#help-26

1 messages · Page 225 of 1

smoky pivot
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Thats... getting concerning...

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Ok its back I just had to restart the laptop again

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So if domain was all reall numbers then... I believe the range is?...

acoustic pecan
#

hm?

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of f or |f|

smoky pivot
#

And that was just the function it's self....

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Now I need to search for y=|f(x)|

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Domain

acoustic pecan
#

does the absolute value have a restriction on its inputs?

smoky pivot
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The outcome can never be negative

acoustic pecan
#

sure, but i asked about the income

smoky pivot
#

Can you define what an income is?

acoustic pecan
#

the input

if i have y=|x|, whats the domain of that

smoky pivot
#

|x|= x

acoustic pecan
#

lost me a bit there

smoky pivot
#

I think I am just as lost

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So this is what I have

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I originally thought I needed to take the given domains and lay them out

acoustic pecan
#

i can tell you that the absolute value has no effect on the input functions domain

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because it takes all of R

smoky pivot
#

So (-si,si)?

acoustic pecan
#

but from the graph we can also see that

acoustic pecan
smoky pivot
#

The range though...

acoustic pecan
#

of f or |f|

#

i think you overthink these things a little

smoky pivot
#

I can not tell what number it is

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Unless thats just 0

acoustic pecan
#

it is indeed, we know that because f crosses the axis

smoky pivot
#

So the range would be [0,si)?

acoustic pecan
#

that is so

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(just to confirm you are using si to mean $\infty$)

thorny flameBOT
#

AℤØ

smoky pivot
#

I cant tell if you were in the Navy or you enjoy talking like a sailor

acoustic pecan
#

just spent a fair amount of time in scotland catgiggle

smoky pivot
#

Nice👍

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Study abroad?

acoustic pecan
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yes and no

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its both a different country, and the same country

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im from england

smoky pivot
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Oh I understand- you are from the UK nice

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Ok so I figured out the absolute value of the last one but the domain for this absolute value is... tricky

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I could use the given pointz

acoustic pecan
#

what are your thoughts

smoky pivot
#

Well, the function is f(x)=sqr root x

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But the line starts from -3

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But the absolute value cant be negative

acoustic pecan
#

it still isnt negative

smoky pivot
#

So... would it fold over the y axis?

acoustic pecan
#

are there any negative y values on that graph?

smoky pivot
#

Making it domain for y=f|x| is [3,si)?

acoustic pecan
#

nope

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youre confusing the input and output

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the absolute value can take negative inputs

smoky pivot
#

So then would it be [-3,si)?

acoustic pecan
#

it would indeed

ruby wedge
smoky pivot
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How do I not mix up the two? Know any simple or specific methods?

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That might be asking too much belay that...

ruby wedge
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think of it as the distance from 0 of x

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well in this case f(x)

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what goes inside of the absolute value is the input right?

smoky pivot
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Yes

ruby wedge
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what comes out is the distance from zero of that input

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-3 is 3 away from 0 on the number line and so is 3 so |-3| and |3| are both 3

smoky pivot
#

Yes

ruby wedge
#

thats it idk if that helps

smoky pivot
#

It does

ruby wedge
#

great

smoky pivot
#

The input is usually (x +/- a) the output is -/+ b

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From what I understand in your phrasing

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So in this case the range sqr root function of |f(x)|= [0,si) ?

ruby wedge
#

it shoud be the same

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as the original function

smoky pivot
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I see

ruby wedge
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because \sqrt{x} never has negative outputs

smoky pivot
#

Aw...

ruby wedge
smoky pivot
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Yes I was

ruby wedge
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oh ok then it is a bit different

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so the absolute value is the same for both functions but the domain is different

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that function is \sqrt{x+3)

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a sqrt can not have a negative inside therefore the domain should not include any x that make x+3<0

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what do you think the domain is then?

smoky pivot
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It would be [3,si)

ruby wedge
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close but no

smoky pivot
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Oh

ruby wedge
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x+3 can be 0

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but not lower

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what x satisfies that condition

smoky pivot
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Hmmm

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I do not know... -3?...

ruby wedge
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yes

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so [-3,si)

smoky pivot
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Ohhhh

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Because its a input it stays negative?

ruby wedge
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yes

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|f(x)|=|sqrt{x+3}| not |x|

smoky pivot
#

Ok I understand that one now

ruby wedge
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good

smoky pivot
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But...how do I find the correct range for this one?

ruby wedge
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well first what do we know about absolute value?

smoky pivot
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It cant end negative

ruby wedge
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correct whatever goes inside must leave as its positive version

smoky pivot
#

And the range is an output?

ruby wedge
#

in this case f(x) is our input for our absolute value

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f(x) has a negative value within its range correct?

smoky pivot
#

Correct

ruby wedge
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so since f(x) is having the absolute value taken of it, the minimum value of |f(x)| range must be the absolute value of the minimum value of f(x).

