#help-38

1 messages · Page 89 of 1

tribal jetty
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prob this image is easier to understand idk

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if you have seen physics

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is the same logic

torpid moat
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No I understand it

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the different graphs really helped!

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thanks sm!

tribal jetty
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ok

torpid moat
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torn ether
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how should I solve this. I honestly have no clue where to start

wanton rune
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seems like a trig-sub integral

torn ether
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I think so based on my teachers notes but Ive never done one like this

wanton rune
round mango
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There's a 2/z³ outside, I'd start by letting 1/z²=u

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Multiply and divide by -1 first to form du at the top

wanton rune
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huh

torn ether
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??

wanton rune
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ah

round mango
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1/z²=u

wanton rune
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i see

round mango
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=> -2/z³=du/dz

wanton rune
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it may be better to let u=sqrt(x^2-1)

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hmm nah

torn ether
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im so lost rn

round mango
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Should get you somewhere

torn ether
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sorry I just don't get this one

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long iris
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Sorry

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My bad

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stiff briar
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i need help on 52 😭

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stiff briar
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i'm not sure if it's oscillating or not

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but it converges to two values

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0 and 2

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so is that considered oscillating

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and therefore diverging

jagged fiber
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yes ur correct

stiff briar
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okay thanks

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jagged fiber
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np

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ocean lake
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Hello! This is not a math related topic but i was wondering about how the availability bot and channels are made? I would like to do something similar in one of my study servers

sly pewter
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not the person who made the bot but you can probably just add the bot to your server

ocean lake
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may i know how?

sly pewter
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hmm i couldn't find it in the app directory

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but you can use a ticket bot

ocean lake
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and it would do the same function?

sly pewter
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it would be similar

austere cedar
sly pewter
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ok cool 🤩

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do that

austere cedar
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That's the github. Not necessarily how you might actually add it to a server.

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I am not certain myself

ocean lake
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yea that was my next question lol

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i'll try out a ticket bot since i cant download this one.. but thanks for your help!

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tropic sequoia
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How to solve this do I make the denominator the same?

tropic sequoia
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tropic sequoia
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tropic sequoia
tranquil widget
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isolate the x’s by splitting the numerators

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Or find a common denominator

tropic sequoia
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odd spear
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is the region from 1 to y the same as y to 1 for an integral?

odd spear
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verbal nebula
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verbal nebula
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tried changing all to common bases in the expression t3-t2=t2-t1 but it got messy

gritty harness
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write all of them with the base k using this rule

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then try to simplify

verbal nebula
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i got 2/log_k(m)=1+1/log_k(n)

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orchid wagon
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explain like im 5, when we say function f: A -> B, what does A and B mean?

marble wharf
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sets

orchid wagon
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elaborate?

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ive never seen this notation ever in my hs curriculum, yet it seems so prevalent in american hs

marble wharf
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A, B are sets. A is the domain of the function f and B is the codomain

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f takes inputs from the set A and gives outputs from the set B

orchid wagon
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so A is the domain of the func, and B is the range?

marble wharf
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no

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range and codomain are not the same thing

fathom ivy
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A: all valid inputs
B: all things that you think has a chance of being the output

for example if i define a function and call it shredder

i might have shredder: {paper, printed letters im not gonna read, some idiot’s laptop} -> {shredded paper, shredded letters, the shredder catches fire, the universe explodes}

and we can assign a mapping:
shredder(paper) = shredded paper
shredder(letter) = shredded letter
shredder(some idiot’s laptop)=shredder catches fire

note that nothing maps to the universe explodes, not everything in the codomain must have something map to it

orchid wagon
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so codomain is just range, except its not reliable?

fathom ivy
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it always contains the range, but sometimes the function is so not well understood that it might contain extra stuff

orchid wagon
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so it must contain the range

fathom ivy
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a silly example is f: R -> {0, 1}, where

f(x) = 1 for all x if we establish contact with aliens in the next 50 years

f(x)=0 for all x if we don’t

marble wharf
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and its just generally easier to be able to say f:R->R and not worry about the actual range of f for now

orchid wagon
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makes sense

marble wharf
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you are just saying: f takes as input a real number and produces a real number as output

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which numbers it can actually output (aka the range) is not important yet at that point

orchid wagon
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alright i think i get it now

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thanks

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sage harness
#

A light house of height 53m stands on horizontal ground level with the base of a 80m cliff. The angle of elevation of the top of the cliff from the top of the light house is 27 degrees. Calculate theangle of depression of the base of the cliff when viewed from the top of the light house, leaving your answers to 1 decimal place.

sage harness
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i just dont get how it would look like so could somebody draw a diagram for me?

