#help-13

1 messages · Page 408 of 1

past jungle
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i see, so can't use question assumptions during a proof

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guess I'm worried in case a question appears where it's true, idk how i would approach that without using assumptions given in the question

dreamy sleet
past jungle
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oh shit right, yeah that.

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mb

dreamy sleet
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“P(A|B) =< P(A)” is not an assumption

past jungle
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👍

dreamy sleet
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So just be very clear about what’s an assumption and what’s the goal/conclusion

cedar kilnBOT
#
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remote parcel
cedar kilnBOT
remote parcel
#

I just need some pointers on how to get started

#

this is what I tried thus far but to no avail

remote parcel
# remote parcel

I know that any vector that's the linear combination of v1... vk can be expressed as A(v1) +... A(vk) or A(v1+...vk) but I don't know if it helps

next cloak
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You need to show the equivalency of sets

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take any vector from R^m and prove that it can be written as that span

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you know that any vector in R

remote parcel
next cloak
#

Okay so: Any vector in R

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sorry my keyboard is interrupting my texts

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Any vector in R^m can be written as the linear combination of vectors in R^n and A. So to speak: You can get any vector in R^m by a multiplication A.v , where v is a vector in R^n.

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And you can get any vector in R^n by the span of (v1, .... vk)

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If you can get any vector in R^n with that basis, When you multiply it with A and take the linear combination you can get any vector in R^m

next cloak
remote parcel
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Wait, I'm trying to work it out

next cloak
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I wrote a solution to the paper

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if you want i can send you

remote parcel
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sure

next cloak
#

can you open it?

remote parcel
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yes am viewing it

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I'm almost mentally there

next cloak
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So A.w = v is because of Rank = m

remote parcel
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So we have a vector v, in R^m space

next cloak
#

Yes and because the rank is full we can write it as an output of A and a random vector

remote parcel
#

Because of A being rank m, there exists some w such that Aw=v

next cloak
#

Exactly

remote parcel
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And because the span of v1,...vk is R^n, w is a linear combination of those

next cloak
#

yess

remote parcel
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And this works for any v, which means that the span of Av1,... Avk is the exact same as R^m

next cloak
#

yes

remote parcel
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Because A is basically a translator between R^n and R^m

next cloak
#

Yeah

remote parcel
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Alright, thank you

#

That was quite clear

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.close

cedar kilnBOT
#
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next cloak
cedar kilnBOT
next cloak
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.close

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drowsy obsidian
cedar kilnBOT
drowsy obsidian
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why should i do this

prisma pike
drowsy obsidian
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by parts?

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but how would i think of this approach

cedar kilnBOT
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@drowsy obsidian Has your question been resolved?

drowsy obsidian
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<@&286206848099549185>

regal talon
cedar kilnBOT
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@drowsy obsidian Has your question been resolved?

drowsy obsidian
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.close

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crisp thorn
#

Hey guys. I'm writing my IB math IA right now, and I wanted to compare three different attempts to model caffeine in the body using the Akaike information criterion. Namely, the michaelis menten equation (given by v = (Vmax*[s]) / (Km +[s]) where Vmax and Km remain constant), a first-order one-compartment model ( given by C(t) = (D*Ka) / (Vd(Ka-Ke)) * e^(−ke​(t))−e^(−ka(​t)). Where every parameter(?) is a constant ) and finally a polynomial regression model ( as y=β0​+β1​x+β2​x2+β3​x3+⋯+βn​xn+ε ). I'm learning stats and modelling basics for the very first time so please forgive me if im forgetting important information or giving unimportant ones. However, I read on the math stack exchange that if I'm comparing non-nested models like these, I shouldn't be using the AIC in Ripley's school of thought. Is he right in stating that, or for my purposes am I safe to use the AIC to determine the best fitting model?

https://mathoverflow.net/questions/249448/use-of-akaike-information-criterion-with-nonnested-models/249753#249753

cedar kilnBOT
#

@crisp thorn Has your question been resolved?

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crude brook
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How do we call the red and blue lines in english? Sorry but my english terminology isn't very good

dreamy void
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Isn't the blue a bisector and red a perpendicular?

crude brook
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αα διχοτομος right

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the blue one

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the red line segment splits the bottom and the top line segment into 2 equal line segments

crude brook
dreamy void
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never heard that before

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apparently there is perpendicular and angle bisections

crude brook
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if they don't form right angles how are they called?

dreamy void
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acute and obtuse angles?

crude brook
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no i mean the red line segment would be a perpendiculer if it formed right angles with the other line segments, how would it be called if it just went through the middle of the other line segments?

stiff totem
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just a bisector, or line segment bisector

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blue is an angle bisector

crude brook
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Ahh ok thank you

crude brook
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.close

cedar kilnBOT
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dreamy void
cedar kilnBOT
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viral fox
#

Hi, would you mind helping me understand the following sentence please? (I'm an undergrad student)

