#help-33

250800 messages · Page 255 of 251

still temple
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no problem

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when you done with a problem dont forget to .close

merry ivy
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is the formula used geometric?

still temple
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yeah the one were using is geometic, you may also hear it refured to as exponentinal

merry ivy
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the formula i wrote down is
A n = a1 (r^ni1)

still temple
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the alebraic forumla is

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$C_n = 1.1^n*9$

elfin berryBOT
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aspwil

still temple
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that looks fantasitc, one sec

merry ivy
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?

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should i close?

still temple
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no we dont do homework for people, we explain how to do homework. if you need help see #❓how-to-get-help

still temple
merry ivy
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im going to close so i can give this channel to you

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.close

marsh citrusBOT
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marsh citrusBOT
wind chasm
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looks good to me

crystal plover
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A bit complicated to me

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And what I got is just 9e^(3x)+14

wind chasm
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2nd derivative?

crystal plover
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Yup

wind chasm
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huh

tacit fjord
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yh it should not be a lot

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i dont know wth has happened there

tacit fjord
wind chasm
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wait where did ln come from

tacit fjord
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how the heck are there logs

wind chasm
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in the first step

wind chasm
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cramming for this test

crystal plover
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Well

wind chasm
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there shudn't b logs in this problem

tacit fjord
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no

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its just plain wrong

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$x^2$

elfin berryBOT
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Shuri2060

tacit fjord
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The derivative of this is 2x

wind chasm
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first derivative is 3e^(3x) + 14x

crystal plover
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$$\frac{d}{dx}(e^{3x}) = 3e^{3x}$$

tacit fjord
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how the hell do you get logs

elfin berryBOT
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skypirate

tacit fjord
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you're confusing things

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The derivative of 2^x is (ln 2)2^x

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just no.

wind chasm
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u don't use logs when dealing with e as the base

tacit fjord
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you're just mixing things up

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and as a result somehow confused on this problem

wind chasm
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I think he gets it

tacit fjord
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$$y' = (e^{3x}+7x^2)'$$
$$= (e^{3x})'+(7x^2)'$$
$$= (e^{3x})'+7(x^2)'$$

elfin berryBOT
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Shuri2060

wind chasm
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On a side note can any1 solve my question on related rates in help-10

tacit fjord
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?

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You realise this line is nonsense?

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How do you even get it

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y is certainly not equal to this

wind chasm
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ok

tacit fjord
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You just randomly decided to multiply the first thing by 3

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and the next thing by ln7x and 0

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yes?

wind chasm
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@last magnet derivative of e^3x is 3e^3x right?

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u agree?

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then u have 7x^2 afterwards

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just use power rule then

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it becomes 14x

tacit fjord
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It doesn't matter what method you use, as long as it's correct

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Right now you have something which is anything but

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Why did you randomly decide to differentiate

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you write y =

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Only on the next line you start writing y' =

wind chasm
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ok so now u have 3e^3x +7x

tacit fjord
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Do you see the inconsistency here to begin with?

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Alright, next, assuming the typo

wind chasm
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they're asking for 2nd derivative

tacit fjord
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That isn't how to differentiate 7x^2

wind chasm
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9e^3x +7

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think that's it

tacit fjord
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Look man

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there's no point giving the answer

wind chasm
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I'm not I'm tryna explain it :/

tacit fjord
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When they have a fundamental misunderstanding of how derivatives work

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$$(x^2)'$$

elfin berryBOT
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Shuri2060

tacit fjord
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First you need to recognise this MUST be differentiated using the power rule

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There is literally no other way

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What you are trying to propose is plain wrong.

tacit fjord
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Show how then

wind chasm
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no

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just take the derivative of y'

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that's all the 2nd derivative is

tacit fjord
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There is no regular way

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and non-regular way

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there is only one way

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$$x^2 = e^{\ln x^2} = e^{2\ln x}$$

elfin berryBOT
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Shuri2060

tacit fjord
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If you are proposing something like this

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It's just... totally unnecessary

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and you're doing it wrong even so

wind chasm
tacit fjord
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The answer is definitely not what you wrote.

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Or maybe, just recognise the power rule

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x^2 -> 2x

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$$y' = (e^{3x}+7x^2)'$$
$$= (e^{3x})'+(7x^2)'$$
$$= (e^{3x})'+7(x^2)'$$
$$= (3e^{3x})+7(2x)$$
$$= 3e^{3x}+14x$$

elfin berryBOT
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Shuri2060

tacit fjord
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So this is what you should have written down for the 1st derivative

wind chasm
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. . .

tacit fjord
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wrong and wrong

marsh citrusBOT
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@last magnet Has your question been resolved?

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sonic roost
marsh citrusBOT
hexed solar
elfin berryBOT
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BrownMunde

sonic roost
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Thanks

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.close

marsh citrusBOT
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marsh citrusBOT
whole sleet
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Is that (z1/z2)/z3 or z1/(z2/z3)?
Note they are different

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I'm guessing by your work, it should be (z1/z2)/z3

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Anyway, you can write the division in rectangular form. See this source:
https://www.cuemath.com/numbers/division-of-complex-numbers/

Dividing complex numbers is mathematically similar to the division of two real numbers. We need to find a term by which we can multiply the numerator and the denominator that will eliminate the imaginary part of the denominator so that we end up with a real number in the denominator.

marsh citrusBOT
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still temple
marsh citrusBOT
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@still temple Has your question been resolved?

civic moss
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Multiply both sides by 3

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@still temple

still temple
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or u multiply 2

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?

civic moss
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Look

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$$3 \cdot \frac{2x + 5}3 = 3 \cdot 7$$

elfin berryBOT
civic moss
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$$2x + 5 = 21$$

elfin berryBOT
still temple
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oh u mutplpy the 7?