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sage harness
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<@&286206848099549185>

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distant abyss
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hello! I need help on number 3

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devout drift
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What have you tried?

distant abyss
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Through the set operation, i used
n[(C n E n J) U (C n J n E^c) U (C n E n J^c) U (E n J n C^c)]

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I used venn diagram to come up with that notation

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After expanding

devout drift
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It will be easier to understand with the venn diagram

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Can I see the venn diagram

distant abyss
distant abyss
# distant abyss After expanding

I used the venn diagram again to cancel out the mutual exclusives (which is not a formal proof sadly), and after all that I was left with

n (C n E n J) + n (C n J n E^c) + n (C n J^c n E) + n (C^c n J n E)

devout drift
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I meant with the elements of the sets as well (for example how many eat in caffeine) those you have already found out right?

distant abyss
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so 42 + (126 - 42) + (112 - 42) = 196

devout drift
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You don't expect me to solve this all over again just for last part when you already have that information sully

distant abyss
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But how am i supposed to get number 3 tho from number 1

devout drift
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I don't know just show me the elements

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For now

distant abyss
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uhh number 1 is n [ C n (E U J)^c] = 112

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number 2 is 0

devout drift
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Nvm

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I'll just do it

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Wait 10 hours

distant abyss
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damn.

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distant abyss
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hello @devout drift are you still on it and willing to continue?

distant abyss
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C= Caffeine, E = Express, J = Joe

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n(C) = 308
n(E) = 238
n(J) = 504
n(C n E) = 112
n(C n J) = 126
n (E n J) = 42
n ( C n E n J) = 42

distant abyss
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mb i think im too late on that now

devout drift
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You made me find all the elements

distant abyss
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i am so sorry

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im incredibly slow

devout drift
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Your first part is correct

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Last one imma check

distant abyss
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okay, thank you sm

devout drift
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It's correct

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You did

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number of elements in exactly two sets + number of elements in all three sets correct?

distant abyss
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yeah

devout drift
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It's correct

distant abyss
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alright, but how did you do it?

devout drift
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This would have been fast with all those elements

distant abyss
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im just not sure since my solution involved using venn diagrams to determine those which are mutually exclusive, and im kinda sure that my professor does not find that rigorous or sumn

devout drift
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$n(C \cap E) + n(C \cap J) + n(J \cap E) - 3n(C \cap J \cap E) + n(C \cap J \cap E)$

solid kilnBOT
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ColdTee

devout drift
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Basically

devout drift
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For questions like these

distant abyss
# devout drift I find set operations easier sometimes

i did use set operations, but when i expanded, some terms like n[ (C n E n J) n (C n J n E^c) ] came up, and since i dont know any properties i can use to get an answer, i used venn diagram instead, and it showed me that they;re exclusive

distant abyss
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you headed directly for the ones with the arithmetic

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based on how my prof taught it, she wants us to denote the thing being asked for in n(X) of something

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then use properties to expand, blah blah blah

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i think i shudve went with that instead

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thanks so much for the time and energy spent @devout drift

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red jolt
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doing it for 5th time now and still can’t solve it. what am i doing wrong here?

brazen forge
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arent you overcomplicating this?

digital bolt
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a-sqrt(y-a)

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the one you're integrating is like the right side of the parabola

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whereas you want the left

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if you think about it, sqrt(y - a) + a will never touch the y-axis

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you want a - sqrt(y-a)

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to match the graph

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but also yes you are overcomplicating this

brazen forge
digital bolt
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just integrate wrt. x to get S+T and then subtract a^2 to get S

brazen forge
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you should find a with this info alone

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dx in integral ofc

red jolt
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oh for real

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thanks for helping guys

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i’m not good at understanding integral

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quick hound
#

if i do trigonmetric sbustitutin with this

quick hound
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i tried complete the square

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and this what i get

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what do i even sub with this??

rough goblet
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x - 4?

quick hound
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really?

rough goblet
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idk

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i dont have much intuition for ints

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gimme a moment

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hm

patent crow
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that leaves you with a sqrt(8u^2+2) integral

quick hound
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it has to be a trigonemtric thing

rough goblet
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yea ik

proven sluice
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Do u know standard integrations of such function?

rough goblet
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am dum lmao

quick hound
proven sluice
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Int of √x²+a²

quick hound
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like the other functions

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the subs were pretty self epxlenatory

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but this one is weird

quick hound
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but its not x^2-a^2 form here

proven sluice
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That's when it's in denominator

quick hound
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oh

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different in nominator?

proven sluice
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Yeah

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It's much longer

quick hound
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uh oh

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do u know the name?