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which is?

smoky pivot
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Can we back track a little?...

ruby wedge
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ok

smoky pivot
#

Is this something to visualize on a graph?

ruby wedge
#

its not necessary

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if you want you can

smoky pivot
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How would that look?

ruby wedge
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see f(x) has a range of [-1,inf) , f(x) is the input for the absolute value so the range of |f(x)| has to be the absolute value of the range of f(x)

ruby wedge
smoky pivot
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Soooo [1,si)?

ruby wedge
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yes

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good

smoky pivot
#

Wait- the system says its wrong???

ruby wedge
#

?

smoky pivot
ruby wedge
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hmm it seems to be because since the absolute value make -1 to 1 but also supports 0

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that is why

smoky pivot
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Is this another possible error or is-

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Oh you are explaining

ruby wedge
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no yes they are right

smoky pivot
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Alright

ruby wedge
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[0,si)

smoky pivot
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So say if there was a range of [-5,si) its absolute value would turn to [0,si)?

ruby wedge
#

yes

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because the negative values would be mapped as positive and then 0 would be the lowest value for |f(x)|

smoky pivot
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Ah...

ruby wedge
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that was my bad, sorry

smoky pivot
#

Its ok

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We all make errors no matter skill level

ruby wedge
smoky pivot
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Ok so dont mind my white board out but

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So this one...

ruby wedge
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ok so first find the minimum value for (x+1)^2-3

bronze creek
ruby wedge
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it would be easier to do analytically

smoky pivot
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Oh- right-

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I cant rely on a graphing calculator (not allowed for test) so I want to make sure I understand this

ruby wedge
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ok good have you found the minimum value

bronze creek
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if u know the vertex then u can find the domain and range

ruby wedge
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correct

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the range should be the y coordinate of the vertex to infinity and domain is -infty to infty

smoky pivot
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So for my sake- this is is the correct visual right?

ruby wedge
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this is for (x+1)^2-3

smoky pivot
#

So the domain is (-si,si)?

ruby wedge
#

yes

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for both

smoky pivot
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Ok and the range...

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[-3,si)?

ruby wedge
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for which one?

smoky pivot
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The function

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Not the absolute value

ruby wedge
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then perfect

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yes

smoky pivot
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The absolute range... eh...

ruby wedge
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what do you think so far

smoky pivot
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Does the vertex do this?

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The blue is the absolute value

ruby wedge
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its over exageratted but yes

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insted of -3 it is 3

smoky pivot
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So [3,si)

ruby wedge
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no

smoky pivot
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Oh.

ruby wedge
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range is the minimum value of the function to the maximum

smoky pivot
#

Its unending

ruby wedge
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so since absolute value only allows the y value to be a minimum of 0

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then the minimum is?

smoky pivot
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0?

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So... [0,3]?

ruby wedge
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yes so the range is [0,si)

smoky pivot
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Ohhhhh

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I might be overthinking this one

ruby wedge
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your graph is correct

smoky pivot
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The domain is.... [-6,7]?

ruby wedge
#

yes

smoky pivot
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The range is... [-6,7]?

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Wait-

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Nope- yeah

ruby wedge
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for f(x) yes

ruby wedge
# smoky pivot

but for your coordinate at the bottom (-6,1) its wrong it should be (1,-6)

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apart from that so far so good

smoky pivot
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Yes I did fix it after I noticed

ruby wedge
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good

smoky pivot
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Lets seee the domain stays the same

smoky pivot
#

The absolute range is...

ruby wedge
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....

smoky pivot
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[0,7]?

smoky pivot
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XD

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Yeaaaa

ruby wedge
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good job

smoky pivot
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On to the next one⚔

smoky pivot
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Alright!

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Oh thats a bad one

ruby wedge
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much better

smoky pivot
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Indeed

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So the domain of the original function is [-4,0]

ruby wedge
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yes

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graph is good too btw

smoky pivot
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Thanks

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The range is [-4,1]

ruby wedge
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yuppp

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your getting much better

smoky pivot
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Yeaaaaahhhh

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I am understanding- I dont know how long this will last again

ruby wedge
#

keep practicing every once in a while

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eventually it will become second nature

smoky pivot
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Do you know good plaves to practice (that do not cost money)?

ruby wedge
#

Khan acadamy is good

smoky pivot
#

True

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Its good my old school account still exists

ruby wedge
#

yeah you can do that

smoky pivot
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Even though the email is long gone

ruby wedge
#

well you can always make an account

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if you don't have any further questions or think you are ok close this channel

smoky pivot
#

I still do

ruby wedge
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alright bet

smoky pivot
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Quite a few...

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Ok annnd I messed up the range

smoky pivot
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Ohhhhh

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So its always low to high?

ruby wedge
#

yes

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min to max

smoky pivot
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Annnnnddd back to zero understanding.

ruby wedge
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gulp

smoky pivot
ruby wedge
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ok whats up

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i dont understand the phrasing honestly

ruby wedge
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lol

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lets see

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we have the points y_1 and y_2

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we want them to be equal

smoky pivot
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Larger graph

ruby wedge
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thanks

smoky pivot
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No prob

ruby wedge
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oh ok very simple

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we have the two functions y_1 and y_2

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and we want them to be equal what numbers would do that

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aka where both functions intersect

smoky pivot
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Hmm

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So......

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How do I write this

ruby wedge
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what x value(s) makes them equal

smoky pivot
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Ehhh...

ruby wedge
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they intersect eachother at 2 points so there are 2 answers

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what two numbers?

smoky pivot
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6 and

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0?

ruby wedge
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no, those are y values

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we need x values that make the y values equal

smoky pivot
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Dont tell me... do we have to find slope?...

ruby wedge
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no no

smoky pivot
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Phew

ruby wedge
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yeah

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anyway

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so we know that both functions equal 6

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what numbers make that true

smoky pivot
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-1 and 2?....

smoky pivot
#

Wait really???

ruby wedge
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yup

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do you know why?

smoky pivot
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Yesnt

ruby wedge
#

? what

smoky pivot
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The points are a ray they arent intersecting

ruby wedge
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the blue and red functions intersect and x=-1 and x=2 making them equal

smoky pivot
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Ohhhhhhhhh

ruby wedge
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see how in the coordinates shown they have the same y

smoky pivot
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I was focused on y2

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Uhhhh so this was wrong apparently

ruby wedge
#

those are just the names of the functions y_1 and y_2

ruby wedge
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there were various

smoky pivot
ruby wedge
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yeah thats wrong

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its {-1,2}

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because its a set of solutions not coordinates

smoky pivot
#

????