We also prove that if X and Y are complex normed spaces with dim(X) ≥ 2 and X admits a conjugation τ (i.e., a period-2 conjugate linear isometry), then every additive mapping A : X → Y preserving Birkhoff orthogonality is real-linear.
This is from the paper "Additive mappings preserving orthogonality between complex inner product spaces" (https://www.sciencedirect.com/science/article/pii/S0024379525000485?via%3Dihub). page 450

I don't understand the "X admits a conjugation τ" part, and its example as "a period-2 conjugate linear isometry"
Thanks.

crimson delta
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a map f:X->X with f^2=id, f(cx)=conj(c)f(x) and f(x+y)=f(x)+f(y) and ||f(x)-f(y)|| = ||x-y||

viral fox
crimson delta
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f(f(x))=x

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antilinear and conjugate linear maps are the same, yes

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its just a generalization of what the normal conjugation as a map C->C does

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if we view C as a normed R vector space

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doing it twice does nothing, is linear, doesnt change distances

viral fox
crimson delta
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aka multiplying by -1

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yes

viral fox
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Awesome, thanks. really really appreciate your time sir.
Math bless us all.🤘🍻🤓

#

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cedar kilnBOT
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stiff bloom
#

What is the simplest method / formula to find the sine or cosine of an angle Theta with the access of a calculator? (Excluding the common function)

crimson delta
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using the sin/cos button

stiff bloom
crimson delta
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why

inland ether
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no use probably

stiff bloom
# crimson delta why

curious if it's possible. I'm committing to a MAP test tomorrow and I want any second-hand methtod

crimson delta
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just dont

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waste of time

stiff bloom
oblique flare
inland ether
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manually it is more feasable uk

crimson delta
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well of course there are methods. you can do what the calculator does

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but it will be slower

inland ether
crimson delta
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and just not worth it

lofty sand
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To approximate it

stiff bloom
lofty sand
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Or you can draw the angle, measure the sides of the triangle and just do the relevant fraction

oblique flare
inland ether
lofty sand
stiff bloom
lofty sand
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I need to understand your use case better. Is it for an exam ? Do you have a specific sin/cos to find ? Or do you just imagine travelling back in time and having to compute trig to build a caveman’s house ?

stiff bloom
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the more I iterate, the more precise the result is?

stiff bloom
oblique flare
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if the angle is small enough (x in radians) just use
sinx=x and cosx=1-x^2/2

lofty sand
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You should learn your usual trig and then use relevant formulas to solve …

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This is what they’re expecting here

crimson delta
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this is just a waste of test time

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no test will require you to do this

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use the time to go over the other questions again

stiff bloom
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I remember 1 question back in g7

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it probably costed me 3 points

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in the MAP

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I was working with 251-261 territory scores

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rn I'm working 261+

native heath
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what question lol

crimson delta
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ther was a question in g7 (whatever that means) that required you to compute a sin without a proper calculator worth 3 points?

stiff bloom
crimson delta
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this just feels like you messed up the question

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and there was an easier way

stiff bloom
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270 is 2 times better than 240

timid basin
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guys whats the interval that this function is increasing?

stiff bloom
cedar kilnBOT
timid basin
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sorry guys

cedar kilnBOT
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@stiff bloom Has your question been resolved?

stiff bloom
#

Yes

cedar kilnBOT
#
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cedar kilnBOT
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supple falcon
#

I need help solving this system of equations

supple falcon
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$\begin{cases} x(x + 2)(2x + y) = 9 \ x^2 + 4x + y = 6 \end{cases}$ for $x, y \in \mathbb R$

wraith daggerBOT
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1 divided by 0 equals Infinity

supple falcon
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how

queen stirrup
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x^2 + 4x + y = x(x+2) + 2x+y

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now do

supple falcon
wicked mantle
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That’s insightful, impressive that you find it fast

queen stirrup
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clearly some substitution has to be made

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so to make the second equation similar to the first

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you can write x^2 + 4x + y = x^2 + 2x + 2x + y

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(to get 2x+y)

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furthermore

supple falcon
queen stirrup
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x^2+2x = x(x+2)

queen stirrup
supple falcon
supple falcon
wraith daggerBOT
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1 divided by 0 equals Infinity

queen stirrup
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yeah you can solve for a and b

supple falcon
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where $a = x(x + 2)$ and $b = 2x + y$

wraith daggerBOT
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1 divided by 0 equals Infinity

supple falcon
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great method

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thanks

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i'll need more help later

queen stirrup
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:)

old swan
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beautifully done

supple falcon
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lol

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how about $\begin{cases} (x + 6y)(3x + 2y) = 12 \ 2x^3 + 6y^3 + 15x^2y + 19y^2x + x + 6y = 12 \end{cases}$

wraith daggerBOT
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1 divided by 0 equals Infinity

supple falcon
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i saw i wanted $3x + 2y$ in (2) im thinking

wraith daggerBOT
#

1 divided by 0 equals Infinity

supple falcon
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and i had $x + 6y$

wraith daggerBOT
#

1 divided by 0 equals Infinity

timber arrow
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Im looking at a potential x+6y in the cubic and linear terms, can you go from there?