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or still trigonemtric substitution

proven sluice
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Wait

proven hound
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,calc 16*8

solid kilnBOT
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Result:

128
quick hound
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oh is it -2

proven hound
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Ye

quick hound
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still dont know how to tdo the mian part;-;

heady lava
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take out sqrt(2) maybe

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so the inside becomes 4(x-4)^2-1, idk if that actually helps tho

quick hound
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i dont know what to do with it afterwards

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is the problem

proven sluice
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Use these

quick hound
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oo

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thanks

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whats this called?

heady lava
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might be stupid, what if
(x-4) sqrt(4(x-4)^2-1) + 4 sqrt(4(x-4)^2-1)

proven hound
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There's an x outside though

proven sluice
quick hound
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yeah

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i needa know the proof

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im gonna google it

proven sluice
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That's long , sure u can

heady lava
proven sluice
heady lava
proven sluice
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By parts maybe?

quick hound
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it has to involve

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some sort of trognmeitc sub

proven sluice
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Yeah

quick hound
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i dont know what it is

proven sluice
quick hound
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how do i remove the -64x

proven sluice
proven hound
proven sluice
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And it's dt is 2x

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So it's solvable ig

heady lava
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lol

proven hound
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Lol

heady lava
quick hound
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if i do that using x^2 sub is easier

proven sluice
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Cuz then x will be root t

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Much more difficult

quick hound
#

Video #4 on the method of Trigonometric Substitution, showing how completing the square can also be used to help solve these problems, converting a quadratic polynomial into one that can be used for trigonometric substitution.

Full Playlist of Calculus 2 Videos: https://www.youtube.com/playlist?list=PLbKymuaXja98kMr9eknYG23-dgnRaelR1

This was...

▶ Play video
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mighve found it

charred trail
quick hound
#

no

charred trail
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no like because when completing the square you get something (x-4)^2 or whatever, so let t = x-4, i.e. x = t+4

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unless im getting confused

heady lava
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although it tends to use stupid methods sometimes

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the antiderivative is a heck of an expression btw

quick hound
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yeah

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im trying to make it into integration form

quick hound
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look at this guy

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hemade the complete the square

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by making the inside of the square

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into smth else

heady lava
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yeah but in this case it's very hard to find a good substitution

quick hound
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then using the shit outside as like a trigonemtric sub

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lemme cook i have an ideda

charred trail
quick hound
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what trig substitution

heady lava
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judging from the integral calculator result, it would be absolutely insane if there was a trig sub for this

charred trail
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if the integral does come to the form of some sqrt(8u^2+2) or whatever it is, probs best to use the fact that sec^2(x) = tan^2(x) + 1

quick hound
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ye

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im trying

heady lava
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oh I see

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also it's sqrt(8(x-4)²-2), so it should be ||x=sec(theta)/2 + 4||

quick hound
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GOT IT

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oh

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you guys got it too

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nice 😄

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ok thank god for that yt vid

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that was hard to wrap around

proven sluice
heady lava
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I keep forgetting you can just add random constants to the trig sub lol

proven sluice
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Ok nice lol

quick hound
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ok trying the next one

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ok so this one i use sin

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i think

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use 1-sin^2(x)

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ok nice got it

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thanks for the help guys

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how do i integrrate tan^2x

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nvm i did it

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but i got smth wrong somewhere else

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viscid pagoda
#

Como eu posso práticar mais matemática, tipo eu assisto uma aula sobre frações, e depois de um tempo eu vejo que frações é muito mais aprofundado do que aquilo que eu pensava, o que eu faço?
Experiência? Tentativa e erro? Eu vim aqui para poder perguntar para vocês que obviamente estão a milhares de kilometros a minha frente, por favor alguem poderia me ajudar nisso?

worthy eagle
#

translate it for us

fathom gull
#

How can I practice more math, like I watch a class on fractions, and after a while I see that fractions are much more in-depth than what I thought, what do I do?
Experience? Trial and error? I came here so I could ask you who are obviously thousands of kilometers ahead of me, could someone please help me with this?

google translate

worthy eagle
#

maybe if you can show an example I'd be appreciate it

viscid pagoda
#

Sorry, I understand English, I just asked the question on the wrong server

worthy eagle
#

no worries

viscid pagoda
#

what can I do?

worthy eagle
#

that's what I asked

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I dont usually get "like I watch a class on fractions, and after a while I see that...depth than what I thought"

viscid pagoda
#

Relax, I managed to think of something here, thank you very much

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#

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blazing socket
#

I have this example problem that my instructor didn't get to finish in class, could someone explain where the csc comes from in the second to last step?

fierce bay
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yes

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its just the coefficient sec/tan factored into tan^2+1 and simplified

vagrant marsh
#

in line 5 you also need to divide the tan to the 1

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oh

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i see, this is a poorly written solution

blazing socket
#

yea my instructor was running low on time and tried to get it done as quickly as possible 😭

vagrant marsh
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sec/tan simplifies to csc

#

when multiplying sec/tan with tan^2, you get sec*tan, and multiplying sec/tan with 1, you still get sec/tan which you can simplify

blazing socket
#

ahh gotcha

#

i've got it figured out now, thank y'all :)

#

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vagrant marsh
#

yw

blazing socket
#

.reopen

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#

blazing socket
#

i'm now attempting to finish the problem myself and i have no idea how to get back to x terms from here 🗿

#

do i need to get all of these trig functions into the form of tan theta to convert it back?

craggy sage
#

u can make a right angle triangle in which one angle is theta and side oppo to it is x and adjacent to it is 1 and hypotenuse is root(1+x2) and then write the ratios

blazing socket
#

ohh gotcha

#

ty

knotty locust
#

Yes when you did the sub x=tan(theta) remember what that tells you

#

Using SOHCAHTOA to form the triangle

blazing socket
#

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blazing socket
#

i've got another problem now, and i'm not sure how to choose which trig function to use