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So the { } is used for

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Solution set

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?

ruby wedge
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yup

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well sets in general

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but yeah

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(-1,2) would imply the point (-1,2) or a range/domain which neither are solutions

smoky pivot
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So what would be solution be?

ruby wedge
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{-1,2}

smoky pivot
#

This one....eh...

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Im lost again

ruby wedge
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show the graph again

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pls

smoky pivot
ruby wedge
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thanks

smoky pivot
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No problem

ruby wedge
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ok so find the domain where the blue function is less then the red one

smoky pivot
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How would I write this?

ruby wedge
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interval notation

smoky pivot
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Soooo (-1,2)?

ruby wedge
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yes

smoky pivot
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So the other stuff is just there to throw it off?

ruby wedge
#

yup

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there is one question left

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after this one ofc

smoky pivot
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Yes

ruby wedge
smoky pivot
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Eh... y1 > y2 is

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Eh...

smoky pivot
#

I wanna say... D?...

smoky pivot
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I dont fully understand that one but it just occured to me Im at question 12... out of 27...

ruby wedge
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its important to understand

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so

smoky pivot
#

Of 2.4... I havent gotten to 2.6 or the review (approximately 30 questions each)... and I have to take the test tomorrow...

neon iron
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@ruby wedge i can take over if ur ok with it

ruby wedge
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@neon iron thanks man

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yeah go ahead

smoky pivot
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Oh shoot- sorry dude

neon iron
#

alr alr i got u

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what u need

ruby wedge
smoky pivot
#

Where do I even begin...

neon iron
#

ur good dw

smoky pivot
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What are the odds I finish this all before the test tommorow?

neon iron
#

100%

smoky pivot
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I mean I can take it at any time- I just have a time limit...

neon iron
#

u can do this

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let me try to help?

smoky pivot
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Sure

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Ok eh...

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So here we are with this

neon iron
#

ok so we're looking for the graphs intersect right

smoky pivot
#

Yes

neon iron
#

and how many points are there where they intersect

smoky pivot
#

One

neon iron
#

so what choices can we eliminate

smoky pivot
#

A

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C

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D

neon iron
#

so whats the answer

smoky pivot
#

Wait- do I need to plug in the equation?

neon iron
#

are u looking for the y value

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or the coordinate of intersection

smoky pivot
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Im looking for the solution to y1=y2 apparently

neon iron
#

well yes ik that

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but have the previous problems asked for a coordinate

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or just a y value

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i just searched it up

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B is the answer yes

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just the x value

smoky pivot
#

Ehhh now I need solution set for y1 < y2?

neon iron
#

send me the problems pls

smoky pivot
neon iron
#

alr so we're looking for where y2 > y1

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what curve is y2

smoky pivot
#

Its a line ?

neon iron
#

its still called a curve

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whcih one

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the red or the blue

smoky pivot
#

The red?

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Im so confused...

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The one with absolute value is the only curve I thought

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The blue one

neon iron
#

theyre both curves

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but yes red is y2

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is y2 ever greater than y1

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@smoky pivot

smoky pivot
#

Yes

neon iron
#

where

smoky pivot
#

Where is the y1?

neon iron
#

y1 is the blue function

smoky pivot
#

So Im not trying to simplify y1?

neon iron
#

whyd u do that 🆘

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😭

smoky pivot
#

Im going to assume Im over thinking this again💀👍

neon iron
#

yea

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why woudl u do that 🆘

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😭

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look at the graph

ruby wedge
#

you are trying to find what values of x make the blue function greater than the red

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im back

neon iron
#

is the red curve above the blue curve

smoky pivot
#

To see if its its then y2???

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At least I think my notes say something?

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No the blue is above

ruby wedge
#

good

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at what values of x

smoky pivot
#

The value of x is... theres no written number

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But Im going to say 2?...

ruby wedge
#

there are various values of x where the blue is larger

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so it has to be an interval

neon iron
#

well i mean u can sorta look and see that the red is never above the blue

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and then use process of elimination

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no?

ruby wedge
#

yeah

smoky pivot
#

So 1 and -1?

ruby wedge
#

no

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look where is y_1=y_2

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you answered it

smoky pivot
#

So its 1 again???

ruby wedge
#

no

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wait

neon iron
#

but at 1 theyre equal

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not greater than

ruby wedge
#

so at every other point it is greater

ruby wedge
#

what answer encompasses every x value except 1

ruby wedge
#

@neon iron lowkey this is becoming a two person job

neon iron
#

yea yea ik 😭

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im down for it tho

ruby wedge
#

yeah fs

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i was just helping someone else

ruby wedge
#

lol

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anyway you didnt answer my question

smoky pivot
#

The example is no help either

neon iron
#

alr arl rainbow

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calm down

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what does greater mean

smoky pivot
neon iron
#

yes

neon iron
ruby wedge
#

yes but not what i was lookin for

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its okay tho

smoky pivot
#

I wanna just say theres no solution

ruby wedge
#

there is

smoky pivot
#

But its probably A?...