supple falcon
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oh okay

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wait a moment

timber arrow
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You can also set the equations equal to each other since they both equal 12

supple falcon
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i don't know if that will work

timber arrow
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why not

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A=12 and B=12 implies A=B

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it may not be helpful but you can certainly try

queen stirrup
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try to do long division after you equate them

supple falcon
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polynomial division

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it's been a long time since i've visited that

queen stirrup
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left side is divisible

supple falcon
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like a year or smth

queen stirrup
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its not that difficult

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you can google it up

supple falcon
#

yeah

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wait up

queen stirrup
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hm i dont know but it might help

supple falcon
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i'll try setting both sides equal first

supple falcon
wraith daggerBOT
#

1 divided by 0 equals Infinity

supple falcon
#

distributing the LHS, we get

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$3x^2 + 20xy + 12y^2$

wraith daggerBOT
#

1 divided by 0 equals Infinity

idle tusk
idle tusk
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i'll spare you the misery

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it simplifies

supple falcon
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derivative 😭

idle tusk
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2 x^2 + 3 x y + y^2 + 1

queen stirrup
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did everything but the division

idle tusk
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this

supple falcon
#

...

idle tusk
supple falcon
supple falcon
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$2x^3 + 6y^3 + 15x^2y + 19y^2x + x + 6y = 12$

wraith daggerBOT
#

1 divided by 0 equals Infinity

opal hinge
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,w simplify (2x^3 + 6y^3 + 15x^2 y + 19y^2 x + x + 6y)/(x+6y)

idle tusk
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yup

supple falcon
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thanks lol

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you spared me the factoring

idle tusk
supple falcon
#

anyways it's time to do it

opal hinge
supple falcon
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now ik what to factor

supple falcon
#

defining axioms derived from programming concepts

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types

supple falcon
wraith daggerBOT
#

1 divided by 0 equals Infinity

queen stirrup
#

another hint

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once you get 2x^2 + 3xy + y^2 + 1 = 3x+2y you can transpose and factorise further

opal hinge
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Probably a bunch of square

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Yeah or factor

supple falcon
#

lel

queen stirrup
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damn this question is painful

supple falcon
#

😭

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it's in my homework

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dw

opal hinge
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I had to deal with these things in the past

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That's why i hate algebra

supple falcon
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you a teacher?

opal hinge
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No, I'm a student

supple falcon
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lol

opal hinge
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Just like you

supple falcon
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you from vietnam or smth?

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i remembered who you are if im not mistaken

opal hinge
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Yeah you probably right

supple falcon
#

💀

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am i dividing polynomials just to get a factor 😭

queen stirrup
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not exactly this

queen stirrup
#

like 0 on one side

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and factorisation on the other

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its the natural continuation

supple falcon
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first case: $x + 6y = 0$ or you can't divide by $x + 6y$

wraith daggerBOT
#

1 divided by 0 equals Infinity

queen stirrup
#

o yeah

supple falcon
#

leaving $x = 6y$ easy substitution

wraith daggerBOT
#

1 divided by 0 equals Infinity

supple falcon
#

$x + 6y = 0$ does not satisfy equation (1)

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💀

wraith daggerBOT
#

1 divided by 0 equals Infinity

supple falcon
#

,w factorize 3x^2 + 3xy + y^2 + 1 - 3x - 2y

wraith daggerBOT
supple falcon
#

💀

queen stirrup
supple falcon
#

what's that lmao

queen stirrup
#

,w simplify 2x^2 + 3xy + y^2 + 1 - 3x-2y

supple falcon
#

oh im dead

queen stirrup
#

bruh its so bad

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,w factorise ( 2x^2 + 3xy + y^2 + 1 - 3x-2y)

queen stirrup
#

yeah

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this is the factorisation

supple falcon
#

WHY CAN YOU DO IT WITH AN S

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AND NOT WITH A Z

supple falcon
queen stirrup
#

spelling

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so when you see 2x^2 + 3xy + y^2 + 1 - 3x-2y = 0

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you know its gotta be factored into something like (2x + .... )(x + ,,, )

supple falcon
#

ah yeah

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more like

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$(2x + ... + y)(x + ... + y)$

queen stirrup
#

then you fill as (2x + y + .. )(x + y + ..) to get the 3xy

wraith daggerBOT
#

1 divided by 0 equals Infinity

opal hinge
#

-# Imagin factorizing these things in the test when you only have 15 minutes AlfurStare

queen stirrup
#

then finally (2x+y-1)(x+y-1)

queen stirrup
#

so now we have (2x+y-1)(x+y-1)=0

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so 2x+y=1 or x+y = 1

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i think you can do it

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from here

supple falcon
#

when you snuck a phone to the test

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and use wolfram alpha

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💀

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yeah i have like 45 minutes on my clock

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first case i got $5x^2 + 4x = 0$ 💀

wraith daggerBOT
#

1 divided by 0 equals Infinity

queen stirrup
#

x=0,y=1 works

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then

supple falcon
#

and $x = \frac{-4}{5}, y = \frac{9}{5}$

wraith daggerBOT
#

1 divided by 0 equals Infinity

supple falcon
#

that's for $x + y - 1 = 0$

wraith daggerBOT
#

1 divided by 0 equals Infinity

queen stirrup
#

nice

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any more questions?

supple falcon
#

second case i got $11x^2 - 28x = 0$

wraith daggerBOT
#

1 divided by 0 equals Infinity

supple falcon
#

last one

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$\begin{cases} x^3 - xy^2 - 6y = 0 \ (x + y)(x + 2y) = 3(xy + 2) \end{cases}$

wraith daggerBOT
#

1 divided by 0 equals Infinity

opal hinge
#

People have no chill for doing this type of problem...