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full dock
#

No idea how to integrate this thing

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frozen plover
#

right path

#

Do a + 1 - 1 in the numerator

#

split the fraction

#

x^2 + 1 and x^2 - 1

#

then divide both fractions numerators and deniminators by x^2 and complete the square appropriately

full dock
#

Okay I’ll try that

frozen plover
#

this is gonna get a little nasty

#

you have been warned

full dock
#

I saw the answer for the integral and I’m already scared

frozen plover
#

haha

full dock
#

Is this what you mean

#

For the split

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tribal fractal
#

for this question, the derivative does not exist at x = 0

tribal fractal
#

is that enough to say why the formula doesnt work?

#

it has a discontinuity

tribal fractal
#

thanks

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marble vault
#

How would I find the percentage of the triangle that doesn't contain the circle

sly pewter
#

Where are you at right now

marble vault
#

My house

sly pewter
#

Like where are you at in the problem lol

marble vault
#

Lol i was gonna find the area of the circle and then after that find the heighrt of the triangle so i can find the area of it and then subtract the area of the circle from the triangle and get a percent

#

But im not sure how to fully find the area of this circle

#

Im in 9th grade btw so this is prob like a stupid easy question for u lol

sly pewter
#

There must be some geometry rule about circles being inside a triangle

#

I did geometry in 8th grade and it went by so fast 😭 let me see

marble vault
#

Damn thats impressive bro nice work

sly pewter
#

Not impressive if you can’t maintain

placid juniper
#

radius = 2 x area of triangle / perimeter of triangle

sly pewter
#

Real formula

marble vault
#

how do i find the area of the triangle though

#

i dont have a height

#

can i juse use herons?

sly pewter
placid juniper
#

idk i made it up

marble vault
#

🔥🔥🔥

placid juniper
#

no too complicated

#

did u get that off chat gbt

marble vault
#

no we learned it in class dawg

#

now how do i find the circle

placid juniper
sly pewter
#

Oh use the tangible line rule

#

Tangent

#

Two tangent

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marble vault
#

.reopen

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marble vault
#

@sly pewter how do i use two tangent if it isnt a right isoceles

#

im a little confused

#

and @placid juniper in the vid i sent u the way he does it isnt possible without right isoceles

#

also i had to redraw the triangle got new area as 22.27

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distant bay
#

HELPERS IN 31

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Please don't occupy multiple help channels.

distant bay
#

HELP

worthy eagle
#

!1c

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Please stick to your channel.

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rain light
#

Can someone help me with this?

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gaunt wave
#

So the sides are going to be equal

#

for the upper one, the hypotenuses are going to be equal

#

and the other sides are going to be equal assuming they are the respective sides

#

@rain light

rain light
#

Yeah

gaunt wave
#

Does what is above make sense?

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distant bay
#

help

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distant bay
burnt mulch
#

Where’s the question

distant bay
#

nevermind

#

new question

#

Pls help

#

<@&286206848099549185>

distant bay
candid roost
#

what do you need help with?

distant bay
#

This question

candid roost
#

The last one you posted, the image.

distant bay
#

Yes

candid roost
#

okay give me a sec to figure it out.

#

I think you just find the area of a rectangle then subtract the area of a triangle.

#

What do you think?

distant bay
#

Idk

#

i think you add instead

candid roost
#

Find the area of the rectangle first then subtract the triangle.

distant bay
#

I got it wrong

candid roost
#

Give me a sec to run a calculation on it.

split chasm
#

show your work

candid roost
#

Okay so the rectangle's area is A=l*w

#

A=9*12=108

#

Can you now figure out the triangle and then subtract the two.

#

You can look at the image to get the base and height of the triangle.

#

The base is 6 and height is 5

#

Area of triangle is A=0.565=15

#

Thus the total area is rectangle - triangle

#

You should get 93 as the area so see if you can match my answer.

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full flax
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full flax
#

i can't seem to find online if this is true or not. Can i use sum rule of asymptotic notation to add like this?

full flax
#

yes idk where else 😭

left oriole
tribal jetty
#

wtf

frail heron
full flax
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pure sluice
#

how would you solve for x when the denominator and numerator have x in both of them

pure sluice
#

oops ignore the negative sign infront of 2

edgy willow
#

you can just ignore the bottom

pure sluice
#

ohhhhh

#

okok!!!

#

thank you

split chasm
#

can't fully ignore though, still need to ensure that the denominator isn't 0 at the values you found when determining whether a solution is valid.

gusty heart
#

but for this problem you can just keep in mind that you have to make sure the denominator isnt 0

pure sluice
#

so as long as (3x-x^2)^2 doesn't equal 0, it's fine?

gusty heart
#

yes

pure sluice
#

ok tahnk you!!

