#help-13

1 messages · Page 151 of 1

random kelp
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i watched it

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and ive watched it before

dire geode
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So you should know this doesn't matter

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Since x goes to 0, so does sin(x)

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Their ratio goes to 1

random kelp
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because of the squeeze theorem right

dire geode
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Sure that's one way to prove it

random kelp
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but you'd need to take the reciprocal for that

dire geode
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It doesn't matter

random kelp
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why

dire geode
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Reciprocal or not

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1/1 = 1

random kelp
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so regardless of anything, x/sinx or sinx/x will always equal 1?

dire geode
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The limit part is important

random kelp
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i understand the limit

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sinx/x = 1

dire geode
dire geode
random kelp
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when the limit is approaching 0

dire geode
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What you're typing and what you're thinking are different things

random kelp
random kelp
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since they have the same resulting answer of 0

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their ratio goes to 1 when x is approaching -3

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but thats very strange because when you get to 0 they become 0/0

dire geode
random kelp
dire geode
random kelp
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but couldnt that apply to any trig function

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like x/cosx

random kelp
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or x/tanx

dire geode
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cos(0)=?

random kelp
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1

dire geode
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0/1=?

random kelp
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x/tanx?

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it would work

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thanks then bro

cedar kilnBOT
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@random kelp Has your question been resolved?

cedar kilnBOT
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crude scroll
cedar kilnBOT
crude scroll
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I’m not sure if I set this bounds up correctly

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The region is the circle centred at (0,1) and radius 1

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nvm

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the bound should be r=2sin theta

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.close

cedar kilnBOT
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crude lagoon
cedar kilnBOT
zenith igloo
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how do i solve this?

crude lagoon
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oops

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ill take another one

#

.close

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stray vale
cedar kilnBOT
stray vale
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Hi can anyone help me with sinsiodal functions

cedar kilnBOT
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@stray vale Has your question been resolved?

stray vale
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I already have the solved but I have more questions

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can you help me with the domain

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@dull oxide Also if you can tell me what this is

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equation of the sinusoidal axis

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is it the middle line or is it the actual equation

cedar kilnBOT
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@stray vale Has your question been resolved?

high kiln
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so to be clear you're interested in the x values

high kiln
stray vale
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its a guessing game pretty much

high kiln
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if this is the only picture you're given then it does seem a bit ambiguous yeah

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they should have had a finer grid to make it clear

stray vale
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ya so im not sure

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really

high kiln
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I think anyways that the graph is starting halfway between 180 and 90 degrees, which would be what angle

stray vale
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its

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135

high kiln
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right

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I should have said -180 and -90 degrees actually

stray vale
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ya

high kiln
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and then it looks like it's ending halfway between 180 and 270

stray vale
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225

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isnt it

high kiln
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yep

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so we're interested in all the x values between those two, including them

stray vale
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ok

high kiln
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there's two ways of writing that so I'm not sure which you're more familiar with

stray vale
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its all good i wrote them

high kiln
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ok great

stray vale
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now i need to know

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equation of the sinusoidal axis

high kiln
stray vale
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ok now i need to get that

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ill send the graphs

high kiln
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although you can also write the function of the graph itself with what's shown, so I'm not confident that's the right interpretation

stray vale
high kiln
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ah I see they're definitely asking for the equation of the line then

stray vale
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ok

high kiln
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since these are horizontal lines they should be quite straightforward to find

stray vale
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Ill tell you all the information I found for a

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max=2 min=-2

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there is one period that lasts 720 units

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domain is 0,720

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range -2,2

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amplitude is 2

stray vale
high kiln
stray vale
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asin[k(x-c)]+d

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d=max-min

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a=amplitude

high kiln
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we only need the equation of the axis line, not the sinusoid itself

stray vale
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mmm

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oh

high kiln
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yeah it's a little easier

stray vale
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it says equation of the sinusoidal axis

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thats why i though

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we were looking for the equation

high kiln
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given the context, they're asking for a lot of information you can just read off so I don't think it's the function itself (we would at least need the period first for example, but they ask you for it right after)

stray vale
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ok

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This is grade 11

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so i dont think there are any trick questions

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so i think everything is straight forward

high kiln
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yep

high kiln
stray vale
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ok

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how do I get the equation of the line

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we know its on the 0 axis

high kiln
stray vale
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ok

high kiln
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so the explicit form of a line would be
y = mx + c

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should be familiar

stray vale
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ya

high kiln
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m would be the slope, and c would be the y intercept

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can you fill in values for these with what you see on the graph

stray vale
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ok

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y = noslopex + 0

high kiln
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no slope would just be a slope of 0

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that's correct then though

stray vale
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whats next

high kiln
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that's it you're done

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y = 0 is the equation of that axis line

stray vale
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ok

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axis line is 0 also

high kiln
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yep

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since the slope is always 0, you're left with
y = c
in general, so you can just read off the y intercepts

stray vale
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ya

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-1

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  1. Sketch one cycle of a graph of a sinusoidal function that has the following key features, and identify the remaining key features.