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The first eq

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Is quardratic in term y

supple falcon
#

my hw got 3 sections

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all these questions are from section 3

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i got 30 minutes on my clock

honest field
#

try to break down the 2nd equation

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3xy gets eliminated

supple falcon
honest field
#

what do you get?

supple falcon
wraith daggerBOT
#

1 divided by 0 equals Infinity

supple falcon
honest field
#

now replace the 6 into the 1st equation

queen stirrup
supple falcon
supple falcon
supple falcon
wraith daggerBOT
#

1 divided by 0 equals Infinity

honest field
#

expand that

supple falcon
#

$x^3 - xy^2 - x^2y - 2y^3 = 0$

#

in vietnamese

honest field
#

wrong sign

supple falcon
#

phương trình đẳng cấp

wraith daggerBOT
#

1 divided by 0 equals Infinity

supple falcon
#

probably @opal hinge is familiar with that

honest field
#

to make this easy you can divide y^3 on both sides

supple falcon
#

lol

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i think i can do it from hể

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thanks yall

honest field
#

dễ

supple falcon
#

💀

#

decarbonized

#

ik you lol

honest field
#

thì?

supple falcon
#

.close

cedar kilnBOT
#
Channel closed

Closed by @supple falcon

Use .reopen if this was a mistake.

opal hinge
cedar kilnBOT
#

supple falcon
#

i'll keep this channel open until im done lol

queen stirrup
#

so how would you factorise a^3 - a - a^2 -2 = 0

supple falcon
#

you do $a^3 - a - a^2 - 2 = 0$

wraith daggerBOT
#

1 divided by 0 equals Infinity

supple falcon
#

and that's your latex

queen stirrup
#

theres no style points in maths

supple falcon
#

shush

#

not like you would write

opal hinge
supple falcon
#

a^3 - a - a^2 - 2 = 0 in maths

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💀

queen stirrup
#

i use latex for all my projects

supple falcon
#

,w factorise a^3 - a - a^2 - 2

wraith daggerBOT
queen stirrup
#

BRO THATS NOT THE WAY TO FACTORISE

supple falcon
#

lol

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anyways

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i have a problem for yall

indigo lagoon
#

Yeah sure

supple falcon
#

given a polynomial $f(x) = \Sigma_{i=0}^{n}mx^i$ with degree $n$ ($2 \nmid n$) and $m \in \mathbb R, \abs{m} > 0$. Solve for $x \in \mathbb R$

wraith daggerBOT
#

1 divided by 0 equals Infinity

supple falcon
#

@indigo lagoon

queen stirrup
#

wdym solve for x

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so when f(x) = 0

supple falcon
#

yes

queen stirrup
#

or the roots of f(x)?

supple falcon
#

when $f(x) = 0$

wraith daggerBOT
#

1 divided by 0 equals Infinity

honest field
#

isnt this just a geometric progression?

queen stirrup
#

ok m(...)= 0 or (...) = 0. as x is not 1 f(x) = 0 => (x^n+1 - 1)/(x-1) = 0 => x^(n+1) -1 = 0

supple falcon
queen stirrup
#

wait a minute

#

x=1

#

wait

#

sorry

#

x=-1?

supple falcon
queen stirrup
#

n+1 is even

#

so among all the n+1 roots of unity

#

only x = -1,1 are real

#

and 1 doesnt satisfy

honest field
#

also please do not give challenges in help channels

queen stirrup
#

right you should close this

supple falcon
honest field
#

.close

cedar kilnBOT
#
Channel closed

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Use .reopen if this was a mistake.

supple falcon
#

continue in there lol

cedar kilnBOT
#
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calm pine
#

Can anyone reccomend a good channel that helps you understand general topics in math a?

native heath
indigo lagoon
fossil dawn
native heath
#

book recs for videos??

fossil dawn
native heath
#

ah

cedar kilnBOT
#

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fallen coyote
#

for this, would i just plug in numbers close to 3 like 2.999?

fallen coyote
#

i tried this, and got to positive infinity, which is a VA?

native heath
#

yes

fallen coyote
#

.close

cedar kilnBOT
#
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civic sage
cedar kilnBOT
civic sage
#

i have no idea what to do

tough finch
#

have you tried anything yet?

civic sage
#

i could write tan as sin/cos but that leads nowhere

terse kettle
# civic sage

Its very simple...Firstly think how can I convert this sin to tan....Exactly by dividing with cos....So the answer is just divide everything with cos in denominator and numerator....You'll get the answer

native heath
#

have you learnt the ancient art of 'divide by cosine'

upper laurel
#

suppose you try it

#

and find out?