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alr

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so when u mutply the 3 it canel itself right

civic moss
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Right

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Yeah 3 times something divided by 3 equals that thing

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Think about it

still temple
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ill try to do the problem now

civic moss
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Ok

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R u in algebra rn

still temple
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yes im in gr 10

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Is that correct

marsh citrusBOT
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still temple
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Can anyone help find the range pls

marsh citrusBOT
still temple
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I got -8<y<10

marsh citrusBOT
#

@still temple Has your question been resolved?

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marsh citrusBOT
humble mortar
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I’m in 10th grade and I finished a unit on that a while ago

marsh citrusBOT
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dreamy fulcrum
marsh citrusBOT
dreamy fulcrum
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what am i doing wrong?

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oops, wrong screenshot. Meant to attach this:

opaque wolf
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Might they possibly want f(x) in the limit box

dreamy fulcrum
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just tried it, I got an error saying that the only symbols allowed are numbers and x

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and-+ and whatever

opaque wolf
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by f(x) i mean each piecewise function

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So as the limit approaches 0 from the left, which function would be used to find the limit

dreamy fulcrum
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oh i see, instead of the derivative

opaque wolf
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then evalulate what it approaches

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Maybe

dreamy fulcrum
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let me see

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no, unfortunately

remote elbow
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Are you sure you didn't mix up the left and right hand side?

dreamy fulcrum
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I've tried both to make sure

opaque wolf
remote elbow
dreamy fulcrum
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i tried the one above, and this:

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along with:

opaque wolf
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this is weird it looks like you have the concept down but i have no clue what they want to input

remote elbow
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Again make sure you understand limits approaching from the left and right

dreamy fulcrum
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Regardless of which way the limit approaches from, the derivative should be the same, right?

remote elbow
noble nebula
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aren't you?

noble nebula
remote elbow
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You lucked into the correct derivative. The first step is understanding which function in the piecewise to use for the left hand and right hand limits

opaque wolf
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Remavas how did you speedrun active

noble nebula
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yes

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Honest answer: I don't know

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I spent a couple of days with these help channels

opaque wolf
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Both you and Gamer Dio got it out of nowhere

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I guess I have to get on the help channel grind for that ethos

noble nebula
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Probably 🤷

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I have about 3k messages

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maybe that's the threshold

opaque wolf
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@dreamy fulcrum ^

dreamy fulcrum
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oh

opaque wolf
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try putting in -5 into the 2nd box

dreamy fulcrum
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Oh. i see the problem then

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it doesn't like that either

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how

opaque wolf
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can you see the answer? I have no clue what's happening

dreamy fulcrum
noble nebula
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yes

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from 0-, use the 9x^2 + 2x part

dreamy fulcrum
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I've tried that as well. It doesn't accept it

dreamy fulcrum
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alright im giving up

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will ask prof tmrw

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thank you guys though! i appreciate it!!

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.close

marsh citrusBOT
#
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stray edge
marsh citrusBOT
stray edge
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im not suire hwo to use the cross product

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to find area

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ive found qp x qr

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to be [-7, 7, 3]

cunning citrus
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Norm of cross product gives area of the parallelogram spanned by those vectors

cunning citrus
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compare with the trig formula for area

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$A=\frac{1}{2}ab\sin(C)$

elfin berryBOT
cunning citrus
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$a=\norm{u} \
b=\norm{v} \
C=\theta \implies A=\frac{1}{2}\norm{u}\norm{v}\sin(\theta)=\frac{1}{2}\norm{u\cross v}$

elfin berryBOT
stray edge
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why does |u x v| = |u||v|sin(theta)

cunning citrus
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the norm of uxv is just that

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Google a proof/look for the proof in your text catshrug

marsh citrusBOT
#

@stray edge Has your question been resolved?

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lost stream
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I need help with this question

marsh citrusBOT
lost stream
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I don't understand what they are trying to ask me

warped goblet
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It's the gray region

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The intersection of A' and B'

still temple
lost stream
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IV

still temple
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Well I thought II is what he meant by grey

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The background is grey yea

warped goblet
lost stream
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so

still temple
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How is it the interestcion of a and b

warped goblet
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A prime

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And B prime

lost stream
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it's intersection of A' and B' because they dont want anything in a or b just outside of it

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and IV happens to be the universal set

lost stream
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Ok good

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what would the difference be if it was a union?

still temple
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He didn't ask to define that

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He wanted to answer of the question

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The IV part on the background

warped goblet
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Which is wrong

lost stream
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ya i'm asking what would be the difference

warped goblet
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Oh

lost stream
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if it was a union

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like how do u notice it is a intersection

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instead of a union

warped goblet
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Union of A' and B' includes the parts where A' doesn't intersect with B'

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Intersection is a region where both of them occur at the same time

still temple
warped goblet
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Basically A union B is a region where either A or B occurs, but A intersect B is a region where both A and B must occur

still temple
lost stream
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I get your first explainatioin

warped goblet
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Yea A intersect B is II

lost stream
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ur second one about intersection sounds similair to the first tho

still temple
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And then what is IV

lost stream
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sorry

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I don't get your second definition

warped goblet
still temple
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Ya

warped goblet
warped goblet
# lost stream

For example A union B is the area of both of these circles, but A intersect B is just the area of II

lost stream
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ohh

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so union would've been the whole thing

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nah I get it dw

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thank you

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!

warped goblet
lost stream
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If you don't mind I will post a problem question later on

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if you'd like to help

warped goblet
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Sure if I'm around

lost stream
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Ok so this question I got n(H')-n(F)

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would that just mean my answer would be -9

warped goblet
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Idk what's the full question but it's basically the number of elements which are not in the set of H minus the number of elements in the set of F

lost stream
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since it doesnt want whats in the H set

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should I get my intersected ones and -?

marsh citrusBOT
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@lost stream Has your question been resolved?

karmic jay
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@lost stream for nH' get values in F which doesnt have mutuality with H and for F take all values of F

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and yeah it makes the solution negstive

lost stream
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ok I got -9

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do u reckon that is right @karmic jay

karmic jay
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No

lost stream
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how come?