a) maximum: 3,

b) period: $1080^\circ, range: -7 \leq y \leq 11$

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Also what is the period

wraith daggerBOT
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deviousglxy

high kiln
high kiln
stray vale
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i think i wrote the period wrong

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for 2a

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i wrote

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there is one period that lasts 720 units

high kiln
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the period is 720 degrees

stray vale
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ok

stray vale
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my equation is

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f(x)=sinx+2

high kiln
stray vale
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wht not the max is 3

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it will fulfil the requirment

high kiln
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oh sorry

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I thought you meant 2a

stray vale
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no lol

high kiln
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yeah brain fart :P

stray vale
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It wont let me make an equation in desmos peacfully

high kiln
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maximum in the range, got it

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I guess they don't tell you enough information for a) tbh

stray vale
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ya

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always a prob

high kiln
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very annoying :/

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I suppose how they're thinking of it is starting with a sin(x) and then transforming it as they specify

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that's the only way I can see that being answerable

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anyways

stray vale
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only way

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thats the problem with online school

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there is always missing information

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making it impossible to be accurate

high kiln
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if what they mean is maximum and leave everything else, then sine normally gives outputs [-1, 1], but we want it to be from [ _, 3].

because it's a sine we can already say what that blank would be

stray vale
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-3?

high kiln
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yeah

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we're assuming a few things there but that's how I understand this question

stray vale
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ya

high kiln
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I'd then also assume we have a period of 360 degrees

stray vale
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Well I already solved a I gotta do b

high kiln
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since sin(x) on its own does

stray vale
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ya

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im assuming were transfroming the parent function

high kiln
stray vale
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it worked in desmos

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somehow

high kiln
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3a)

stray vale
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it made 3 the max

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ya

high kiln
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b) is well defined anyways

stray vale
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ya

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b) period: $1080^\circ, range: -7 \leq y \leq 11$

wraith daggerBOT
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deviousglxy

stray vale
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were gonna need restrictions

high kiln
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here we have all the info we need

stray vale
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we can make x start at 0 and end at 1080

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yep

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ill try to get a formula

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nvm I got no clue how to get it

high kiln
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since they explicitly say what you need to find

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we've been given the period so we should be able to find k

stray vale
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ok

high kiln
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we've been given the range so d should also be quite straightforward

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c doesn't really matter here since we're only interested in sketching one cycle, which could be at any x

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and the only thing left to find then would be a

stray vale
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ok

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a

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will be 9

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and d is 2

high kiln
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yep

stray vale
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now we need k

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which is

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1080=360/k

high kiln
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yeah and solve that for k

stray vale
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yep

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$\frac{1}{3}$

wraith daggerBOT
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deviousglxy

high kiln
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I'd say the easiest way to sketch this would be with the period, but it also helps to be able to find the function to graph it directly

stray vale
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ya

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im gonna use desmos

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A and B

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Right here

high kiln
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yeah looks right

stray vale
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ok thanks a lot for the help

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im gonna go to sleep

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have a goodnight

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.close

cedar kilnBOT
#
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cedar kilnBOT
zenith stag
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,calc 360-255

wraith daggerBOT
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Result:

105
tropic oxide
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are you asking for help on a subtraction problem? @midnight nova

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also stick to one channel

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ah, i see you refuse to communicate.

cedar kilnBOT
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@midnight nova Has your question been resolved?

short blade
#

.close

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cedar kilnBOT
hybrid wren
#

When an object is accelerating in one direction and then begins to deaccelerate the velocity is reversed or is moved in a negative force from its current direction. However, since this train initially has a negative velocity the "velocity would switch to positive" and with that also be moving in the "right" direction.

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is this the correct thinking for this question?

lone ferry
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why would the velocity swithc to positive?

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have you learned velocity time graphs yet?

hybrid wren
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doesnt it reverse with deaccelleration?

hybrid wren
lone ferry
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oh okay

lone ferry
hybrid wren
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its initial was negative

lone ferry
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yes because the direction of the velocity was the same as teh acceleration (we can't actually know because the problem doesnt say if initially the train was moving at constant velocity, which if it were, the acceleration would be 0) but since the train is slowing down

hybrid wren
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wait doesnt it say the train was moving with a negative velocity?

lone ferry
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yes, but it doesnt say constant velocitty

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so we can't really assume if there was acceleration initially or not

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but since its decelerating, tehre's definitely acceleration

hybrid wren
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so its positive right?

lone ferry
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yes

fair geyser
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yes, the acceleration is positive

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what's the direction, and is it positive is the same question

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looks like a catch, i had to check, apparently it's the same thing

hybrid wren
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😦

hybrid wren
fair geyser
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yes because the train is moving to the left, you need to accelerate to the right to slow down

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and they established that right is positive

hybrid wren
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yeah thats kinda what i was thinking

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so that means that my original statement was alright?

fair geyser
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yeah sure

hybrid wren
#

.close

cedar kilnBOT
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fast mirage
#

Positive acceleration.

cedar kilnBOT
#

@fast mirage Has your question been resolved?