#

for example if you had (5 - 3)/(5 + 3),

#

you can divide by 3/3

last apex
upper laurel
#

and get (5/3 - 1)/(5/3 + 1)

civic sage
last apex
#

its the same thing but in the other directon

#

but what you did is correct

terse kettle
civic sage
#

ok here id prefer working with the RHS

#

.close

cedar kilnBOT
#
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cedar kilnBOT
#
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bronze dome
#

i’m back 😞

cedar kilnBOT
bronze dome
#

idk what i’m doing 💔

modern compass
#

you're 5 line starts at x=0 instead of x=1

#

and there's a closed dot on your -x+8 line at x=6

bronze dome
#

do i open the dot for the 5 line too

modern compass
#

yes, since it's given -5 < x < 1, neither endpoint is included in your line

bronze dome
#

ohh okok

#

does this look correct ? 😭

wooden wagon
bronze dome
#

okay thank you

#

does this look correct ? 😓

final river
bronze dome
#

my bad

final river
bronze dome
#

oh jolly i’m starting to understand this :D

#

.close

cedar kilnBOT
#
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cedar kilnBOT
#
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harsh hazel
#

$P(m,n)=\sum{i=1}^m $

cedar kilnBOT
indigo lagoon
#

remove the space

tropic oxide
indigo lagoon
#

$P(m,n)=\sum{i=1}^m$

wraith daggerBOT
#

This is sad 😢

harsh hazel
#

I need a double summation

tropic oxide
#

$P(m,n)=\sum_{i=1}^m \sum_{j=1}^n (i+j)^7$

wraith daggerBOT
tropic oxide
#

this thing? (from there)

harsh hazel
harsh hazel
neon falcon
#

Oh man I was here for basic math help and one look and I’m cooked

tropic oxide
#

well that's like, what, 9 terms?

#

wait

#

P(3,-3)?

harsh hazel
tropic oxide
#

how are we allowing n to be negative here??

harsh hazel
tropic oxide
#

so P(3,3)?

harsh hazel
tropic oxide
#

i think it is easiest to just write the sum out explicitly ngl

harsh hazel
tropic oxide
#

honestly probably some kind of algebraic magic to reduce this to summations of the form $\sum_{k=1}^n k^p$

wraith daggerBOT
tropic oxide
#

this feels like it's going to end up with like, m^9 type shit

harsh hazel
tropic oxide
#

a natural number

harsh hazel
#

Okay, how can we reach it?

tropic oxide
#

im kinda suspicious tbh of how youve presented the problem

#

can you share a pic of the original

#

like why'd they ask you for the absolute value of sth that is already obviously positive, for example...

harsh hazel
#

@tropic oxide Leave this, this problem is faulty.

#

(3,-3) is simply not defined.

#

Domain of P is Z+

tropic oxide
#

ok no hold on

#

ok so the summation only defines P for m, n in N that's correct

harsh hazel
#

So, we can't use this form for P(3,-3)?

tropic oxide
#

but it is true that it'll be a polynomial in m and n, and that makes sense for any values of the variables

#

so yes we cannot use the summation form directly for P(3, -3)

#

nor do we need to, i think

tropic oxide
#

i think the idea is rather that $P(m,n) - P(m,n-1)$ has a nice expression (which can be used for $n \leq 1$ as well)

wraith daggerBOT
tropic oxide
#

maybe write put P(3, n) and then P(3, n) - P(3, n-1).

harsh hazel
#

Oh alright and then we can plug in n=-3

tropic oxide
#

not quite, you'll need to take it in several steps.

#

you'll need to "roll it back" starting from e.g. P(3, 1)

harsh hazel
#

That's painfully calculative..

tropic oxide
#

is it now

#

can you write me an expression (with one sigma symbol) for P(3, n)?

harsh hazel
wraith daggerBOT
#

L'empereur

tropic oxide
#

good, now the backward difference?

harsh hazel
#

$P(3,n)-P(3,n-1)= (n+1)^7 + (n+2)^7 + (n+3)^7$

wraith daggerBOT
#

L'empereur

harsh hazel
#

So, we have a recurrence relation?

cedar kilnBOT
#

@harsh hazel Has your question been resolved?

#
Channel closed

Closed by @harsh hazel

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#
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Show your work, and if possible, explain where you are stuck.
After 15 minutes, feel free to ping <@&286206848099549185>.
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crimson sedge
cedar kilnBOT
crimson sedge
#

Is this right

last apex
#

you created the graph for this function?

gray roost
#

what

#

is negative 1

crimson sedge
tropic oxide
crimson sedge
last apex
#

there are 3 mistakes

crimson sedge
#

I used desmos

tropic oxide
#

fails the vertical line test for one

gray roost
#

you can put -1 into a function???

crimson sedge
#

bro theres no way

#

wait is desmos

tropic oxide
crimson sedge
#

yea im cooked

#

I put a :

tropic oxide
#

and what did desmos give you

crimson sedge
#

v

#

ah

#

I see

last apex
#

desmos is correct

tropic oxide
#

oh wait hold on

#

you typoed

#

-4x < x < 1?