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You said get the values of F minus the ones that have a mutuality with H

karmic jay
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that doesnt have*

lost stream
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ya my fault that doesnt have a mutuality

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the only ones mutual are the J heart, Q heart and K heart

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and since they dont want nothing in H

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I got J spade, Q spade, K spade, J diamonds, Q diamond, K diamond, J clubs, Q clubs, K clubs

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which is 9

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@karmic jay

karmic jay
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And subsract it by nF

lost stream
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ya which is 0?

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wait what

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Nf is those that I mentioned

marsh citrusBOT
#

@lost stream Has your question been resolved?

marsh citrusBOT
#
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wooden schooner
marsh citrusBOT
wooden schooner
wooden schooner
#

<@&286206848099549185>

marsh citrusBOT
#

@wooden schooner Has your question been resolved?

marsh citrusBOT
#

@wooden schooner Has your question been resolved?

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sharp jay
#

If I've proved the first statement, how can I prove the second?

marsh citrusBOT
#

@sharp jay Has your question been resolved?

plush elk
#

You prove a general statement, that is P(D)((e^rx)u(x))=(e^rx) P(D+rI)(u(x)) where D(f(x))=f’(x) and I(f(x))=f(x) P is a polynomial

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This can be done by proving inductively that D^k((e^rx)u(x))=(e^rx)(D+rI)^k(u(x))

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Then P(D) is just a linear combination of D^k for some k, for the same reason , P(D+rI) is also a linear combination of (D+rI)^k for those k with the same coefficients. Add those equations for each k together you get this general result

sharp jay
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this is where im at

plush elk
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What?

sharp jay
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thats my proof for the first part

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and then i bs the second part bc idk how to prove it with the summation

plush elk
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For example,D(f(x))=f’(x),D^2(f(x))=f’’(x). Given a polynomial P(t)=2t^2+4t+5

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P(D)(f(x))=2f’’(x)+4f’(x)+5f(x)

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Got it now?

sharp jay
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oh ok

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are we talking about the second part or first part?

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like is my first part right?

plush elk
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P(t)=2t then P(D+rI)(f(x))=2(D+rI)(f(x))=2f’(x)+2rf(x)

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No

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I am talking about the statement I gave you

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And your problem is just a special case of that statement

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You see P(t)=Π(t-r_j) in this case

sharp jay
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ok

plush elk
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You are proving P(D)((e^rx)u(x))=(e^rx) P(D+rI)(u(x)) where P(t)=Π(t-r_j)

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But you can prove it for any polynomial P just as what I said

sharp jay
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t or d/dt?

plush elk
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No No, t is just a indeterminate, you can choose any symbol for example s, P(s)=3s^2+7s-6 if you like

sharp jay
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so in this case t=d/dt?

plush elk
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No

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You are not listening at all

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D=d/dx

sharp jay
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im listening i j dont understand im sorry

sharp jay
plush elk
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If P(s)=Σa_j s^j, and you have proven using induction that for any j, D^j((e^rx)u(x))=(e^rx)(D+rI)^j(u(x)), then multiply a_j on both sides, and add those equations together you have your result.

sharp jay
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i have no clue where all these letters are coming from

plush elk
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Then I am done, cause I gave every definition, I don’t know why you refuse to understand

sharp jay
#

youre trolling

plush elk
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I don’t know where I could possibly make it more clear

sharp jay
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then youre just a terrible teacher

plush elk
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Where exactly, what symbol you don’t understand?

sharp jay
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where the hell is a_j and s^j coming from

plush elk
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Polynomial my god

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You don’t know what polynomials are? Like p(s)=4s^3-7 is a polynomial

sharp jay
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yes i know what a polynomial is

plush elk
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a_3 =4, a_0=-7 this case

sharp jay
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i never knew this notation. i understand now.

plush elk
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Okay please continue, since your confusion is cleared

sharp jay
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s^j?

plush elk
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?

sharp jay
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i just would rather use the symbols from the problem bc idk how any of them relate

plush elk
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S is the indeterminate

sharp jay
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right but i still dont know what that means

plush elk
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You can use any letter you want as I said

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You had problem with t so I used s instead

sharp jay
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oh

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s is the variable of the polynomial

plush elk
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Yeah. Use whatever you want, G, p(G)=3G+17

sharp jay
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i prefer t

plush elk
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Okay

sharp jay
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ok so take me step by step

plush elk
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Replace every s with t

sharp jay
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lets start by are you proving statement 1 or 2 rn?

plush elk
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No your question one and two are both results of that statement I gave. I am telling you how to prove the statement

sharp jay
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oh so youre proving both simultaneously?

plush elk
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Your question 1 is the case where P(t)=t-r_j, your question 2 is the case where P(t)=Π(t-r_j)

sharp jay
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oh ok

plush elk
#

I am proving the statement, your questions are going to be solved instantly simultaneously

sharp jay
#

ok

#

so what is the statement again?