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fast mirage
cedar kilnBOT
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crimson sedge
cedar kilnBOT
crimson sedge
#

someone teach me inverse

slate lintel
#

$x = \frac{2y+3}{5y+4}$ solve for y

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hint: start with cross multiplication or in some way clearing the denominator

wraith daggerBOT
#

Hayley

crimson sedge
#

thanks

#

.close

cedar kilnBOT
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jovial ravine
austere hull
#

what's the question asking you?

jovial ravine
#

Im not great describingit, im gonna try
Im trying to make a function that contains L l H h
With
h=y at x=0
H=y at x=L*l

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@austere hull Likely not well worded, do you roughly know what i mean :/?

austere hull
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nope

jovial ravine
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@austere hull How could i explain it better? :o

austere hull
#

if you have the original question

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,tex .original

wraith daggerBOT
austere hull
jovial ravine
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I dont xD its for a mod, not homework.

austere hull
#

wait do you mean like how to put the letters on the desmos or what

tropic oxide
#

well we'd still like to know what problem youre solving

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like be it for a mod or otherwise

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as is youve abstracted away too much of the detail

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so we cant really get a grip on what it is you're doing yknow?

jovial ravine
jovial ravine
tropic oxide
#

ok hold on

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so let me see if i've got this right

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in this game you are modding, your player character (presumably) has a stamina bar.

jovial ravine
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Yes

tropic oxide
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you want to make it so that your character moves at different speeds depending on how high their stamina is.

jovial ravine
#

Yes, the values represent ingame settings i made.

tropic oxide
#

and the way you want to do that is this:
if the stamina is at or above some threshold percentage, the character moves at their max speed.
but if the stamina goes below the threshold, then the character's move speed decreases linearly, down to their min speed at zero stamina.

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is that correct?

jovial ravine
#

Perfectly correct! 🥳

tropic oxide
#

right ok

#

makes perfect sense

#
double getMoveSpeed(double currentStamina, double maxStamina, double stamThresholdPercent, double minSpeed, double maxSpeed) {
  // assume 0 <= stamina <= maxStamina and 0 < stamThresholdPercent < 1
  double staminaThreshold = stamThresholdPercent * maxStamina; // stamina threshold

  if (currentStamina >= staminaThreshold) 
    return maxSpeed; // stamina above threshold => move at max speed

  // go from minSpeed at currentStamina = 0 to maxSpeed at currentStamina == staminaThreshold 
  double stamPctUnderThreshold = currentStamina/staminaThreshold ;
  return minSpeed + (maxSpeed - minSpeed) * stamPctUnderThreshold;
}
#

something like this

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bit wordy but i think this is in compliance with SOME style guides

jovial ravine
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No i already have the code in place. 😅
I was just asking for the function.

tropic oxide
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wait, you weren't trying to code this?

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what is your goal exactly

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are you documenting existing code or

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confused at your goal here lmfao

jovial ravine
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Just a short formula that does this. :o

tropic oxide
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"formula" in what sense?

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what are you gonna use it for?

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desmos fuckery?

jovial ravine
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Yes

tropic oxide
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right ok so you could've said that.

tropic oxide
#

youre gonna need to make a piecewise function here

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with somewhat more descriptive names for things than you wrote

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not ideal but i tried

jovial ravine
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Just the one line would be enough :o
I have it as: if (x <= L*l) then

tropic oxide
#

Just the one line would be enough :o
no, it would not.

tropic oxide
#

you have to explain what all of your variables mean if you want their meanings to be known to more than 1 person

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you have not done that

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i have

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i wrote down the meanings of all the parameters i introduced

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min speed, max speed, stamina cap, stamina threshold %, everything is labeled as expicitly as possible

jovial ravine
#

This (orange) also works, but it includes L*h which is something that i dont want for the green line.

tropic oxide
#

listen

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do you really want to stick with this naming scheme you've got

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or are you not even understanding what i'm getting at by getting all fired up about names

jovial ravine
#

if (stamina <= maxstamina*l) then {speed = (line function)} else {speed = maxspeed}
I just dont know the line function.

tropic oxide
#

if stamina <= maxstamina * thresholdPercent:
speed = minspeed + (maxspeed - minspeed) * stamina/(maxstamina * thresholdPercent)
else speed = maxspeed

#

but this is basically the code

#

which i sent earlier

#

and which you rejected

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then you said you wanted to do this in desmos, so i did it in desmos for you

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but you didn't like that either

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i don't know what you want

jovial ravine
tropic oxide
#

this is what piecewise functions look like in desmos.

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yours is most naturally given in exactly such a form

thin hedge
#

ur smart asf

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@tropic oxide holy

jovial ravine
#

Works 🥳 🎉 !