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quiet turret
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quiet turret
#

how do i solve d

#

my equation is $500=4x^3-80x^2+400x$

solid kilnBOT
quiet turret
#

right?

#

someone please?

#

😭

young swift
#

are you sure that's the equation?

#

the equation should be $x^3-40x^2+400x$

solid kilnBOT
#

InfinityMango

young swift
#

I got there by using (20-x)(20-x)x

quiet turret
#

its (20-2x)

#

not (20-x)

young swift
#

oh im dumb wow

young swift
#

anyway, you should just be able to bring the 125 over to the left

quiet turret
#

$x^3-20x^2+100x-125=0$

#

then?

solid kilnBOT
young swift
#

then you can refactor it

quiet turret
#

wdym by refactor

young swift
#

get it back into the form (x-a)(x-b)(x-c)

#

you can use polynomial division

#

oh wait, it might be easier to use rational roots

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#

@quiet turret Has your question been resolved?

quiet turret
young swift
#

its one way of finding your first factor

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static fern
#

Can you check this?

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vernal warren
#

dont know why teacher wrote "no"

static fern
#

Why did I get 2/10

#

lol

#

He gave me 2/10

vernal warren
#

it is correct tho u didnt do any thing wrong and proved

static fern
#

Exactly

#

Thanks

#

Are you sure it is correct

#

?

wind sonnet
#

you did mess up the signs

static fern
#

Where

#

I removed the minus 1

split chasm
#

think a lot of marks were deducted from the laziness of not having theta

static fern
#

Nope

split chasm
#

i also don't see this question being worth 10 marks

#

where does it say how much its worth

static fern
#

It doesn’t but he said in class

static fern
split chasm
#

did you ask your teacher why you lost marks?

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dusky tinsel
#

how to do ' - would u derive accel twice to get dispalcement, howevre i di that and when t = 0, i got -12 (not 1m to the right as said)

dusky tinsel
#

this question

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#

@dusky tinsel Has your question been resolved?

hallow crane
dusky tinsel
dusky tinsel
#

what i tried is setting say, point h on the x acis and b on y
then find area of rectangele (b * H)
it but divided/4 should = the area under the curve from 0 to h
but i stuck when i get bh = h^4 since i cant... prove that

hallow crane
#

choose 1

dusky tinsel
#

but im just doign the working rn

hallow crane
#

let the length of the rectangle be l and the "width" of the rectangle is f(l)

dusky tinsel
#

i just thought while i try do the acceleratiion one again maybe you can figure out where i went wrong/how to do ^

hallow crane
hallow crane
#

can you get the area as a function of l?

dusky tinsel
#

lw

hallow crane
#

what is w?

dusky tinsel
#

width and length

hallow crane
#

w = f(l)

#

I know

#

I mean w is just f(l)

dusky tinsel
#

ah k

hallow crane
#

so for some l, we have the width is l^3

#

no?

dusky tinsel
#

hm

#

area of rectangle is length * width, so whys w = f(l), since the function doesnt even have a 'l' value so its not rly a function i dont think, confused there

hallow crane
#

area = length * width and you can do nothing about it if you're doing single variable calculus

#

you want area as a function in a single variable

#

Anyway, look at the red point

#

if x = l then the y coordinate is necessarily l^3 lol

dusky tinsel
#

oh didnt know that

#

is that cuz x^3

#

and how that works

#

im sorry i have to go eat dinner right now so wont respond just wanted to let you know

hallow crane
#

I.e. x = 2 would give y = (2)^3 = 8 and this point lies on the curve y = x^3

dusky tinsel
hallow crane
dusky tinsel
#

l^4

#

i think i got it from here hopes

hallow crane
#

now try to integrate the function to get the area under the curve

#

so integrate the function from 0 to l and then yeah you should immediately have your "proof"

dusky tinsel
#

ye nice thx

hallow crane
#

You're supposed to figure out the value of that constant by using the fact that it was "initially at rest"

#

Then you integrate v(t) to get x(t) + some constant again

#

which you can determine with the "1m to the right at the start"

dusky tinsel
#

works for t = 0 to give 1

#

at t = 2 its displacement is 41/6

hallow crane
dusky tinsel
#

hmm

hallow crane
#

You're supposed to make it work for t = 0 by finding the appropriate constant

dusky tinsel
#

oh yea

#

i got the equation

#

i did the c's

dusky tinsel
#

or am i... delusional and wrong again

hallow crane
#

did you have $v(t) = 6t - \frac{2}{t+1} + C_1$

dusky tinsel
#

uhh

solid kilnBOT
hallow crane
dusky tinsel
#

6t - (2(t+1)^3)/3 + c

#

where c was 2/3

dusky tinsel
#

did you... derive the t+1^2 shouldt it add a power

hallow crane
#

no it looks like you're deriving the second term

dusky tinsel
#

oh

#

uh

hallow crane
#

we're integrating

#

do you know u substitution?