crimson sedge
#

yes

#

oh

tropic oxide
#

that and you then didn't copy the graph correctly anyway. mind your axes and coordinates

crimson sedge
#

and closed circles

last apex
#

for this you should look at the function it self, and ask yourself what is f(1)

tropic oxide
#

let's focus on the shape first. recreate the graph now, and fill the circles in however you think is right, but don't worry about them

#

we will get the shape right and only then talk about the end circles

crimson sedge
#

now this is

#

better

#

right

tropic oxide
#

yes now it is

#

now look at the horizontal piece, the -1

crimson sedge
#

thats open

tropic oxide
#

its "subdomain" is -4 < x < 1

crimson sedge
#

ah

tropic oxide
crimson sedge
#

so if its greater or less than equal to

#

its closed

#

right

tropic oxide
#

strict inequality (> or <) means open, weak inequality (>= or <=) means closed, yes

crimson sedge
#

ye

tropic oxide
#

that's one of several open circles that will need to be put down.

#

how about you put down all the open circles that you think should be open, and show what you got

crimson sedge
#

1,-1

tropic oxide
#

rather than saying stuff piecemeal like you're doing rn

crimson sedge
tropic oxide
#

far left

crimson sedge
#

so theres

#

3

tropic oxide
#

-4**<**x<1
that end also wants an open circle!

crimson sedge
#

open

#

circle

tropic oxide
#

can

#

you

#

type

#

more

#

than

#

one

#

word

#

per

#

message

crimson sedge
#

so theres 3 open circles

tropic oxide
#

really annoying to read this typing style

tropic oxide
crimson sedge
#

ok

#

thanks

crimson sedge
#

because level one for this is easier

#

and desmos isnt very helpful for the second level

tropic oxide
#

so you have another question like this

#

send it here ig

crimson sedge
#

yes

tropic oxide
#

ok so you have three pieces this time

#

make an attempt

#

then we will see how you did

crimson sedge
#

ok

crimson sedge
tropic oxide
#

i mean, desmos CAN handle functions composed of 3 pieces. (in fact you can put cases in one pair of braces, separated by commas)

crimson sedge
#

I did last time

#

but the graph was wrong

tropic oxide
#

cause you made a typo lmao

crimson sedge
#

ill show you

tropic oxide
#

or like alternatively you could graph these straight line bits manually

#

if you know how to graph y=mx+c it is not terribly difficult in comparison

crimson sedge
#

ok

tropic oxide
#

i would say relying so strongly upon desmos here is a bit silly. it's like learning basic arithmetic in class, and then shoving every single q into a calculator

crimson sedge
#

its a pass or fail class

#

nothing serious

#

I plugged in the third

#

graph

#

and nothing showw

#

s

#

is that a error

#

oh x>0

tropic oxide
crimson sedge
#

highschool

#

precalc

#

im a junior

tropic oxide
#

which is... 11th grade?

crimson sedge
#

yes

tropic oxide
#

are you gonna do anything STEM in uni

crimson sedge
#

never seen this question before

crimson sedge
#

im into science

tropic oxide
#

right

crimson sedge
#

medicine primairly

tropic oxide
#

you'll need math then. suggest taking a less lackadaisical approach to this stuff.

crimson sedge
#

he is 77 years old

tropic oxide
tropic oxide
#

select "closed circle" and click at (5, -3) and then don't click anywhere else

crimson sedge
#

can you demonstrate visually

tropic oxide
#

yes good

#

the other bit of the graph is just the entire line y=2x-7 except for the point at x=5 (on which you should put an open circle)

crimson sedge
#

okay

#

@tropic oxide

#

Like this?

tropic oxide
#
  • make the line go ALL the way across the graph. don't stop it anywhere
  • open circle at x=5 on the line
crimson sedge
#

k

tropic oxide
#

yes, it goes on forever

crimson sedge
#

Like this?

#

@tropic oxide

tropic oxide
#

no

#

that circle should be on the line y=2x-7

cedar kilnBOT
#

@crimson sedge Has your question been resolved?

cedar kilnBOT
#

@crimson sedge Has your question been resolved?

#
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cedar kilnBOT
#
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sonic fossil
cedar kilnBOT
sonic fossil
#

Question is find the velocity of ball and triangular wedge after impact

#

Question is given by teacher in this form so that anyone cannot internet it

#

But I am confused to identify line on impact

#

of*

cedar kilnBOT
#

@sonic fossil Has your question been resolved?

cedar kilnBOT
#
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strong dawn
cedar kilnBOT
strong dawn
#

can anyone help me with question 12 abc

past wave
#

What have you tried?

