that how do i know if a singular point is one of the three categories?

snow lily
#

lets consider H=1stline(r s) 2nd line(s t)

#

you calculate the determinant D

#

if D<0 we can't conclude

#

if D>0 we test r

#

r>0 so f is convex

#

if r<0 f is concave

round raven
#

oh i thought this method was being used to find local min/max or saddle points

#

i mean of course you can also figure out if its convex or concave but i didnt think we'd use it for the classification of singular points

snow lily
#

if it is convex or concave in a point so it's a local min or max

round raven
#

my english is advanced but still not my first language and im not sure what hermit means in this context, I translated it from the file which is in german, which is my 2nd foreign language so could you shortly explain what that is exactly. Idk why doesnt any dictionary provide something for this context.

#

like is it an isolated-point or something idk

#

.close

cedar kilnBOT
#
Channel closed

Closed by @round raven

Use .reopen if this was a mistake.

cedar kilnBOT
#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

boreal trail
#

why is it 0.52 - 0.24

cedar kilnBOT
boreal trail
#

and not 5*10^8 - the other

#

.close

cedar kilnBOT
#
Channel closed

Closed by @boreal trail

Use .reopen if this was a mistake.

boreal trail
#

nvm

cedar kilnBOT
#
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.
After 15 minutes, feel free to ping <@&286206848099549185>.
• 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.

potent fiber
#

is the 1 cm a third of the whole length or not?

lunar lynx
potent fiber
leaden otter
#

Not really

lunar lynx
potent fiber
#

uhh

#

then where should i start?

leaden otter
#

Do you see the trapeziums

#

What are the lengths of it's parallel sides?

potent fiber
#

the smaller side is 1?

kindred storm
# potent fiber does octagon work like this?

You can slightly alter that. The middle part is fine if you want to say the sides of the octagon are length 1, but then you have, with the triangle in the upper left, a hypotenuse that's the same width as the top side of the octagon.

potent fiber
#

i think

leaden otter
kindred storm
#

Then the two legs of the upper left triangle are the same length because of symmetry.

kindred storm
#

Yes, do you see the upper left triangle?

potent fiber
#

these?

kindred storm
#

Well, that's the upper right, but yes.

#

Those are the same size because a regular octagon is symmetrical.

#

So, use a variable for the length of one of the legs.

#

Then write it next to both legs.

potent fiber
#

then it tells you its 1

kindred storm
#

Then write 1 next to the hypotenuse.

leaden otter
#

This might help, same colour lengths are equal

kindred storm
#

No, the legs aren't 1. The hypotenuse, one of the sides of the octagon, is 1.

slate lintel
#

what

#

the strip is 1cm wide

potent fiber
#

should it be like this?

kindred storm
#

Ahh, yes, that's right.

#

And then the other leg is 1.