ruby wedge
#

yes

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but lets undertsnad

neon iron
#

umm yk what A means?

ruby wedge
#

yeah lets not guess

smoky pivot
#

I dont understand how its 1 and 1 when then line isnt even on the orgin

neon iron
#

what does that have to do with the origin

smoky pivot
neon iron
#

thats not the origin

smoky pivot
#

HOW IS THAT 1

neon iron
#

ummm look at the x axis

smoky pivot
#

...

ruby wedge
#

it goes by 2

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so half is 1

#

lets go back to the basics you have a function right? the function has an input and output essentially the input (x) value dictates the output (y) the height of the function so if the height of the blue function is higher than red one there are x values that make that true you want to find those

#

x values that make the blue function greater than the red which is all of them except for 1 because they are equal to eachother at that point

neon iron
#

@ruby wedge u got this

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im not quiite the teacher u are 😭

ruby wedge
#

lol

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its okay

smoky pivot
#

Thank you for trying💀⚰😭

ruby wedge
#

i have taught before so

smoky pivot
#

@neon iron I appreciate it

ruby wedge
#

alright you and me again

smoky pivot
#

Ok ok maybe A visual would help?

ruby wedge
#

alright let me make one real quick

smoky pivot
#

Or maybe I should get back to this question later

smoky pivot
ruby wedge
#

nah i just need you to understand why it is a

smoky pivot
#

I want to as well but the puzzle is not piecing

ruby wedge
#

did you read my explanation

neon iron
smoky pivot
#

I did

#

I do

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And I will do

ruby wedge
#

the range is that one

#

maybe its the wrong letter mb

smoky pivot
#

But its not... I need a visual

ruby wedge
#

but its the one that excludes 1

neon iron
#

mb mb

ruby wedge
#

ok ok

neon iron
#

im tuned to domain for intervals 😭

ruby wedge
#

lol its okay

smoky pivot
#

Ok

#

So...

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Are we sure we shouldnt simplify the absolute value?

neon iron
#

how would u do that

smoky pivot
#

Probably not

neon iron
#

how is that even possible 😭

smoky pivot
#

Hold on its in my notes

neon iron
#

💀

ruby wedge
#

icant make a visual

#

plus im more of an analytical person

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anyway you dont need to do anything to the function

smoky pivot
#

I am also analytical... in the most useless way right now

neon iron
#

its literally graphed 😭 why would u want to work with the actual equations

ruby wedge
#

we found out that when x=1 , y_1 is equal to y_2

neon iron
#

yes

smoky pivot
#

I dont know maybe it would give me a sense of control or something 💀

neon iron
#

yea but hows that hlep

ruby wedge
#

so at every other x the blue function is larger than the red

smoky pivot
#

I cant figure out where the negative one is from

ruby wedge
#

so there are two intervals where the blue is larger (-infty,1) and (1,infty)

smoky pivot
#

Ohhh...

ruby wedge
#

if you combine them (union) then you get the answer a

smoky pivot
#

So the answer is A....

ruby wedge
#

yes

#

do you somewhat understand

smoky pivot
#

I was focused on the numbers and point its self

ruby wedge
#

i think thats your issue

#

you need to be holistic

smoky pivot
#

Computer saying incorrect

ruby wedge
#

really?

#

show me

smoky pivot
ruby wedge
#

oh so we are looking for the opposite mb

smoky pivot
ruby wedge
#

lol

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which one is y_1

smoky pivot
#

The opposite makes more sense then this one

neon iron
#

It’s indefinite 😭

#

Istg I said this

smoky pivot
#

I just wanna put no solution so bad

ruby wedge
#

if the blue one is y_1 then it is no solution

smoky pivot
#

Because tell me where a -1 just appears from

neon iron
#

Rainbow what grade r u in

ruby wedge
#

prolly highschool

smoky pivot
#

College algebra

ruby wedge
#

thats a class

#

so you are implying you are in college

smoky pivot
#

Yes

neon iron
#

Well I’d think so

ruby wedge
#

okay probably a freshman

smoky pivot
#

I havent done math since I graduated school 4 years ago 💀

ruby wedge
#

damn

neon iron
#

Oh 4 gal yrs?

#

Gap yrs?

ruby wedge
#

@neon iron what was the highest math you studied or studying

smoky pivot
#

I failed the first test because it started with a camera looking at me a timer and a white screen - suddenly all that I spent weeks learning just- poof...

neon iron
#

I’m uhh doing abstract algebra rn… I’m at a private hs and they let me do classes at a local community college

#

I’m actually doubling

ruby wedge
#

me too

neon iron
#

Abstract with discrete math

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Fun stuff

#

Not a fan of discrete icl

smoky pivot
neon iron
smoky pivot
#

I used to be good at this...

neon iron
#

Or as in ur hs let’s u take classes at a local college

smoky pivot
#

I did dual enrollment

smoky pivot
#

But in my final year (because transportation issues)

ruby wedge
smoky pivot
#

Also covid did a number

ruby wedge
#

yeah

#

I graduate this year

neon iron
#

Oh I’m a sophomore 😭

ruby wedge
#

applied to MIT a few days ago

smoky pivot
#

Oh my gosh there it no solution this entire time...