#

@strong dawn

strong dawn
#

I expressed the equation like this and dont how to go

past wave
#

Nice

#

Do you know how to draw the graph for x²-2x-8?

strong dawn
#

I know how to draw that graph, I just don't how to deal with the u3(x)

past wave
#

Ohk

#

Do you see that for x>3, the output of u3 will be 1

#

So f(x) will just be that quad

strong dawn
#

so I draw a graph of x^2 -2x-8 and erase the part that is less that x = 3

past wave
#

Yup

strong dawn
#

but how about u3(x)=0

past wave
#

Yes for x < 3

lavish linden
strong dawn
#

both graph

past wave
#

Yess

#

Share what you have drawn

strong dawn
#

.close

cedar kilnBOT
#
Channel closed

Closed by @strong dawn

Use .reopen if this was a mistake.

past wave
#

.reopen

cedar kilnBOT
#

past wave
#

@strong dawn

#

The minima is not at x=3

#

Oh shi mb

#

It's correct

#

.close

cedar kilnBOT
#
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cedar kilnBOT
#
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orchid salmon
#

hi

cedar kilnBOT
opal hinge
#

wassup

orchid salmon
#

are u australian

opal hinge
orchid salmon
#

ok no prob

#

i got like the big test for year 11 coming up

#

so like

#

early entry for uni test or wtv in otgher countrys

#

coutnies

#

im not bothered to spell sorry

#

i dont understand how to get something else to a subjectof the formula

#

its so confusing

#

this from my study queystions

#

my teacher gave

woven ruin
#

which one of these do you not understand

orchid salmon
#

making r the subjeect of the formula

woven ruin
#

the context of a rope is basically irrelevant in this case

woven ruin
#

instead of T = something

orchid salmon
#

r = 1 ig

woven ruin
#

R is a variable

#

move R to the left side

#

and everything else to the right side

#

by squaring, dividing and multiplying

orchid salmon
#

so first ik u square both sides yes?

woven ruin
#

yes

orchid salmon
#

ok

#

now divide

#

divide what 😭

woven ruin
orchid salmon
#

oksy

woven ruin
#

what do you have after squaring

orchid salmon
#

T^2 = 8R over 2.5

woven ruin
#

okay what will you do next

orchid salmon
#

i have no idea

woven ruin
#

what would you have if you multiplied both sides by 2.5

orchid salmon
#

T^2 = 20 R

#

wait

woven ruin
#

think harder

orchid salmon
#

oh

#

the 2.5 will move to other side

#

and since it sa fraction

#

the other will disappeasr

woven ruin
#

indeed will

#

so what will you end up with

orchid salmon
#

so T^2 x 2.5 = R

woven ruin
#

you dropped a number

orchid salmon
#

8

#

20

#

SHJIT

#

8 R

#

not 20

#

T^2 x 2.5 = 8 R

woven ruin
#

yes

#

and what’s the last step left to do so that you only have R = …

orchid salmon
#

divide both sidr by 8?

woven ruin
#

yes

orchid salmon
#

actually

#

i just guiessed

woven ruin
#

well

orchid salmon
#

l;olk

woven ruin
#

so part a done

#

is part b clear

orchid salmon
#

lemme read it rq

#

b What is the length of rope if it takes 16 seconds for a single revolution?

#

i measn its just putting it in to the formula u just helped me get

#

OLH MY GOD

#

IT ACTUALLY WORKED

#

80

#

YES

#

c What is the time taken for a rope of length 18 metres to complete a revolution? Answer correct to
one decimal place.

#

ok

#

YES

#

i got them right now

#

thanks

#

i might have more questions in a bit when i do other quesitons

woven ruin
#

ye feel free to ping me

#

for now close this channel

cedar kilnBOT
#

@orchid salmon Has your question been resolved?

cedar kilnBOT
#
Channel closed

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

Hey guys can anyone explain me my doubt

nocturne yacht
#

It's more physics than maths but still

indigo lagoon
#

Yeah, just post

nocturne yacht
#

You know that equation f=ma

#

Which earlier is f (directly proportional to )ma

#

So we add that k and make it f=kma

#

And then we say that let f,m&a be 1 so k will be 1 too

floral arrow
#

It only depends on the units you use

sonic fossil
nocturne yacht
sonic fossil
#

What is logic of saying f is directly proportional to ma

nocturne yacht
#

I don't know if it's directly proportional but this is the sign

#

Sorry the image changed

sonic fossil
#

Yes it is sign of directly proportional

livid hound
#

$\propto$

wraith daggerBOT
#

ραμOmeganato5

nocturne yacht
#

So then it's correct

floral arrow
#

Yes it is

livid hound
#

F = ma = kma with k=1

nocturne yacht
#

We take k as the constant of proportionality

#

See that's in my book

sonic fossil
#

if there is acceleration then this is due to force.
=> $$ F $\propto$ a
=> F = ma where F is net force on the object and m is mass of com and a is acceleration of com

wraith daggerBOT
#

BlackidoZΣ
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

sonic fossil
#

Ahh my latex

nocturne yacht
#

Yeah but my question is not that

floral arrow
#

The force F is defined such that k = 1

sonic fossil
#

alr

floral arrow
#

That's what your book says

nocturne yacht
#

I wanna know when we take f,m&a 1 the k them to 1 so what if we all of that 2

sonic fossil
#

It's defined there with different way

sonic fossil
nocturne yacht
# sonic fossil Can you rephrase your wording please

Ah sure
We know that after we got f=kma , we take / suppose value of f , m & a to be 1N , 1kg & 1m/s² respectively and obtain k = 1 and then we write f=ma .
But what if i take all those 2 (/ or any other constant) wouldn't that make the value of k different