#

@tropic oxide Thanks a lot! Sry im so bad with words. pensivebread

#

.close

cedar kilnBOT
#
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crimson sedge
#

(Opening again because i dont think i quite understood last time)

How many possible arrangements can you have of a ternary string of length ten where there are at least four 0's in any position, or 00 at the beginning

The following are examples of acceptable strings:
0021211211, 1211000011, 0000000000

tropic oxide
#

count the invalid ones and subtract from 3^10

crimson sedge
#

so we can start with the first, if we assume one of the positions has the 0, we are left with 9 positions of which only 1 or 2 are possible

#

meaning 2^9 arrangements for the first

tropic oxide
#

i think you've missed some...

crimson sedge
#

oh you are right

tropic oxide
#

i think it is better to break it down like this:

#
  • any of 11 12 21 22 followed by one of:
    -- no zeros
    -- one zero
    -- two zeros
    -- three zeros
  • any of 01 10 02 20 followed by one of:
    -- no zeros
    -- one zero
    -- two zeros
crimson sedge
#

OH that's actually much smarter okay

#

hmmm wait do we multiply by 4 if we take, say, 11 for the first category?

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to account for the three other numbers

#

Question, is this process less tedious than using inclusion-exclusion?

crimson sedge
# tropic oxide yes

Okay may I ask for what was wrong with my solution for this using inclusion-exclusion?

I did the following:

We can fix four positions of the 10 positions to have 6 remaining, to account for the at least 4 0's possibility, then we can use the product rule on the remaining 6 to get 3^6

We can do a similar process with the "00 at the beginning" to get 3^8

we can exclude 3^6

which leaves us with 3^8 + 3^6 -3^6 = 3^8

#

im guessing it is the first

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i cannot just "fix" 4 random positions, can i

muted bear
#

How did you get the exclusion part?

tropic oxide
#

this feels slippery

muted bear
#

Very

tropic oxide
#

We can fix four positions of the 10 positions to have 6 remaining, to account for the at least 4 0's possibility, then we can use the product rule on the remaining 6 to get 3^6

that's if you have EXACTLY four zeros.

#

and 2^6 surely not 3^6...

muted bear
#

category A would be ?
category B would be?

tropic oxide
#

this is all slippery as fuck

crimson sedge
#

ah i see i guess thats why

#

fair enough

muted bear
#

You have to be very careful when youre making assumptions in combinatorics

crimson sedge
# muted bear category A would be ? category B would be?

-no zeros:
we have '11' fixed, then 8 remaining positions which leaves us with 2^8 choices
one zero:
same process but we can fix 3 positions instead, 2^7
two zeros:
2^6
three zeros:
2^5
meaning ultimately:
4(2^8+2^7+2^6+2^5)

#

is this right?

#

for the first category

muted bear
#

Ohh at least four zeros

#

Oops

#

One sec

#

Why is 11 fixed though? Cant it be 22 or 12 or 21?

crimson sedge
#

i multiplied by 4 at the end

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to account for the other 3

muted bear
#

Dont forget about the position of the zero as well

#

You have n remaining spaces

#

You have to choose k to be 0s

crimson sedge
#

ugh wait

#

i cant just fix a 0

#

because it can be any of them?

#

okay is 4*2^8 good to go for the no-zero case first of all?

crimson sedge
#

like

#

the order does matter does it not

muted bear
#

For all of them

#

You cannot fix the 0 when you start getting them

crimson sedge
#

okay understandable

crimson sedge
#

i guess it doesn't matter because the 'ordering' of the positions themselves doesn't matter, you are just looking to see which takes what 0

#

okay so it would be $\binom 8 1$ ways

wraith daggerBOT
crimson sedge
#

but how do you connect that..

#

wait is it simply 4*(8 choose 1) for the second case

muted bear
#

No, you also have the other 7 nonzero slots

crimson sedge
#

heh

#

no hmm

#

u would be multiplying it wouldnt you

muted bear
#

Yup

crimson sedge
#

i cant wrap my head around this totally

#

oh wait

#

its clicking

#

okay

#

okay

#

okay

#

hmmmmmmmmmmmmmmmmm

#

i seeeeeee

muted bear
#

So based on the way youre doing this, your two groups are mutually exclusive and dont need pie

crimson sedge
#

yeah

#

so all in all

#

the solution is this

muted bear
#

I actually think this might be kind of aime level bashing, but the pie solution is not much better

crimson sedge
#

[
3^{10} -\bracks{\vp{\int}4\parens{2^8 +2^7\binom 8 1 +2^6 \binom 8 2 + 2^5 \binom 8 3} + 4\parens{2^8 +2^7\binom 8 1 + 2^6 \binom 8 2}}
]

wraith daggerBOT
muted bear
#

aime combi questions are notorious for being really bashy and prone to mistakes

crimson sedge
#

thats understandabble

crimson sedge
muted bear
#

Yeah i think it looks fine

crimson sedge
#

oh but like

#

[
\sum_{j=0}^n a^{n-j}\binom n j
]

wraith daggerBOT
crimson sedge
#

this is what happened in the problem

#

so like, it was binomial theorem

muted bear
#

Not really

#

Very xlose though

crimson sedge
#

oh yeah i guess there should be an extra factor in there

#

hmmmmmmmmmmmmm

#

fair enough

#

btw garlic, just for my own understanding, but if you were to explain the binomial theorem in an intuitive way, how would you put it?