neon iron
#

Nice nice

#

That’s where my dad went… before he dropped out

#

That’s the dream tho

smoky pivot
#

Congrats

neon iron
#

Mit or caltech

smoky pivot
#

Hope you get in

ruby wedge
#

yeah wish me luck

neon iron
#

Good luck man

ruby wedge
neon iron
#

Nah I’m saying those are the dreams

#

MIT caltech or Stanford

ruby wedge
#

oh yeah fs

neon iron
#

My brothers at Princeton for physics rn

#

That’s sick asf icl

smoky pivot
#

I should have just put no solution from the start💀

ruby wedge
#

yeah

smoky pivot
#

This entire time I spent...

ruby wedge
neon iron
#

Umm great parents

ruby wedge
#

im the outstadning one in my family

neon iron
#

Yea

ruby wedge
#

gotta represent

neon iron
#

It’s hard to be outstanding here

#

In comparison 😭

ruby wedge
#

lol i have fun with it, its competition

neon iron
#

Hey but pressure makes diamonds

smoky pivot
#

I have a diagnosed learning disability:D

neon iron
#

Pressure is a privilege

neon iron
smoky pivot
#

Maybe 2.. other ones

ruby wedge
#

holy bomb drop

smoky pivot
#

But thats not offical yet

neon iron
#

@ruby wedge can I friend u

ruby wedge
#

fs

smoky pivot
#

You guys have no learning struggles? If so, I'm glad for you

ruby wedge
#

i dont

#

well kinda

#

i have autism but it actaully helps me

#

hyperfixiation

smoky pivot
#

I might have autism- I mean everyone seems to ask me if I do (and its never jokingly) buttt its a shame the possible benefits are cancled out by the Adhd._.

#

I get the hyperfixations - but only if they give a LOT of dopamine

#

Anyway back to math

#

Im now dealing with... this.

#

Oh wait I might-...

#

Nope.

#

@ruby wedge @neon iron sorry for getting off topic

ruby wedge
#

your are good

neon iron
#

Rainbow

#

Do yk how to solve abs value inequalities

smoky pivot
#

I believe so but let me just test this one and if I do I will skip and work on this specific part tomorrow

neon iron
#

Alr alr

smoky pivot
#

I think I do something like...this

neon iron
#

Alr alr

smoky pivot
#

Now I think I gotta check

neon iron
#

Good job

smoky pivot
#

x can technically be both

#

After checking

#

So would that make the solution set (6,-12)?

neon iron
#

Yea

smoky pivot
#

Im going to guess its not points so its the finite number set with these{} instead of ()

neon iron
#

Yea

smoky pivot
#

Ok so... apparently thats wrong

#

What did I do wrong here?...

ruby wedge
#

lowkey i havent done this in a while so idek

neon iron
#

Show me the answer choices

smoky pivot
#

Im wondering if I should try to finish this tonight or if I should pick it up tomorrow with a fresh mind- even though well- the test is tomorrow.

neon iron
#

Ok did u solve all 3 inequalities

#

Or just the first one

smoky pivot
#

I wish at the very least we could keep basic formula notes next to us

#

Ah- the first one.

#

I see

#

Hm...

ruby wedge
#

i would say pick it up tmrw

smoky pivot
#

Yeah I feel like the later it is the more things are... slipping like... sand perhaps

#

I'm just nervous

#

I didn't anticipate that my plan to work on the second chap through the week would get interupted by 4 days sick

neon iron
#

It’s alr u got this

smoky pivot
#

Thank you

#

It is 01:30 right now

ruby wedge
#

yout welcome

smoky pivot
#

Maybe its is best to pick it up early tomorrow

ruby wedge
#

yup

smoky pivot
#

Thank you so much for the help

#

I imagine I took up alot of your time

#

@neon iron @ruby wedge Hope you have a good day/evening

#

I should probably close this up for now right?

ruby wedge
#

yup

#

goodluck

smoky pivot
#

Thanks

#

.close

topaz sinewBOT
#
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sturdy fulcrum
#

Hello. I wanted to solve Hatcher's Algebraic Topology exercise 1.1.1.

clear python
#

Send an image of the question please

sturdy fulcrum
#

It says, show that composition of paths satisfies the following cancelation property: If $f_0 * g_0 \simeq f_1 * g_1$ and $g_0 \simeq g_1$ then $f_0 \simeq f_1$

thorny flameBOT
#

Gol D Roger

sturdy fulcrum
#

I need to construct the homotopy, but Idk where to begin

#

To be more precise, the question is this:

clear python
sturdy fulcrum
#

<@&286206848099549185>

elfin bridge
#

Well you can compose with the inverse path of g0 on the right of both sides

sturdy fulcrum
#

Like $ f_0 \circ g_0 \circ g_0^{-1} \simeq f_1 \circ g_1 \circ g_0^{-1}$?

elfin bridge
#

Ye

sturdy fulcrum
#

Ok, I suppose the left side is homotopic to $f_0$. What happens to the right side?

thorny flameBOT
#

Gol D Roger

sturdy fulcrum
#

Since $g_1$ and $g_0$ are fundamentally distinct

thorny flameBOT
#

Gol D Roger

elfin bridge
#

Well theyre given to be homotopic here

#

Since theyre homotopic endpoints are fixed right

sturdy fulcrum
#

Yeah

elfin bridge
#

Idk if this was mentioned in the text also but if g_0 homotopic to g_1, then g_0, then g_0 o f is homotopic to g_1 o f

So therefore g_1 o (g_0)^-1 (using this inverse notation) is homotopic to identity