plush elk
sharp jay
#

so can you explain P(D)

sharp jay
#

and is e^rx e^{rx} or x e^r

plush elk
#

e^(rx)

sharp jay
#

D(P) then? why is it P(D)?

plush elk
#

No, no. I didn’t do anything to the polynomial, I didn’t take derivative of it, nothing

#

I use that example again:

#

P(t)=2t^2+4t+5 then

#

P(D)=2D^2+4D+5I

#

Just like D is a map from functions to functions , mapping f(x) to f’(x)

sharp jay
#

whats the i or l on the end

plush elk
#

P(D)=2D^2+4D+5I is also a map from functions to functions, mapping f(x) to 2f’’(x)+4f’(x)+5f(x)

plush elk
#

I is the identity map, mapping f(x) to itself

#

If(x)=f(x)

sharp jay
#

gotcha

#

may i ask what the point is of even including it then if it does nothing

plush elk
#

What do you mean nothing? It solved your questions as corollary

#

It’s actually useful sometimes in ODE

sharp jay
#

are you sure there isn't a simpler way to prove this? we didn't go over any of this stuff :/

plush elk
#

But I don’t study analysis, I just happen to see that formula of a MIT ODE lecture video when I was a high school student

#

Why are you reluctant? It didn’t generalize much, just replaced P(t)=Π(t-r_j) with any polynomial P

sharp jay
#

its just hard to read in this type of font

#

im not grasping much of it

plush elk
#

It didn’t bring up any new idea new result

#

Just rephrased your question in a more clear and general form

sharp jay
#

i dont understand how to prove your second line tho "by induction" or whatever

plush elk
#

If that’s true for k , you prove it’s true of k+1

sharp jay
#

and i have no idea how to do that

#

is D^k the kth derivative

plush elk
#

That is if D^k((e^rx)u(x))=(e^rx)(D+rI)^k(u(x)), you show that D^(k+1)((e^rx)u(x))=(e^rx)(D+rI)^(k+1)(u(x))

#

Yes

#

Just D^(k+1)=D(D^k)

#

Apply D on both sides of D^k((e^rx)u(x))=(e^rx)(D+rI)^k(u(x))

sharp jay
#

apply?

#

oh like take the derivative of both sides?

plush elk
#

D^k((e^rx)u(x))=(e^rx)(D+rI)^k(u(x)) therefore

#

D[D^k((e^rx)u(x))]=D[(e^rx)(D+rI)^k(u(x))]

#

Yes

sharp jay
#

like product rule?

plush elk
#

Yeah, product rule on right hand side

sharp jay
#

oh i was gona do that with e^rx u

plush elk
#

D((e^rx)v(x)) where v(x)=(D+rI)^k(u(x))

#

The left hand side is D^(k+1)((e^rx)u(x))

sharp jay
#

dont know how to take derivative of (D+rI)^k u

plush elk
#

You don’t need to

sharp jay
#

im lost then

plush elk
#

I feel like I am feeding you the answer. D[(e^rx)(D+rI)^k(u(x))]= [(e^rx)(D+rI)^k(u(x))]’=(e^rx) [(D+rI)^k(u(x))]’+(re^rx)[(D+rI)^k(u(x)]=(e^rx) D[(D+rI)^k(u(x))]+(e^rx) rI[(D+rI)^k(u(x))]=(e^rx)(D+rI)(D+rI)^k(u(x))=(e^rx)(D+rI)^(k+1)(u(x))

sharp jay
#

its ok im just trying to understand this. i wont even answer the question with what youre giving me bc i dont get it. i think i j give up.

plush elk
#

I feel so helpless, nothing I say can make you read it. No matter how detailed I explain, no matter how many extra explanations I want to add, there is nothing I can do to make you accept it.

sharp jay
#

im clearly not as advanced as you are

#

i dont want you to think im denying your explanation. i truly cannot comprehend. but its not your fault.

plush elk
#

Many people just hate to see anything they are not familiar with , unless it comes from their superior, if their school force them to learn

#

Otherwise there’s no reason for them to learn anything at all

sharp jay
#

i hate seeing it bc i dont understand it

#

i want to learn it but i cant learn what youre telling me in an hour

plush elk
#

I am willing to explain it in any way you like. Anything you still don’t understand, I am happy to add extra explanations, give examples. But I am not the one that’s reluctant

#

I am willing to go through it as many times as you need but you have quitted.

sharp jay
#

i j feel bad wasting your time

#

i cant learn through this

plush elk
#

Yeah many people just keep saying they can’t. Anyway, if you change your mind I am here available.

sharp jay
#

i appreciate it. if my prof gives a solution, maybe ill compare it with yours and see if it helps.

sharp jay
#

.close

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vagrant mural
marsh citrusBOT
vagrant mural
#

How do I integrate things with stuff underneath the fracture?

long arch
#

you have to spot a reverse chainrule i think its called

#

if you have the integral of f'(x)/f(x) then it evaluates to ln(f(x))

vagrant mural
#

Can u show me on the 1st question

long arch
#

and the first integral is (f'(x)/2)/f(x) so if you factor out that constant of 1/2 you get it in the right form

vagrant mural
#

And I'll do the 2nd

#

Cause I don't understand it with words. I tried to integrate the top and bottom separately but thats wrong.