dusky tinsel
#

wait, i thought u.. add a power in integration

hallow crane
#

,, \int x^n \text{ dx} = \frac{x^{n+1}}{n+1} + C

dusky tinsel
#

like t --> t^2

#

yep

solid kilnBOT
hallow crane
#

for n != -1

dusky tinsel
#

oh wait its ^-2

#

hence ^-1

#

not 3

hallow crane
#

yeah and (t+1)^-2 should have a -1 after the addition of exponent lol

dusky tinsel
#

k i got 3t^2 - 2ln(t+1) + 2t + 1 = s

hallow crane
hallow crane
dusky tinsel
hallow crane
#

Looks good

dusky tinsel
#

but that gives displacement

#

how would i find the coords of particle b

hallow crane
#

,w integrate 6x - 2/(x+1) + 2

solid kilnBOT
hallow crane
#

,w -1 + 2 x + 3 x^2 - 2 log(1 + x) + c = 1 when x = 0

solid kilnBOT
hallow crane
#

Sure your s(t) is correct

hallow crane
dusky tinsel
#

wierd

hallow crane
#

+1 is correct

dusky tinsel
#

k

hallow crane
#

c = 2 so -1 + 2 = 1

dusky tinsel
#

or do you need cords of the particle - which idk how to get

hallow crane
#

I mean that's where the collision presumably occurs lol

#

well for those particles to collide, they have to be at the same place

#

disregarding the dimensions of the "particle" itself

dusky tinsel
#

yep

dusky tinsel
#

or are you saying no then to that

hallow crane
dusky tinsel
#

ah lol

hallow crane
#

x = 1 when t = 0

dusky tinsel
#

so basicly dont include physics into it knowing what disaplcement actually is

hallow crane
#

No i mean it's not in 2d where you have the variance of y

#

It's just along a line

dusky tinsel
#

hmm

hallow crane
#

your function is x(t) = something

#

there's no y(t)

dusky tinsel
#

hence anwer is just how far away from origin (in a straight line ofc) the particles collide
just when i see colliding particles i imagine a certgain point where they coolide, not a dispalcement from origin

hallow crane
#

Yeah, that's what you'd be dealing with in 1 dimensional physics problems too

#

It's either along a vertical straight line or a horizontal straight line

dusky tinsel
#

k ty

hallow crane
#

Sure np

#

Are you done with your questions?

dusky tinsel
#

yep

#

.close

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quiet wasp
#

hey quick question

trim joltBOT
#

Please don't occupy multiple help channels.

quiet wasp
#

sorry

wraith hinge
#

say?

quiet wasp
#

can anyone do this

radiant quartz
#

@quiet wasp which part(s) are you stuck on

quiet wasp
#

c and d

radiant quartz
#

okay we'll start with (c)

quiet wasp
#

thx

radiant quartz
#

it tells us the range of h is the same as the range of g

#

so you should be able to immediately write down γ and δ

quiet wasp
#

so 0 and sqrt(3/2) ?

radiant quartz
#

because its bijective hence surjective

#

yep

quiet wasp
#

ohhhh thanks so much

#

what about alpha/beta?

radiant quartz
#

you can work out which value of x does h(x)=0

#

and which value of x does h(x)=√(3/2)

quiet wasp
#

-pi/6 +2kpi?

radiant quartz
#

yes but you need only one value

#

because we dont want every interval that maps it, but only one, because its bijective hence injective

quiet wasp
#

ohh right

#

so which should i use

radiant quartz
#

the one that has 0 in it

#

right?

#

it says h(0) = ½

quiet wasp
#

yeah

radiant quartz
#

So the domain of h better contain 0

quiet wasp
#

so alpha = 0?

radiant quartz
#

nuh uh

quiet wasp
#

oh damm

radiant quartz
proven sluice
#

[-π/6,π/2]

radiant quartz
#

Chill aditi im getting there

proven sluice
#

aight

quiet wasp
#

no it doesnt*

#

oh wait it does

#

sin(-pi/6) = -1/2

#

so yes

radiant quartz
#

yep

#

so we have α = -π/6

quiet wasp
#

ohhhh rightt

radiant quartz
#

and by a similar process you can pick β

quiet wasp
#

so it = 3/2 right?

#

sqrt(3/2) *

#

so therefore pi/2?

radiant quartz
#

yeag, h(β) should = rt(3/2)

#

Yep

quiet wasp
#

so beta = pi/2

radiant quartz
#

correct

proven sluice
#

If that's the case then beta diff ryt?

radiant quartz
#

and we r done with (c)

quiet wasp
#

thanks so much appreciiate it fr

radiant quartz
#

on to (d)?

proven sluice
#

root3/2 is for π/3?

radiant quartz
#

Or u get it now

quiet wasp
radiant quartz
#

Note the change in parenthesis

#

and the different functions

proven sluice
#

Oh alrightt mb thanks

radiant quartz
#

theyre just going to be the opposite to h

quiet wasp
#

but how do we know where to restrict the domain to?