#

I dont have the latex off the top of my head sorry

sturdy fulcrum
#

Don't worry, I think I understood what you mean

sturdy fulcrum
#

Since I think is using what I need to prove

#

Like, the composition property

#

Of homotopic paths

elfin bridge
#

This one isnt too bad, you just find a homotopy X x I -> Z given f: X->Y and a homotopy H: Y x I -> Z (between g_0, g_1)

Namely you take H and you precompose it with a function f x Id_I: X x I -> Y x I, (x, c) |-> (f(x), c)

So H o (f x Id_I) is a homotopy X x I -> Z (you can verify this)

sturdy fulcrum
#

Ok, I'll write it then. If I conclude it I will close. Thanks for the idea

elfin bridge
#

Theres a similar one but with postcomposition which you might need to finish the proof too

sturdy fulcrum
#

Which one is that?

elfin bridge
#

Like f o g_0 is homotopic to f o g_1

#

If g_0 is homotopic to g_1

#

The proof is entirely analogous you just postcompose with f

sturdy fulcrum
#

So, what you say is to prove composition left and right are the same?

elfin bridge
#

No so like what im thinking here is

We have that id is homotopic to g_1 o (g_0)^-1

Thus using that, we would have that f_0 homotopic to f_1 o g_1 o (g_0)^-1 is homotopic to f_1 o id -> f0 homotopic to f1

You'll need to check this is true by verifying the endpoints are the same

#

Which should be true by defn of homotopy anyways

sturdy fulcrum
#

Oh I see

#

But, checking that would mean giving the homotopy?

elfin bridge
#

So from this you could construct an explicit homotopy sure

#

But you dont necessarily need to write out the homotopy to show things are homotopic (this method doesnt really require an explicit homotopy to be constructed)

sturdy fulcrum
#

Wow, that's really nice to read

#

Ok, I'm going to fill the details on what you've told me.

#

I will close as soon as I'm done

topaz sinewBOT
#

@sturdy fulcrum Has your question been resolved?

#
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red sky
#

<@&286206848099549185>

topaz sinewBOT
finite storm
#

nah

red sky
#

Too early?

finite storm
#

first send problem

#

second wait 15 min

red sky
#

,rccw

thorny flameBOT
red sky
#

45

#

How many positive numbers are in the arithmetic progression

left juniper
#

!status

topaz sinewBOT
#
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
red sky
#

2

left juniper
#

Send us your best attempt

red sky
#

,rccw

thorny flameBOT
red sky
#

Absolute nonsence

late aspen
# red sky ,rccw

it's a sequence of odd numbers starting from 175 and going backwards

red sky
#

Yes ik the answer but I need a way to write it

late aspen
#

positive so T(n) > 0

#

175 - 2(n - 1) > 0

#

175 - 2n + 2 > 0

#

177 - 2n > 0

#

2n < 177

red sky
#

Thank you

late aspen
#

n < 88.5

late aspen
left juniper
#

Don't give full answer, please? Give hints instead

red sky
#

Also the answer is 88, but I get 88.5 so yea

#

Don't know if that counts

#

Bc 89 is also an option but it's wrong

left juniper
#

What is the value at index 89?

red sky
#

I imagine a negative number

#

Bc it's n<88.5

left juniper
#

Yes. So you know that the number at index 1 to 88 is positive

red sky
#

Oh

#

Okay thank you

#

Have a nice day man

#

.close

topaz sinewBOT
#
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dark quest
#

can someone explain to me how you are supposed to get the x = expression please?

dark quest
#

@haughty drum

opal vault
#

so, we only need to find an irrational number between a and a+1, because then dividing by b makes it an irrational number between a/b and (a+1)/b

#

so, we only need to find an irrational number between 0 and 1, because then adding a...

#

so... pick your favorite irrational number between 0 and 1

#

any will work (so 1/sqrt(2) = sqrt(2)/2 works for example)

opal vault
#

(and wait 15min before using that ping)

dark quest
#

ah ok thank you for answering back I thought there was a special reason for picking sqrt2

#

also i didn't realize i pinged the wrong ping sorry

dark quest
blissful needle
dark quest
#

split it into numerator and denom?

opal vault
#

and (a+1)/b = a/b + 1/b

#

if we want an irrational $I$ such that $\frac{a}{b} < I < \frac cb$

dark quest
#

why is it important to make the distinction of (a+1)/b

thorny flameBOT
#

Raphaelisius Maximus MMIII

opal vault
#

since we have $\frac{a}{b} < \frac{a+1}{b} \leq \frac cb$

thorny flameBOT
#

Raphaelisius Maximus MMIII

opal vault
#

if we manage to find an irrational $I$ such that $\frac{a}{b} < I < \frac{a+1}{b}$

thorny flameBOT
#

Raphaelisius Maximus MMIII

opal vault
#

then we win

#

is this ok so far?

dark quest
#

uh

#

i see than we reduced the scope of our problem to between a and a+1

opal vault
dark quest
#

yeah

opal vault
#

and then between a and a+1 as we multiply by b

dark quest
#

yeah

opal vault
#

(and then between 0 and 1 as we subtract a)

dark quest
#

wait what

#

what's between 0 and 1

#

and why are we subtracting a

opal vault
#

if it helps you we can do it

#

since a is rational (an integer)

#

if we have an irrational I between 0 and 1

#

then a + I is an irrational between a and a+1

#

and we win

dark quest
#

then why is c

#

why is there a a<c

#

and c/b?

opal vault
#

c/b ?