#

I think.

long arch
#

idk how to explain it what background knowledge do you have

#

can you do u substitutions and stuff

vagrant mural
#

I could but I'm bad

#

So the du for c would be the denominator?

long arch
#

let u = the denominator for part b and solve from there

vagrant mural
long arch
#

gimme a sec to do it

vagrant mural
#

Ok thank you very much

long arch
marsh citrusBOT
#

@vagrant mural Has your question been resolved?

vagrant mural
#

How can u get logs in there?

long arch
#

integral of 1/u is ln(u)

vagrant mural
#

Nice

#

Thanks

#

.Close

#

.close

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ornate dragon
#

How to calculate this with mean value theorem I know it's a Riemann series and there is well definite methods to this but I want to use the theorem.

ornate dragon
plush elk
#

It doesn’t converge

#

$\frac{1}{k+n} \geq \int_{n}^{n+1} \frac{1}{k+x} dx=In(k+n+1)-In(k+n)$ so choose any integer m greater than k, the sum of first n terms is greater than sum of first m terms +In(k+n)-In(k+m) it goes to infinity when n approaches infinity.

elfin berryBOT
#

Cogwheels of the mind

ornate dragon
#

tnx so much so the intervall is [k, k+1] an the function is f(x)=ln(x+n)

plush elk
#

Better not use the same symbol

#

When the interval is [n,n+1] the function is 1/(x+k)

dry trail
#

Seeing it as a Riemann sum, it appears to converge though, mmm what is happening?

plush elk
#

?

#

It doesn’t

dry trail
#

The sum is from k=0 to n right?

plush elk
#

You replace n with n^s, it converges iff n>1

plush elk
dry trail
#

Mmm but I think the sum is on k

plush elk
#

Unless positive infinity count as answer

#

Shit…

#

I was so dumb

#

In(2) right?

ornate dragon
#

yes

dry trail
#

Yeah that is what I thought as well

plush elk
#

$\int_{n}^{2n+1} \frac{1}{x} dx \leq$ that sum $\leq \int_{n-1}^{2n} \frac{1}{x} dx$

elfin berryBOT
#

Cogwheels of the mind

ornate dragon
#

you used the rectangle method?

plush elk
#

So $In(\frac{2n+1}{n})\leq$ that sum $\leq In(\frac{2n}{n-1})$

elfin berryBOT
#

Cogwheels of the mind

plush elk
#

Then take limit of all

plush elk
elfin berryBOT
#

Cogwheels of the mind

ornate dragon
#

ok tnx

#

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worthy owl
#

really quickly. do u put restrictions on the numerator? (operations on rational expressions)

burnt abyss
#

nope

#

just the denominator needs to be ≠0

worthy owl
#

thank you!!

burnt abyss
#

np

tacit trail
#

I meantheres case like

#

$$\frac{\frac{a}{b}}{c}$$
c ≠ 0
b ≠ 0

elfin berryBOT
#

Pluton

tacit trail
#

But thats still denominator

marsh citrusBOT
#

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stark knoll
marsh citrusBOT
stark knoll
#

Obtain the range of the function....

#

I was trying to figure this by myself

#

And everything was okay... I am not on my house so i cannot show the procedure that I took...

#

But I thought something like... try to just leave the X on RHS....

#

And to get rid of that annoying square root of the bottom... I elevated everything to the square... but I couldnt solve the entire thing...

#

So... is there a better method or something that works for everything or it is just that my knowledge didnt let me solve the entire thing but my procedure was correct?

#

I also tried other things like factorizing some terms and expressing everything like a two variable quadratic ecuation.... but nothing worked

#

I am fine with just being shown the way

#

Of... quitting safely a square root from the denominator

#

quitting -> getting rid of, sorry idk english

marsh citrusBOT
#

@stark knoll Has your question been resolved?

civic moss
#

Hm

stark knoll
#

In all my tries I always finished with x = some thing with a trinomium on the denominator that has an -x on it

civic moss
#

@stark knoll couldn’t you just reason through this one

#

You can’t plug in any x that is -3 or lower

#

At -2.999 it’s -5.9/0.00001 which approaches -infinity

#

And as x approaches infinity, the function becomes sqrt(x) which goes to infinity

#

So the range would be (-inf, inf)

#

But I’m sure a lot of that reasoning didn’t make sense lol @stark knoll

stark knoll
#

hmmmm

#

Yeah I understand

#

I was searching for a more algebrai... Idk english... A way just using algebra things, ik I could just graph the thing or try values... but if there isnt a clear way I suppose we can close the case

#

thx u so much anyways @civic moss !! <3

#

If u for any reason come out with something while sleeping or something like that because those things happen... lmk

#

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Please don't occupy multiple help channels.

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oak fern
#

I would like to compute this :

marsh citrusBOT
oak fern
#

$\lim_{n \to \infty} \frac{1}{n} \sum_{k=1}^{n} ln(1+\frac{k}{n})$

elfin berryBOT
cunning citrus
#

what have you tried?

oak fern
#

I was thinking about using limit sum inversion

#

So I need to prove the uniform convergence

noble nebula
#

Where is Riemann when you need him

oak fern
#

Riemann for ln as f and (0,1) for (a,b)

noble nebula
#

If by ln you mean ln(x), no

oak fern
#

Arh

noble nebula
#

But very close.

oak fern
#

ln(x+1)

noble nebula
#

from 0 to 1. That's how I would do it.

oak fern
#

Okay I’ll try

#

Thanks

#

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opaque seal
#

Can someone explain to me how to get the answer of 54.3 in question b and 26 in question c

opaque seal
#

<@&286206848099549185>

marsh citrusBOT
#

@opaque seal Has your question been resolved?

opaque seal
#

<@&286206848099549185>

mystic minnow
# opaque seal

the farmers are supplying 31 million liters. They are selling all of those liters (either to people or the government) at a price of 1.75
Revenue = price x number sold

marsh citrusBOT
#

@opaque seal Has your question been resolved?