muted bear
#

Iirc theres some weird gen func thing you can do, but im not experienced enough with gen funcs to remember

crimson sedge
#

i heard a lot of explanations but i am curious to heaar more thonk

muted bear
#

The swinging pendulums

#

I really shouldve made the some video 😔

#

Brb

untold torrent
crimson sedge
#

yeah

untold torrent
#

what does it evaluate to?

crimson sedge
#

no idea

#

lets see

untold torrent
#

well ig ill write it

crimson sedge
#

oh okay thank you xd

crimson sedge
#

wait is there a video on it actually

untold torrent
#

,w 3^10 - (4 * (2^8 + 2^7 * 8 + 2^6 * (8 choose 2) + 2^5 * (8 choose 3)) + 4 * (2^8 + 2^7 * 8 + 2^6 * (8 choose 2)))

wraith daggerBOT
untold torrent
#

damn, not what I got

#

,w 27305 * 2

wraith daggerBOT
untold torrent
#

hm

#

the digits are 0, 1, 2 right

#

oh i see my mistake

#

fuck now i undercount

muted bear
untold torrent
#

@muted bear so i've tried solving this for fun and I'm getting a different answer

#

would it be fine if you help me figure out where it's wrong

#

oh

#

i see what i did wrong

#

nevermind

#

just when I'm about to type it

muted bear
#

Oh aight

untold torrent
#

@crimson sedge for the binomial theorem, just try to write all of the parenthesis (a + b) multiplied next to each other

#

then, the question is, what coefficient do you get in front of the a^k term for example

#

to get a^k, you need to multiply exactly k a's together, and you have (n choose k) ways of choosing the parenthesis from which the a's will come from

#

each one of those possibilities contributes a coefficient of 1

#

then, the rest of the parenthesis (n-k of them) will have to contribute b's instead

untold torrent
#

so u also get b^(n-k)

#

so in general its a^k * b^(n-k) * (n choose k)

#

and you do this for every possible power of a

crimson sedge
#

okay so like

#

for example

#

(a+b)^4 for now

#

let's say we want to know the coefficient of a^4

#

since we are multiplying all 4 a's together, then it is 4 choose 5

untold torrent
#

well there's only one way to get a^4, which is to choose a from each of the parenthesis

crimson sedge
#

4*

untold torrent
#

so its 1

muted bear
#

you have all ↙️

untold torrent
#

no

untold torrent
muted bear
#

Swining pendulum analogy

crimson sedge
#

so i guess 4 choose 3

untold torrent
#

yes, but u also get some b's

#

u can't just ignore the one parenthesis leftover

#

if you don't to take an a from it, you have to take b

#

so (4 choose 3) * b is the coefficient of a^3

untold torrent
#

its like FOIL

#

each combination of stuff in the parenthesis gives you a term in the sum

#

and we're asking how many ways are there to get a term of a^3

#

you'd have to choose 3 a, and 1 b

#

and there are (4 choose 3) ways of doing that

crimson sedge
#

0 b no?

untold torrent
#

4 parenthesis

#

3 a

#

so 1 b

crimson sedge
#

oh i see

untold torrent
#

anytime you multiply, you'll get that the number of a's and b's add up to n

#

thats important to understand

#

because u must multiply something from each parenthesis

#

so the total number of a's and b's that you multiply are n

muted bear
#

Lex ill make the binom video for you at some point

untold torrent
#

binom video?

#

wdym

crimson sedge
untold torrent
#

hmm

crimson sedge
#

i guess i get the n choose k part of binom theorem

untold torrent
#

like

crimson sedge
#

but not the a^n b^n-k part

crimson sedge
untold torrent
#

imagine you have
(a+b)(a+b)(a+b)(a+b)

#

and you only choose the 3 first a's

#

when you multiply those 3 a's, you're gonna get a term of a^3 in the first three parenthesis

#

(a^3 + ...)(a+b)

#

but u still have one more parenthesis leftover

#

its still being multiplied

#

so the a^3 is not yet a term in the final sum

crimson sedge
#

yeah fair enough

#

ymm

#

hmm

#

so like

untold torrent
#

think of it as expanding the first 2 parenthesis, and then multiplying that by another parenthesis, and so on

#

each time u do that u must be adding an a or b to each term

#

ok i gtg

crimson sedge
#

no worries

crimson sedge
#

oh wait

#

so its like

#

for every multiplication you have to make a choice of which other paranthesis you are using?