radiant quartz
#

the domain for h^-1 will be the codomain of h

#

and we already worked out the codomain of h

quiet wasp
#

[0. sqrt(3/2) is new domain?

radiant quartz
#

correct

#

forgot to close your square bracket but yes

quiet wasp
#

and the new range is [-pi/6, 7pi/6]

radiant quartz
#

Codomain

#

but yes

quiet wasp
#

yeah sorry

#

ok that makes sense, but how would i explain part c

#

mathematically and backed up with reason

#

are u able to write it out and send, if not its fine

radiant quartz
#

we already talked through it

quiet wasp
#

sorry to sound annoying but r we able to clarify c one more time?

radiant quartz
#

just explain what reasoning you used

#

Okay sure

quiet wasp
#

thx

#

cause i get confused with bijective surjective and injective and what it all allows us to do

radiant quartz
#

the range of h is the range of g
so the range of h is [0, rt(3/2)]
h is bijective so it is surjective
h is surjective so its range is its entire codomain
so its codomain is [0, rt(3/2)]

quiet wasp
#

ohhh this makes total sense now

#

how can we now relate this to find alpha, beta, gamma, delta?

radiant quartz
#

each of the intervals that make up g's domain individually map the entire range twice
h is bijective so it is injective
h is injective so each value should only get mapped to once
each value gets mapped to once so h's domain contains only one half of one of the intervals from g's domain
h(0) exists so 0 is inside h's domain
only one of the halves of the intervals from dom(g) contains 0
this interval is [-π/6, 7π/6]
the relevant half of the interval is [-π/6, π/2] because it contains 0
this is the domain of h

#

so now we have α, β, γ, δ

quiet wasp
#

it makes sense but to clarify, what does this mean "ach value gets mapped to once so h's domain contains only one half of one of the intervals from g's domain"

#

like the half of one interval part

radiant quartz
#

okay so if you see how g maps each interval

#

at the lower end of the interval g is at a minimum

#

then g increases towards a maximum

#

and symmetrically decreases back to a minimum at the end of the interval

quiet wasp
#

right yeah

radiant quartz
#

so each value that g maps to, gets mapped twice by each interval

#

once in the lower half and once in the upper half

quiet wasp
#

OHHH

#

so we restrict it so we only map each interval once

radiant quartz
#

yep

quiet wasp
#

so the domain of h = [-pi/6, pi/2] ?

radiant quartz
#

yep

quiet wasp
#

so that means alpha and beta = -pi/6 and pi/2 respectively

#

and, gamma and delta = h(-pi/6) and h(pi/2) respectively?

radiant quartz
#

yep

quiet wasp
#

so does gamma = 1/sqrt(2) and delta = sqrt(3/2)

radiant quartz
#

well gamma = 0 but delta yes

quiet wasp
#

oh how come gamma wrong?

radiant quartz
#

you just evaluated h wrong

#

,calc sqrt( 1/2 + sin(-pi/6) )

solid kilnBOT
#

Result:

7.4505805969238e-9
radiant quartz
#

0

#

(calculator has rounding error

quiet wasp
#

i thought it was sqrt(1/2)

radiant quartz
#

well you can just plug it in and find out its not

quiet wasp
#

oh shit its 0 haahhaha

#

my bad

#

i was plugging in wrong sorryy

radiant quartz
#

i did tell you so

radiant quartz
quiet wasp
#

hahahahah fair enough thanks very much

#

u literally saved me

#

this topic was garbage, now its less garbage

#

alr cya thanks alot appreciate the help!

radiant quartz
#

o7

#

happy to help 👍

quiet wasp
#

bye!

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crimson void
#

least value of n such that 25^n + 16^n leaves a remainder of 1 upon being divided by 121

fathom gull
#

!status

trim joltBOT
#
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5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
crimson void
#

2

#

i tried putting n = 3k+1,3k+2,3k and taking mod 121

#

but couldnt continue from there

#

the reason for taking n = 3k,3k+1,3k+2 was that 5^3 and 16^3 ,both leave remainder 4 upon being divided by 121

#

i thought maybe that could lead somewhere

trim joltBOT
#

@crimson void Has your question been resolved?

crimson void
#

<@&286206848099549185>

#

<@&286206848099549185>

void anchor
#

So you're saying you're going to find it manually?

#

step by step?

trim joltBOT
#

@crimson void Has your question been resolved?

crimson void
#

<@&286206848099549185>

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river yoke
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river yoke
#

Where is 1 represented here?

#

Shouldn't the beginning of the series begin with 1 and k? But the beginning of the sequence they wrong begins with k(k-1).

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#

@river yoke Has your question been resolved?