#

ok wait

#

remember we forgot about c?

dark quest
#

yeh

opal vault
#

when we said we only need an irrational between a/b and (a+1)/b

#

it's this portion that explains it

dark quest
#

why do we need to metion c if all we need is a+1 and a

opal vault
dark quest
#

whut

#

if we don't need c we need to prove that we dont need c by saying c exists?

#

im very confused

opal vault
#

let's start from the beginning

#

we want to show there is an irrational between any two rationals

#

so... take a/b < c/d any rational numbers

#

"d" isn't needed, because we can take a common denominator

#

so take a/b and c/b with a < c

dark quest
#

yes

opal vault
#

since we have $\frac ab < \frac{a+1}{b} \leq \frac{c}{b}$, we can be even pickier and ask to find an irrational between $\frac ab$ and $\frac{a+1}{b}$

thorny flameBOT
#

Raphaelisius Maximus MMIII

opal vault
#

because in that case it'll be between $\frac ab$ and $\frac cb$

thorny flameBOT
#

Raphaelisius Maximus MMIII

opal vault
#

so we don't need "c/b" anymore

#

see how this lets us simplify the problem step by step

dark quest
#

ok

opal vault
#

we needed to justify every step

#

but now we don't need "d", and now we don't need "c" anymore

#

now let's push this further

#

saying we don't need "b", because if we find an irrational between a and a+1, then just divide by b

#

but we don't need "a" either, because if we find an irrational between 0 and 1, then just add a

wintry meteor
#

-# Side discussion: Is the wording in the question is wrong? I think it should say “Between every two distinct rational numbers”

opal vault
opal vault
dark quest
#

no i think i get it now

#

my only problem with reading the solution was like

opal vault
#

alright

dark quest
#

trying to figure out how I'm supposed to come to the proof by myself

#

im studying for a exam and i am not very confident in proofs

#

and its very late at night lol

opal vault
dark quest
#

i get the problem now though tyvm

opal vault
#

less variables = easier problem

dark quest
#

ok i will try to remember that for tomorrow sadcatthumbsup

topaz sinewBOT
#

@dark quest Has your question been resolved?

topaz sinewBOT
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graceful cove
#

I see that 10! is the total amount of outcomes and somewhat see that 4!3!2!1! represent the amount of repeats we have but since there are four different nationalities shouldn't there be 4! ways of getting these extra counts so shouldn't it be 10!/4!4!3!2!1! instead of 10!/4!3!2!1!

topaz sinewBOT
#

@graceful cove Has your question been resolved?

craggy haven
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rancid laurel
#

hi, why is this k value not a solution?

rancid laurel
#

thanks in advance.

#

according to the conclusion in my book, only k = 1.975 is the right answer

fallow heart
#

Because that basically corresponds to k = 0, which would give you the function f(x) = 1. But the integral of this between 0 and 1 doesn't equal π

#

k being something like 10^-15 is very likely an index of a numerical error

rancid laurel
#

thanks

#

.close

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#
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autumn timber
#

can someone give me introduction into proving things in maths with short example?

topaz sinewBOT
#

@autumn timber Has your question been resolved?

topaz sinewBOT
#

@autumn timber Has your question been resolved?

junior scarab
#

What is the problem?

topaz sinewBOT
#

@autumn timber Has your question been resolved?

autumn timber
quasi depot
#

A proof is a sequence of logical steps that start from axioms, and use what you already know to make logical implications

#

An example that you should be familiar with is solving equations

#

lets say you are given the equation x^2 - 2x + 1 = 0

#

by solving the equation in the real numbers (and providing all of the steps) you prove the statement "if x is a real number, then x^2-2x+1=0 if and only if x=1"

autumn timber
quasi depot
#

wdym?

clear lodge
#

define "the fancy stuff"?

topaz sinewBOT
#

@autumn timber Has your question been resolved?

autumn timber
inland mica
#

it depends on your level of math

#

usually when you learn math, there will be assumptions you need to make, so as not to prove everything from the ground up every time you want to use a result

#

for example, you will never have to prove that 1+1 = 2 when taking calculus courses because it is accepted as true, and because the point of the course is not to prove it again

#

in short, you don't need any fancy stuff to write a proof, it just needs to be logically sound

autumn timber
#

more like how many exist and find something

#

also there were a lot of geometry proof, so yeah

clear lodge
#

as bloubb has stated, it really depends on what you're allowed or assumed known at that point.
You usually prove stuff not from ground up, but from what is assumed known.
In geometry, for example, you'd be allowed to use pythagora's theorem, without any need to prove it, because it's assumed known

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#

@autumn timber Has your question been resolved?

topaz sinewBOT
#
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true fulcrum
topaz sinewBOT
true fulcrum
#

.rotate

hardy wing
thorny flameBOT
true fulcrum
#

ok so im at the last step but im a lil confused

#

why is x =4 or =0? its not exactly clicking

#

btw hello

#

forgot to be polite

hardy wing
#

$f'(x) = 3x(x-4)$, a critical point is when $f'(x) = 0$, so you find the values of x where $3x(x-4) = 0$

thorny flameBOT
#

Stitches

hardy wing
#

Or do you not understand why 3x(x-4) = 0 when x = 0 or 4?

true fulcrum
#

so this is saying that hwen the derivative of a function is = 0 meaning 0 slope meaning 0 change we must find the values of x this happens at?

true fulcrum
#

i get the factor

#

the the derivative

#

and the derivative

hardy wing
#

Yes. The derivative of a function being 0 means that the slope is 0. This might correspond to a maximum (thing tip of a parabola), a minimum (think bottom of an upside down parabola, or an inflection/saddle point (ie. neither, think x^3 at x = 0)

true fulcrum
#

what exactly is an inflection - a kind of center on the parabola?