#

okay wait

#

this actually kinda is making me understand

#

i will think more

#

thank you

#

.close

cedar kilnBOT
#
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cedar kilnBOT
#
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fiery whale
#

$\text{Show that if a and b are real numbers and } a \neq 0 \text{, then there is a unique number r such that } ar + b = 0$

wraith daggerBOT
#

monkagoras

fiery whale
#

I have tried to transform this into a logical proposition

#

I got the following:

#

$\forall a \forall b (a \neq 0 \land \exists r (r \neq a \implies ar + b = 0)$

wraith daggerBOT
#

monkagoras

fiery whale
#

However when I tried to prove by using this expression as base I got something very weird

#

Is the expression I did equivalent to the original statement?

crimson delta
#

no

#

nothing in the original statement says that r is not a

fiery whale
crimson delta
#

thats a different statement

fiery whale
fiery whale
crimson delta
#

one thing you could write is $\forall a \forall b (a\neq 0 \implies \exists ! r: ar+b=0)$

wraith daggerBOT
#

denascite

fiery whale
crimson delta
#

yeah it doesnt

#

not sure why you want to translate it into a logical expression in the first place

#

just solve the equation for r

crimson delta
#

if you can solve for r then r has to be unique

lunar lynx
fiery whale
#

Proving by case is not that good for practice

fiery whale
#

however I cannot find a way to express that uniqueness correctly :despair:

crimson delta
#

nothing about this needs contradiction

#

you just need $ar_1 + b = a r_2 + b \implies r_1=r_2$

wraith daggerBOT
#

denascite

fiery whale
lunar lynx
#

That's contradiction. Lol. That's what i was talking about.
You assume first that let's say there are two namely r1 and r2 and then you show that they have to be equal.

lunar lynx
crimson delta
#

thats not what contradiction is

fiery whale
crimson delta
#

there is no contradiction in sight

crimson delta
#

for contradiction you would first have to assume that r_1 and r_2 are different, then arrive at r_1=r_2 and there you have your contradiction

#

which is completely unnecessary

lunar lynx
lunar lynx
crimson delta
#

I didnt make the assumption that they have to be different

#

I am just saying that r_1 and r_2 are both numbers satisfying this property. and then showing that they are equal

#

I am not assuming that I have two distinct numbers r_1 and r_2 satisfying this property

lunar lynx
#

Then you didn't prove anything.
You said that x = y
and ax +b = ay +b
Thus, x is unique. That doesn't make any sense.

crimson delta
#

I didnt say r_1=r_2 at the beginning

#

let r_1, r_2 be some numbers satisfying ar_1+b=ar_2+b

#

then r_1=r_2

lunar lynx
crimson delta
#

no I am not saying they are different

#

I am not saying anything about the relationship of the two at the beginning of the proof

#

only at the end I conclude that they are equal

lunar lynx
crimson delta
#

I didnt say at the beginning of the proof that they are not different

#

I didnt say anything about them at the beginning of the proof

#

leaving the possibility open for both to be the case

#

but then due to the proof I found out that the only possible case is that they are equal

fiery whale
#

thank you for the help, im closing this

#

.close

cedar kilnBOT
#
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feral juniper
#

I am given these 4 vectors and I am supposed to find the Coordinates of v in the Basis B=(b_1,b_2,b_3) I already know that B is a basis of R^3 some help would be appreciated

feral juniper
#

do I just put b_1,b_2,b_3 in a matrix B and calculate Bv?

crimson delta
#

you want to solve a1b1+a2b2+a3b3=v

#

thats just a linear system of equations

feral juniper
#

so I can write it a matrix and do the gaussian alogrithm?

crimson delta
#

yes

spice kraken
#

you can also do B^-1 * v

crimson delta
#

for that you would have to calculate B^-1. which is harder than solving the system

feral juniper
#

why does that work, let v be the given vector and w be the vector that represents v in Basis b

feral juniper
crimson delta
#

if w are the coordinates then Bw=v

#

w=(a1, a2, a3) with the notation from earlier

#

so w = B^-1 v

feral juniper
#

thanks

#

this helped

#

a lot

#

.close

cedar kilnBOT
#
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hazy flicker
#

Hello! Could somebody maybe help walk me through this?.. I have a couple questions

hazy flicker
#

so like, if BOTH the bounds are infinite, how do you set it up?

crimson sedge
#

[
\int_{-\infty}^\infty \map f x \dd x = \int_{-\infty}^a \map f x \dd x + \int_{a}^\infty \map f x \dd x
]

wraith daggerBOT
crimson sedge
cedar kilnBOT
#

@hazy flicker Has your question been resolved?

indigo magnet
#

@hazy flicker close this Channel if you finished

hazy flicker
#

@crimson sedge @indigo magnet okay so what about this example :

#

like since one of them are zero how does it work instead

#

I think it is continious on the bound?..

#

so I guess it's like a normal one hold up

indigo magnet
#

Wait

#

I tried it's not verified

cedar kilnBOT
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feral juniper
#

Let U be a linear Subspace of R^n how do I find a Matrix A over R such that

U = Ker(A)

feral juniper
#

Also U is given by the span of 2 vectors

tropic oxide
#

what's n

feral juniper
#

but I dont know the idea so thats why I ask for the general case case

#

n=4

tropic oxide
#

hm

#

i mean ok like

#

you could find as many vectors orthogonal to U as it would take to extend a basis of U to one of R^n

#

and then just package these orthogonal vectors as rows into a matrix

feral juniper
#

so let u_1 , u_2 be the span of U
then I want to find

#

?