opaque seal
#

@mystic minnow Ty sm! What about question c)?

mystic minnow
opaque seal
#

@mystic minnow omg sorry for asking dumb questions. I’m just reviewing my old assignments and I forgot how to calculate it. It sucks that it doesn’t show solutions

mystic minnow
opaque seal
#

@mystic minnow God bless you🙏🏻🙏🏻🙏🏻

feral relic
#

Pls tell the answer for this question plsss

#

<@&286206848099549185> pls

#

Hello

mystic minnow
feral relic
#

Why?

mystic minnow
feral relic
#

I can't open my own channel

#

After seeing how to get help

#

Zybikron

mystic minnow
#

• Pick a channel in the “Available” section and post your problem. The bot will move your channel to the “Occupied” section, and the channel will be reserved for you until your question is answered. Stick to one channel and don't post the same question in multiple channels. Don't ask for help in other channels if no one is responding in the one you have posted your question in.

feral relic
#

I can't understand that

#

What should I do

sour relic
#

go to available math help channels

#

occupy one

feral relic
#

How to occupy?

#

It is telling you don't have permission

sour relic
#

???

feral relic
#

To send messages

sour relic
#

send screenshot

feral relic
sour relic
#

dude these are math help hidden

#

I said math help available

feral relic
#

Send screenshot pls

mystic minnow
sour relic
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gentle willow
#

It's an equilateral triangle.
How to prove ∠Q1 = ∠Q2 = 60
And ∠B1 = ∠B2 = 30

gentle willow
#

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deep fossil
#

for this problem

marsh citrusBOT
deep fossil
#

should I just use the half angle formula for tan

#

oh no

next ravine
#

cos(x/2) = ?

deep fossil
#

or I make the reference triangle and use the half angle of cosine

deep fossil
#

so would it be cos(sqrt1+12/13over2)

next ravine
#

I haven't done the problem yet, but if you show work and every step then I can look

deep fossil
#

okay:)

#

look right?

next ravine
#

yup

deep fossil
#

awesome!:) I get it now thanks for your help I just hadnt done a problem like that yet

#

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feral relic
#

Hello

marsh citrusBOT
fickle fractal
#

?

feral relic
#

Hello

fickle fractal
#

erm

#

what help you need?

feral relic
#

Do you solve my help?

fickle fractal
#

well what is your problem in maths?

feral relic
#

This is pls solve

fickle fractal
#

are we trying to find D or x?

#

WTF

feral relic
#

We want to find the general solution

marsh citrusBOT
#

@feral relic Has your question been resolved?

plush elk
#

You write cos(x) as (e^ix+e-ix)/2

#

Then use a formula

#

$P(D)(e^{λx}u(x))=e^{λx}P(D+λI)(u(x))$

elfin berryBOT
#

Cogwheels of the mind

plush elk
#

Where P is a polynomial, D and I are two operators: D(f(x))=f’(x), I(f(x))=f(x)

whole sleet
#

What is D4 supposed to be?

#

Is that D⁴?

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shy hill
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vivid axle
#

Hiya peeps!

Anyone able to help me with this binomial expansion Q. Struggling to well...expand it to put it simply. Looking at past examples, they make sense but this one isn't clicking as quickly as the others. Mostly down to the power.

I've attempted to make a >= 0 by just making it (a+1)^1/n and then using the binomial expansion but it's not exactly clicking as to...well...getting the final answer. Would appreciate the help!

marsh citrusBOT
#

@vivid axle Has your question been resolved?

marsh citrusBOT
#

@vivid axle Has your question been resolved?

plucky shoal
elfin berryBOT
#

1345631

vivid axle
#

So that's using the hint. But do we not need to derive 1+(a-1)/n from a^1/n at all?

plucky shoal
# vivid axle So that's using the hint. But do we not need to derive 1+(a-1)/n from a^1/n at a...

No. We do not need to derive it. Here is some more detail. For 8 marks, we would need to say:
Let $a \in \mathbb{R}$ with $a \geq 1$ be arbitrary and let $n \in \mathbb{N}$ be arbitrary. Now, note that both $a^{1/n} \geq 0$ and $1 + \dfrac{a-1}{n} \geq 0$. Thus, we can apply the hint.

The point is that we don't know that the inequality printed holds. But it being true is equivalent to the second line I wrote above being true, by the hint. Then, by Bernoulli's inequality, we reach $a \leq a$, which is true. So then, we can start from the last line, and go back the reverse way. In our answer we just present the answer in the reverse way to present a logically sound argument.

elfin berryBOT
#

1345631

vivid axle
#

I'm surprised that there was no need to derive it, as in lecture we've used the binomial expansion in order to get a term that (once completed with the algebra of limits) tends to a value

#

But I'll take it if it's that simple, but the question as a whole is 8 marks, theres one other part using the sandwich (or squeeze) theorem below

plucky shoal
# vivid axle But I'll take it if it's that simple, but the question as a whole is 8 marks, th...

You can make your solution more complicated so that you can be more confident that you obtain all marking points. For example, do not apply Bernoulli's inequality (note: this is derived from the Binomial theorem). Instead, use the Binomial theorem itself, and then derive the fact that Bernoulli's inequality holds from that.

You can start from (1+ (a-1)/n)^n = ... [apply Binomial theorem]
Truncate some terms, which are all non-negative, to get (1 + (a-1)/n)^n >= a.
Use the hint.

If you look carefully, this is just the logic I presented above, but in the reverse way. I hope this can help elucidate the question a bit more.

vivid axle
#

That makes sense now that you've explained it in a lot more detail than I was expecting lol

Now onto the next part of the question...to see if I can actually solve the sandwich theorem.