#

its just why is x = 0 or 4?

lucid junco
true fulcrum
#

sure that makes sense

#

but how do you arrive at x=0 or x= 4

lucid junco
#

so you’re not confused about how to get f’(x) itself just why x=0,4 ?

true fulcrum
#

yes

lucid junco
#

if a*b=0 then either a=0 or b=0

#

It’s called the zero product property

true fulcrum
#

right

#

ah

#

ah

#

yes i see now

lucid junco
#

You have done quadratics before ? It is the same thing as that

true fulcrum
#

thanks

true fulcrum
#

but i understand now thanks

#

.close

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#
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#
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winged basin
#

I am preparing for a linear algebra test, where I am allowed to use python. I have a problem with linear codes.


import numpy as np 

def p1_of_list(bits):
    return (bits[1]+bits[0]+bits[2])%2

def p2_of_list(bits):
    return (bits[1]+bits[0]+bits[3])%2


def p3_of_list(bits):
    return (bits[0]+bits[3]+bits[2])%2

def generate_paritycheck_matrix(n,k):
    A = np.zeros((k,n-k))
    index = 0
    for bits in np.identity(k):
        A[index][0] = p1_of_list(bits)
        A[index][1] = p2_of_list(bits)
        A[index][2] = p3_of_list(bits)
        index = index + 1
    return A

def generate_generator_matrix(n,k):
    return np.hstack((np.eye(k), generate_paritycheck_matrix(n,k)))

#from here it does not make any sense
n,k = 7,4
data = np.array([[0,0,1,1]])
hamming = np.dot(data, generate_generator_matrix(n,k))


parity_check_matrix = np.hstack((generate_partycheck_matrix(n,k).T,np.eye(k-1)))
np.dot(parity_check_matrix, hamming.T) 
winged basin
#

The result of the last line is:

array([[2.],
       [2.],
       [4.]])

Which makes no sense to me, this should give index of the column that contains the error, no?

#

or in this case it should be 0, no?

zinc holly
#

Ayo

winged basin
#

I am super afraid I don't get the theory

topaz sinewBOT
#

@winged basin Has your question been resolved?

topaz sinewBOT
#

@winged basin Has your question been resolved?

winged basin
#

This isn't an exercise, but I guess the question would be: Implement a linear Code System, which can generate the generator matrix, parity check matrix and check sent hamming codes.

topaz sinewBOT
#

@winged basin Has your question been resolved?

topaz sinewBOT
#
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grand solar
#

have a question about these two questions

topaz sinewBOT
grand solar
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why does one specify prime power order and the other doesnt

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also can it be done without a calulcator

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I was just going to find the orders of most of the elements to elminate which groups its not isomorphic to

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for 27 G can be isomophic to either $Z_{16}$ or $Z_8 \oplus Z_2$ or $Z_4 \oplus Z_4$ or $Z_4 \oplus Z_2 \oplus Z_2$ or $Z_2 \oplus Z_2 \oplus Z_2 \oplus Z_2$

thorny flameBOT
#

Branshi

grand solar
#

.close

topaz sinewBOT
#
Channel closed

Closed by @grand solar

Use .reopen if this was a mistake.

topaz sinewBOT
#
Available help channel!

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pulsar forum
#

Hi, I'm Italian, I need help with maths, anyone speak Italian?

spare smelt
#

Mama mia

pulsar forum
drifting swift
drifting swift
pulsar forum
pulsar forum
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I have a rational function x^3+x/3x. I can study the limits, but I can’t find the first and second derivatives, and I can’t plot it on the Cartesian plane.

whole slate
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what’s bothering you?

pulsar forum
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When I get to the first derivative, I can’t go any further. I could try to send a photo, but I’m not sure if you can read my writing.

whole slate
#

please send

pulsar forum
topaz sinewBOT
#

@pulsar forum Has your question been resolved?

clear python
#

Could you turn on the lights and send another picture

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,rccw

thorny flameBOT
pulsar forum
#

There are limits shown at the top of the page, but please ignore them

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The sign study is wrong, ignore that too. I corrected it on another page.

topaz sinewBOT
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@pulsar forum Has your question been resolved?

topaz sinewBOT
#

@pulsar forum Has your question been resolved?

shy wolf
# pulsar forum

I'm sorry I can't really speak italian, but in that problem you can cancel the x in the denominator and numerator, when $x\neq 0$, so it should be easier to calculate the derivatives that way. If you choose to use the quotient rule anyways, you've made some mistakes while substituting the derivatives in the formula, it should end up being $\frac{(3x^2+1)(3x)-(x^3+x)(3)}{(3x)^2}=\frac{2x^3}{3x^2}$

thorny flameBOT
#

KonoEmllikDa

topaz sinewBOT
#

@pulsar forum Has your question been resolved?

topaz sinewBOT
#
Channel closed

Closed due to timeout

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topaz sinewBOT
#
Available help channel!

Send your question here to claim the channel.

Remember:
Ask your math question in a clear, concise manner.
Show your work, and if possible, explain where you are stuck.
Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!

Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.