#

this a matrix is A, when v1 and v2 are orthogonal

feral juniper
tropic oxide
#

yeah but your u_i don't go in it

feral juniper
#

so I have a 2x4 matrix=

#

?*

#

why would that work?

feral juniper
#

so I cant use that

tropic oxide
#

why not

#

also I am not given a Inner product space
so I cant use that
can you show exactly what you ARE given then

feral juniper
#

Let U be a subspace of R^4 find a matrix A over R such that U = Ker A

tropic oxide
#

i don't see anything that explicitly forbids referring to dot products in some capacity.

feral juniper
#

we had not defined the inner product at that point

tropic oxide
#

ok so then you could have said "we don't have access to inner products at all"

#

ugh this is gonna be annoying as all hell to write out

feral juniper
#

as far as I remember this was just an annoying calculation

crimson delta
#

I mean you dont have to use the words dot product and orthogonal

#

but the calculation is the same anyway, no?

feral juniper
#

actually yeah ig

cedar kilnBOT
#

@feral juniper Has your question been resolved?

cedar kilnBOT
#
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topaz sleet
cedar kilnBOT
topaz sleet
#

I dont understand how to calculate the length of the shadow

cedar kilnBOT
#

@topaz sleet Has your question been resolved?

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halcyon adder
#

What does divergent mean

cedar kilnBOT
long arrow
#

area under the curve cotgx on the interval 0 <= x <= pi/2 isn't finite

#

aka improper integral does not converge

halcyon adder
#

Because power -inf is 0, no?

long arrow
#

because result of the integral isn't finite (result of the limit is inf)

#

you can imagine cot(x) graph

#

x = 0 is an asymptote

#

if x tends to 0 from the right side we have that cot(x) tends to +inf

halcyon adder
#

Gottcha

#

Read that wrong

#

So you mean to say that if an integral is not finite it is divergent

cedar kilnBOT
#

@halcyon adder Has your question been resolved?

#
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slim crown
#

I got the integral given at the bottom and when evaluating it I got 9/2, and im not sure why its incorrect

slim crown
#

I got 1/3(-2x/3 + 2)^3 + x^2(-2x/3 + 2) then integrated again with respect to x

dawn junco
#

,w integrate 1/3(-2x/3 + 2)^3 + x^2(-2x/3 + 2) between 0 and 3

wraith daggerBOT
dawn junco
#

seems like you goofed up your last integral

#

@slim crown

slim crown
#

ew ok thanks

#

.close

cedar kilnBOT
#
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serene bison
#

how do i get this wrong?

cedar kilnBOT
serene bison
#

I found the height of the triangle, i know that using pythagorean theorem, 4^2+x^2=10^2

#

height = 9.16515138991

#

(1/2) 32*9.16515138991

#

and then add the base which is 8^2

#

which i get 210.64~

cerulean star
#

Finish this

#

top figure is the top-down view projected against the ground plane.

#

bottom figure is a right triangle which stands up from the ground plane. y is the height.

#

oh

#

but I don't think you need the height y here

#

let y be the height of the triangle face, not the pyramid

#

then

#

4^2 + y^2 = 100, as you said

serene bison
#

i re did it and it said my answer was correct

#

i just did the same thing but didnt add the base

cerulean star
#

cool

serene bison
#

because it talks about the top of the pyrmid

cerulean star
#

good job

serene bison
#

.close

cedar kilnBOT
#
Channel closed

Closed by @serene bison

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serene bison
#

.reopen

cedar kilnBOT
#

cerulean star
#

?

#

is there more?

serene bison
#

well

#

i wanna calculate it first and see if its right

#

but i dont want to this to close

#

(its a different problem)

#

204.1?

#

i found the slant height which was 13

#

5^2+12^2=13^2

cerulean star
#

ok

#

$A = \pi r(r+l)$

wraith daggerBOT
#

.disorganized

serene bison
#

it talks about the top cone shaped

#

right

cerulean star
#

so what's the problem?

serene bison
#

i use pi R l

serene bison
cerulean star
#

formula on google is

#

$A=\pi r\left(r + \sqrt{h^2 + r^2}\right)$

serene bison
#

is that surface area

#

or

wraith daggerBOT
#

.disorganized

cerulean star
#

surface area

#

oh...

#

they are including the base.

#

get rid of interior r

#

then like you said

#

it's pi*r*l

serene bison
#

yeah

#

thats just how i learned it

violet night
serene bison
#

umm

cerulean star
serene bison
#

i guess im done here

#

.close

cedar kilnBOT
#
Channel closed

Closed by @serene bison

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cerulean star
#

it's a reference in exactly one movie

#

to something nobody understands

cerulean star
cedar kilnBOT
#
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rancid surge
#

this is my work below;
n(s)=(10C1)(9C8)(2C1)
n(e)=(9C1).1.1.1
P=n(e)/n(s)=1/20

rancid surge
#

but this is wrong

#

hello some one help to solve this

cedar kilnBOT
#

@rancid surge Has your question been resolved?

rancid surge
#

.close

cedar kilnBOT
#
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rancid surge
#

this is my work below;
n(s)=(10C1)(9C8)(2C1)
n(e)=(9C1).1.1.1
P=n(e)/n(s)=1/20

#

.close

cedar kilnBOT
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uncut steeple
cedar kilnBOT
uncut steeple
#

Does anyone know how I can solve this question?

nova geyser
uncut steeple
#

How

#

I have no idea what that is btw

uncut steeple
frail fern
#

can someone please help me to find the area of the shaded portion using integration?

woven flare
# uncut steeple ???