Thanks for the help!

plucky shoal
vivid axle
#

No need to apologise for explaining it too much, means that I can see every step that you've taken rather than being left in the dark (I already experience that enough in further applied maths)

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still temple
marsh citrusBOT
still temple
#

How can I approach this???

#

I'm pretty lost

#

Distance usually to me means some point minus another one

trail flare
#

Fine the equation of the line

#

Then find a general form for the vector between the line and point

#

And consider the fact that must be perpendicular to the direction vector of the line

#

(I would check if the point lies on the line first honestly)

still temple
#

Is this right?

#

I'll get the cross product, then divide by the norm of u

still temple
trail flare
# still temple For ur attention

Personally I think the best way is to write a general eqn of the line (in one vector) and then the scalar product of that and the direction vector is 0

#

That lets you solve for t which essentially solves the problem

still temple
#

So I'm teaching myself here.....

#

Ah NM. I'm done for a bit

#

I'm more confused rn lol

#

Tyty

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marble lodge
#

I need help with this

marsh citrusBOT
marble lodge
#

I tried making a matrix and tried solving it with the conditions given but idk how to proceed

#

all I know is the dimension for a slew symmetric matrix is n(n-1)/2 but i don’t think that will work here

wind wadi
marble lodge
#

i’ll dm u

wind wadi
#

Especially, what kind of structure does it need to have to satisfy A^T = -A?

marble lodge
#

it’s a skew symmetric matrix

#

so all the diagonals are gonna be 0

#

and aij = -aji

wind wadi
#

yes

marble lodge
#

so what do i do

wind wadi
#

then to find a basis you can try to row reduce it

marsh citrusBOT
#

@marble lodge Has your question been resolved?

marble lodge
brittle anchor
#

marsh citrusBOT
#

@marble lodge Has your question been resolved?

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still temple
#

hi.. can someone help me please: for question number 3

still temple
#

this is what i have so far:

#

im stuck on the regions increasing/decreasing, regions concave up and down part

#

thanks in advance

twin girder
#

For increasing/decreasing just solve log(x)+1>=0?

still temple
#

i got x>1/10

#

is that right

#

and what would i put on the number line?

twin girder
#

Not 1/10 no

still temple
#

i searched up the answer on google and said that its Increasing on: (1/e, infinity) and decreasing on (0, 1/e)

twin girder
#

Indeed

still temple
#

but i have no idea how they found that

#

like idk what i should do to get the answer

twin girder
#

That is the derivative you found?

still temple
#

so do i just make the derivative = 0?

#

i did that and then got x=1/e

twin girder
#

That works since continious, yes

#

Now you need to check a value above and below 1/e to figure out sign

still temple
#

was the number line i drew above correct? or should i only have 1/e and -1/e on it?

#

also can i input -1 for the value that is below 1/e

twin girder
#

What number line?

twin girder
still temple
still temple
twin girder
#

Any value greater than 1/e

#

And any value less than 1/e

still temple
twin girder
#

Yeah no idea what that is supposed to do

still temple
#

okay so i put 2 for the value greater than 1/e and got a positive number

twin girder
#

You only need a single

#

Like I said

#

And a single value less than 1/e

still temple
still temple
twin girder
twin girder
still temple
twin girder
#

Oh sure

still temple
#

like i did this: f(2) = In(2) +1

still temple
#

idk what to use for the value thats less than 1/e

#

hello?\

twin girder
#

A value less than 1/e

#

And ofc you need your function to be defined

still temple
#

ik but what number could i use idk what a value is less than 1/e

twin girder
#

What about 1/10000000000

#

Or whatever

#

There are inf amount of numbers less than 1/e

still temple
#

okay i got a negative number as the result

#

now what

twin girder
#

What does it mean for derivative to be negative?

still temple
#

that its decreasing

#

i think

twin girder
#

Indeed

#

Since our derivative is continious it is less than 0 for all values in (0,1/e)

still temple
#

ohh

#

so basically thats the region its decreasing on

twin girder
#

Yes

still temple
#

so do i say that the derivative is decreasing or that the function is decreasing

twin girder
#

The function is decreasing at a point if its derivative at said point is less than 0

still temple
#

ohhh okok

#

how can i solve the concvity

twin girder
#

Exact same idea as you just did

still temple
#

.close

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kind echo
#

hi

marsh citrusBOT
kind echo
#

trying to figure out how 6/2:7/3:8/4 became 9:7:6

twin girder
#

Multiply num in them all by 3

kind echo
twin girder
#

Because now they are all integers

kind echo
twin girder
#

7/3 not an integer

#

Multiply by 3 and it is

kind echo
#

ohhh

#

but we can multiply with any number then?

twin girder
#

Yes

#

2:1 same as 4:2

#

2nd one is just 1st multiplied by 2

kind echo
#

yes true

#

okay i get it

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fluid talon
#

hello im working on a math project and im being asked to get the height of a pile and the only information I have on the pile is the angle of repose and the density of it any help? 35° and 90lb/ft^3

marsh citrusBOT
#

@fluid talon Has your question been resolved?

fluid talon
#

<@&286206848099549185>

#

okay so all ive gotten now i have to set up a trig function but i dont know how to solve it for height

#

Tan 35° = X/20

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shut wadi
#

howdyyy, does anyone know how to find the perimeter/area of parameterized surfaces? the problem specifically is:

"Suppose a surface has fundamental form I = du^2 + (u2+a2) dv^2 (constant a). Consider a triangle bounded by u = av, u = -av, v = 1.
a. Find its perimeter.
b. Find its area."

subject: differential geometry/tensors

shut wadi
#

my first thought was line integral over the square root of the first fundamental form, but i don't know what z' would be in this case

elfin berryBOT
#

ashreaver

marsh citrusBOT
#

@shut wadi Has your question been resolved?

shut wadi
#

<@&286206848099549185> hi hi, i have a differential geometry question

shut wadi
fluid meteor
#

not quite sure if its the correct way, but maybe try to calculate your metric tensor.