#

Like in the case of 2 ,k will be 1/2

sonic fossil
#

It would make a difference if you change magnitude but here we take k = 1 to balance the proportionality sign

floral arrow
#

What you don't seem to understand is that 1 Newton is defined to be 1kg * 1m/s²

floral arrow
#

If you take 2kg and 2m/s², then F = ma because F = 4N

nocturne yacht
sonic fossil
floral arrow
#

You can define your own unit if you want, say a T, where 1T = 2N
Then you can have 2T = 2kg * 2m/s²

nocturne yacht
nocturne yacht
#

Sorry guys if i am wasting your time but i just can't get my head over it

floral arrow
#

k = 2

#

The point of a Newton is that k = 1

nocturne yacht
nocturne yacht
floral arrow
#

Because we define it that way

nocturne yacht
floral arrow
#

Convenience

nocturne yacht
nocturne yacht
sonic fossil
# nocturne yacht Can you explain more briefly

For different situations in physics you deal with different forces and as far as putting different magnitudes for m and a you will get a force on that body with it's acceleration, here the value of k is equal 1,the reason is that if you take a mathematical constant to be any value( as you're saying 2,3,4etc) then 1)it won't give you the exact force acting on particle. 2) if you multiply k to m and a force then will be a multiple of that constant, in short force will be different from its original calculation.

floral arrow
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... from the definition?? I don't understand what you don't understand about this

sonic fossil
nocturne yacht
floral arrow
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We already use kg for mass and m/s² for acceleration, these are our standard units

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Since force is the product of these two, we use the unit kg*m/s², and we call it N

nocturne yacht
floral arrow
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Rather, since force is proportional to the product of mass and acceleration, we use the unit kg*m/s², instead of 2kg*m/s² or something else

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Because we don't want to keep a useless constant around

sonic fossil
sonic fossil
nocturne yacht
floral arrow
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Sorry, if you can't understand that we define things such that they are convenient to use, I can't help you further

nocturne yacht
nocturne yacht
sonic fossil
# nocturne yacht Why

It's good to ask why but not for the fundamental definition, physicists observed nature and then wrote it in mathematical terms and so definition is fundamental

nocturne yacht
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Ok sorry but i just wanted to understand it

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Sorry again for wasting your time @sonic fossil

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.close

cedar kilnBOT
#
Channel closed

Closed by @nocturne yacht

Use .reopen if this was a mistake.

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glacial warren
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Hey i need help understanding logs, im in calc 2 but my teacher says they are review from calc 1(but my teacher in calc one barely touched them)

indigo lagoon
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What sort of log

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Like from the basics?

glacial warren
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yes

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natural logs and regular logs

indigo lagoon
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Alright, do you have any prior knowledge about it?

glacial warren
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very little

indigo lagoon
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It's okay, just tell evrythung you know about log

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everything

glacial warren
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so

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i know that log base 2 (8) = 3

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so its like 2^3 is 8

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but then they started to put xLn(x) / x and asked to take the deriv

indigo lagoon
wraith daggerBOT
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This is sad 😢

native heath
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lmao

indigo lagoon
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oops

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@native heath can you fix it 4 me?

native heath
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this is hideous latex

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$\log_2(8) = 3$

wraith daggerBOT
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Περσυ

glacial warren
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yes that^

indigo lagoon
native heath
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see @indigo lagoon the helpee knows better than you

glacial warren
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not really

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my calc one teacher didnt touch more than that

indigo lagoon
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Alright

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Let's talk about how to add two 🪵

glacial warren
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sorry if im kinda a lost cause

indigo lagoon
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So basically $\log_{a} b + \log_{a} c = \log_{a}{bc}$

wraith daggerBOT
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This is sad 😢

indigo lagoon
indigo lagoon
glacial warren
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okay so if it was log base 2 of 8 and log base 2 of 4 it would become log base 2 of 32

indigo lagoon
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yup

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exactly

indigo lagoon
glacial warren
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so 2^5

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so it would be log base 2 of 32 = 5

indigo lagoon
glacial warren
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okay cool!

glacial warren
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so i can kinda understand natural logs

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its just another way of exponents

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but what exactly are natural logs

indigo lagoon
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it's just log with base e

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nothing special

glacial warren
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what is e exactly ...

indigo lagoon
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,w e

wraith daggerBOT
glacial warren
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sorry if thats a dumb question

indigo lagoon
glacial warren
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anyone you recommend?

indigo lagoon
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overall, e is a irrational constant

indigo lagoon
glacial warren
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okay will do! also i really appreciate the help

native heath
indigo lagoon
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Anything else? We've only undergone one property

glacial warren
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i was gonna show you the math problems ive been attempting

indigo lagoon
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Sure!!

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More than welcome

indigo lagoon