The power of a point theoreom has three parts, but the one that's relevant right now states that:
TS x RS = VS x WS

uncut steeple
#

Oh ok thanks

uncut steeple
#

VS and WS are equal right?

woven flare
#

yeah, should be

nova geyser
uncut steeple
#

I got 6 can you check is it right

uncut steeple
uncut steeple
woven flare
#

yes

uncut steeple
#

Ok thanks

#

May I ask another question?

woven flare
#

sure

uncut steeple
#

How would we go about this question?

woven flare
#

well

uncut steeple
#

I have no idea about this one

nova geyser
uncut steeple
#

I think ik what you mean but how do I get the full radius from that

woven flare
#

draw a diagram

uncut steeple
#

I did

woven flare
#

ok

nova geyser
uncut steeple
nova geyser
#

picture it

uncut steeple
#

That’s meant to be the hypotenuse 16.97

#

And the chord is divided in half 12

nova geyser
uncut steeple
#

+2?

nova geyser
uncut steeple
#

Why plus 2

nova geyser
#

$a\sqrt{b}$

wraith daggerBOT
#

.ivmcs

nova geyser
uncut steeple
#

Shouldn’t it be 12^2+12^2

nova geyser
uncut steeple
#

,w \sqrt{12^2*12^2}

uncut steeple
#

Oh shoot yea

nova geyser
uncut steeple
#

Ohhh

nova geyser
#

,w \sqrt{12^2+12^2}

uncut steeple
#

Ok where do I go from here

nova geyser
#

$12\sqrt{2}$

wraith daggerBOT
#

.ivmcs

uncut steeple
#

Oh wait that is the radius

woven flare
#

yes

uncut steeple
#

Damn

nova geyser
#

you see your picture

uncut steeple
#

Ye

#

This is 110 right

#

Or 250?

#

Please let me k ow which one of either cause it’s one of them

nova geyser
uncut steeple
#

360

nova geyser
#

wait

uncut steeple
#

Yea

nova geyser
#

RTS=360-70

uncut steeple
#

290

nova geyser
#

290

#

i think like that

uncut steeple
#

You are crazy….

#

Can you stay on here cause I might have a few more small questions like these I need help in

nova geyser
#

cuz i have dif usage of that in myyy country

uncut steeple
#

Thanks

uncut steeple
#

I’ve drawn this

nova geyser
uncut steeple
#

So where do I go from here

#

Is x=18

#

No

nova geyser
nova geyser
uncut steeple
#

That symbol like over as means arc

#

Ab*

#

No idea?

nova geyser
#

nvm i know

uncut steeple
#

Oh ok how?

uncut steeple
nova geyser
#

nvm

#

i am not sure lol

uncut steeple
#

Is this 68?

uncut steeple
uncut steeple
#

You not sure about this one whether @nova geyser ?

nova geyser
#

cuz i studied math olympiad not school math question sorry

uncut steeple
#

Ok all good

#

This?

#

This one I’m not sure about at all

#

Yes, no?

#

<@&286206848099549185>

lone ferry
#

try drawing diagram

lone ferry
#

thats right

uncut steeple
#

Thank you your always saving me

uncut steeple
uncut steeple
uncut steeple
lone ferry
uncut steeple
#

Ok, but can you explain the question is just replied to?

lone ferry
uncut steeple
#

It’s confusing me

uncut steeple
#

Corresponds idk

lone ferry
uncut steeple
#

Ok

#

Is it ac

lone ferry
#

yes

uncut steeple
#

So 2x+15=5x

lone ferry
#

(5x)/2

uncut steeple
#

Oh cause it’s an inscribed angle?

lone ferry
#

yes

uncut steeple
#

Ok answer is 75 thanks so much

lone ferry
#

ofc

uncut steeple
#

Ok I. Drew it

#

How do I find radius though I don’t know EF

#

???

lone ferry
#

u drew the diagram wrong

uncut steeple
#

I did?

lone ferry
#

line EF is tangent to the circle at point E

uncut steeple
#

So this?

lone ferry
#

yes

uncut steeple
#

It’s a special triangle ok

#

Lemme solve this

lone ferry
#

✅✅✅

uncut steeple
#

Is this an inscribed or center angle

#

I think it’s inscribed right v

lone ferry
#

which one?

#

which angle

uncut steeple
#

Wait mb that was bad question

#

Like sr would be half of 105?

#

Or not is the answer 150?

#

Mb for so many question I only have two short ones after this

uncut steeple
#

@lone ferry ????

#

Or it’s 255 🤦‍♂️

#

Idk

lone ferry
#

send ur work

uncut steeple
#

I have no work

lone ferry
#

okay

#

so do you know that

#

the measure of an arc

#

is equal to the degree of its central angle