#

you than have to take the squareroot if the determinant of this tensor. Put your parameterization into f.

#

I guess f will be I here, and multiply I(parameterization)* the squareroot

#

Integrate this product and this is your surface integral. At least if your surface is 2 dimensional and lives in 3 dimensions. I assume that is the case here

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#

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old sable
marsh citrusBOT
old sable
#

what'll be the reasoning that is necessary to set up the ODE?

still temple
#

well at any time t the net acceleration of the rocket ( the rate of change of velocity) is dependent on t (the time passed in seconds from launch) as 7t m/sec^2

#

therefore dv/dt = 7t

old sable
#

I get that and arrived at this $$\frac{7t^3}{6} + c_1 t + c_2 $$. But now what?

elfin berryBOT
still temple
#

wait did you integrate twice?

#

this is displacement as a function of time right?

old sable
#

I don't this the question gives me enough information to calculate $c1$ and $c2$.
Yes, I just integrated it twice

elfin berryBOT
still temple
#

I get what you're saying

#

but you're doing an indefinite integration

#

you need to do a definite integration or at t = 0 the velocity is also zero so you get c1 = 0 from there

crystal wraith
#

$\frac{dv}{dt} = a$\
\
$dv = adt$\

$\int_0^v{dv} = \int_0^{10}{7t}dt$

still temple
#

and also at t = 0 the displacement ( in this case height ) from the ground is also zero therefore c2=0 as well

crystal wraith
#

Something like this.

still temple
#

dv = adt

crystal wraith
#

Yes...

#

Mb

still temple
#

now take the limits as shown in the photo

elfin berryBOT
#

What the hell am I doing here?

still temple
#

but also hiro there are 2 parts

crystal wraith
#

Yes, this is just a way you should start.

still temple
#

first you gotta integrate this twice to get how high it reaches until the engine stops

#

and then you can use the pre existing 0 = U^2 - 2gS and solve for S

#

where S is extra height travelled after reaching the point where the engine is turned off

old sable
#

💡 Got it!

still temple
#

and U is the velocity at that point

old sable
#

Thanks guys

still temple
#

NP bro

old sable
#

Phew, just setting up the ODE is the most of the weightlifting xD

still temple
#

do you need to setup one equation for both the situations?

old sable
#

I'm good. It's the general feeling whenever I sit down to practice ODEs

still temple
#

Yeah, well wait until you encounter PDE's

old sable
#

.close

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distant meadow
#

what is this 3n−7−(−n−6)

marsh citrusBOT
distant meadow
#

3n−7−(−n−6)

novel fjord
#

an expression

distant meadow
#

does it have a end

novel fjord
#

what

distant meadow
#

is there an answer

#

whats 3n

novel fjord
#

a term

distant meadow
#

coul d 3n be 30

novel fjord
#

if n=10

distant meadow
#

then it would be 30?

novel fjord
#

if n=10

#

n is just a variable

distant meadow
#

310

novel fjord
#

if you're not given a value for n, keep it as a variable

distant meadow
#

yea

novel fjord
#

are you just looking to simplify the expression?

distant meadow
#

yea

novel fjord
#

cause unless you're told that n = something, your simplification is gonna be in terms of n

#

you just need to distribute the negative and combine like terms

distant meadow
#

i see

#

ok

sour basin
#

Do you know -(-x) =x

marsh citrusBOT
#

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young mirage
#

does anyone know how to do this?

marsh citrusBOT
young mirage
#

I am trying surface integrals

#

but idk how to continue with this

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hazy lion
marsh citrusBOT
hazy lion
#

so I am not confused by the problem so much as the mechanics

#

i feel this should be straightforward but im choking a little on the exact method

#

any hints?

gloomy zealot
#

no idea what any of that even is mate, but surely u can multiply it by 0 to have a predictable value

marsh citrusBOT
#

@hazy lion Has your question been resolved?

hazy lion
#

<@&286206848099549185>

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marsh citrusBOT
marsh citrusBOT
#

@foggy trail Has your question been resolved?

inner acorn
#

am i allowed to ask question in here?

proper zodiac
inner acorn
#

thanks

marsh citrusBOT
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queen pelican
marsh citrusBOT
queen pelican
#

just need a brief explanation

#

of what it'd be

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@queen pelican Has your question been resolved?

marsh citrusBOT
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@queen pelican Has your question been resolved?

queen pelican
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.close

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merry ivy
marsh citrusBOT
merry ivy
#

I’m not sure if I did my math right

#

<@&286206848099549185>

marsh citrusBOT
#

@merry ivy Has your question been resolved?

dreamy trench
#

,w ((3,5,0),(8,-23,0),(-2,5,25)) (x,y,z)^T = (0,0,0)^T

#

I need a column vector lmao

proper zodiac
#

,w row echelon {{3,5,0},{8,-23,-109},{-2,5,25}}

#

Wolfy for some reason likes braces for matrices

dreamy trench
#

Ah that makes sense

proper zodiac
#

Oh you copied matrix wrong lol

merry ivy
#

that doesn't look like my matrix. do you where i messed up?

smoky siren
#

It would have been cleaner imo if you started with R_1 + R_3 -> R_1

merry ivy
#

like at the beginning?