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proven palm
#

I'd like to know how this is not a counterexample to the inverse function theorem: let f(x) = x^2, let a = 0. Then f' is invertible and continuous everywhere, but f is not invertible in any neighborhood of a.

naive crest
#

you forgot that the derivative being non zero at a is a condition

proven palm
#

huh it doesn't say that in my textbook

#

wait unless being a C'-mapping implies nonvanishing derivative...

trail ingot
#

send pic of statement in book

proven palm
#

being a C' mapping is just continuous differentiability so the condition is not implied from there...

marble wharf
#

f'(a)=0 is not invertible

proven palm
#

so the texbook just has an error then?

marble wharf
#

in your example f'(a)=0

#

which is not invertible

proven palm
#

oh wait

#

but why would that imply non-invertibility? In my example f'(x) = 2x which should be invertible everywhere by the inverse function g(x) = (1/2)x ... ?

#

Or am I totally misunderstanding inverses here...?

#

wait....ohh

#

OHHH

#

i see now catthin4K

#

because f'(x) is the linear transformation, not just a value

#

thanks so much!

#

.close

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languid coyote
#

Hi! Wanted to confirm some intuition regarding linear maps, null-spaces, and matrix representations.

languid coyote
#

From Axler, we know that:

#
  1. Let $\dim \text{null} : T = k < n$. If this is the case, $\exists$ a matrix representation where $k$ of the columns have all $0$, is that correct?
#
  1. For any matrix representation of $T$ however, this is not necessarily true, but with some matrix manipulation, we should be able to get to the matrix representation where $k$ columns have all $0$, is that correct?
#
  1. Could you help demonstrate how to go from the matrix representation using the standard basis, to the matrix representation with a column of $0$s for the following linear map: $Te_1 = e_1 + e_2$, $Te_2 = e_1 + e_2$?
#

Just those three question, in order from top to bottom!

solid kilnBOT
neon dirge
#

@languid coyote is dim null = dim ker?

#

in your notation

languid coyote
#

yes, sorry just using Axler notation

neon dirge
#

kk np

#

yes first is correct

#

bc you can bring it into Rref form via Gauß algorithm

#

for columns and get k zero-columns

#

@languid coyote 2nd is true as well, slightly oddly worded but yes

languid coyote
#

okay, i guess what im failing to connect then is

#

seeing it in action

#

so wanted to see if you could walk through one with me

neon dirge
#

sure

languid coyote
#

using the linear map above I stated

#

where $e_i$ are the standard basis vectors

solid kilnBOT
neon dirge
#

ok so we have the following matrix:

#

now via Gauß-Algorithm, we can subtract rows and columns from each other

#

if we subtract the first column from the second we receive

#

which gives us the form with a 0-column

languid coyote
#

oh wait hmmm

#

i thought gaussian elimination you can only use rows

#

also, in this case, how have the basis vectors changed

#

for both $V$ and $W$

solid kilnBOT
neon dirge
#

which also allows you to perform manipulations both on rows and columns

languid coyote
#

ah i see hmmm i think transpose comes much later in the axler book

neon dirge
#

kk, transposing just means flipping the matrix diagonally

#

so in the above case

languid coyote
#

so im just tryna understand in terms of whatever basic properties have been explained so far

neon dirge
#

before our basis was (e1, e2) right

languid coyote
#

yep

neon dirge
#

for V

#

and now after the column manipulation

#

notice that we subtracted the first from the second

languid coyote
#

mhm

neon dirge
#

so now our basis is (e1, e2-e1)

#

which makes it so convenient to have done it column-wise

#

bc now we can simply subtract/add the basis vectors too

languid coyote
#

ahhh i see

#

and T(e2 - e1) = 0

neon dirge
#

you can perform this manipulation as you like!

languid coyote
#

so that's why that column is 0

neon dirge
#

definitely experiment a little with manipulating a matrix

languid coyote
#

so i guess the basis is (e2-e1, e2)

neon dirge
#

in case you have some visualisation tool

#

that can help as well

languid coyote
neon dirge
#

hm maybe something like Desmos for starting

languid coyote
#

so i wanted to make sure i really understand why everything is true and then connect it to all the computations

#

so i can have a strong intuition

#

okay this was super helpful, apologies if it was too simple of a question haha

#

thank you!

neon dirge
#

nono, the essence of linear algebra and analysis are crucial

#

and some glance over them leading to uncertainties later on

languid coyote
#

for sure...haha

neon dirge
#

there's also a few neat channels such as 3Blue1Brown which elegantly visualise quite a bit

languid coyote
#

oh yeah i've watched some of his linear algebra stuff, pretty helpful

#

i guess while we're at it one more quick question

#

so for any linear transformation, we know that there exists a matrix representation

neon dirge
#

ys

languid coyote
#

in particular, one where we map the basis vectors of V to the basis vectors of W

#

*to some linear combination of basis vectors of W

#

so it is fair to say that

#

if dim ker T and dim range T are k, n-k

#

then there should exist a matrix representation where

#

i have n-k non-zero columns and k zero columns?

languid coyote
#

yes

neon dirge
#

hm 2nd yes, currently thinking about first

languid coyote
#

like let's say the dimension of V is n, dim ker T is k, dim range T is n-k

neon dirge
#

dym the same linear map

#

has two matrix representations

#

one with k zero columns

#

and one with n-k zero-clumns?