#help-10

1 messages · Page 482 of 1

frozen willow
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Thanks very much

twilit loom
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np ^^

frozen willow
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.close

obtuse pebbleBOT
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west warren
#

Hi, what do we call this in english ? ($f(x)=x^2
f'(x)=2x$)

warm shaleBOT
west warren
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i study math in arabic & french lmaoo

quaint glen
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f'(x) is called the derivative of f(x)

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is that what you wanted?

west warren
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tysm

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.close();

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.close

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timid silo
obtuse pebbleBOT
timid silo
#

tried it twice, couldn’t get the answer

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solution is 9/2

timid silo
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to the tangent

short spruce
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derivative is incorrect

timid silo
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nvm, got it

short spruce
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alright

timid silo
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wait what

short spruce
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lol

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you got it with the wrong derivative?

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wait i can’t read nevermind

upbeat island
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m = 5 - 1/2sqrt(1) is correct

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you subtracted incorrectly

timid silo
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i just realised that 5-(1/2sqrt1) gives 9/2

timid silo
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just looked over it and noticed

short spruce
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yeah don’t have my glasses on i’m smart 👍

timid silo
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hahaha it’s no problem cheers for the help 👍

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attempted this a few times and got the same answer

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the answer is 5/64🤷🏻‍♀️

upbeat island
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first term of derivative should be -3/2 x^{-5/2}

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exponent -3/2 - 1 = -5/2

timid silo
upbeat island
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when you compute the derivative
very bottom left

timid silo
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oh yeah that’s right.

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also this too.

upbeat island
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you plugged in positive two

timid silo
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i did?

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oh.

obtuse pebbleBOT
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@timid silo Has your question been resolved?

obtuse pebbleBOT
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obtuse pebbleBOT
#
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uneven scaffold
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how to solve this question

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and this one

upbeat island
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in the first question, the triangle is drawn a little misleadingly, i would start with annotating everything they give you and see what it forces as an outcome (don't trust how it's drawn)

for the second i would start with cubing both sides of the given equation

obtuse pebbleBOT
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idle condor
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how would I go about solving this question?

obtuse pebbleBOT
soft sail
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Are you familiar with the fact that the collection of (x,y) pairs in the plane satisfying each equation defines a line?

idle condor
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I'm not sure what that means

soft sail
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Have you worked with equations of the form y=ax+b?

idle condor
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yes of course

soft sail
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The define a line in the plane yes?

idle condor
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yeah makes sense now

soft sail
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Would you agree that each equation in the problem you gave defines a line then? Since you can rearrange the terms to make them look like "y=ax+b"?

idle condor
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yes

soft sail
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So, solving the systems of equations stands for finding the points at which the 2 lines ( 2 equations ) intersect, agree?

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Since each equations defines a line so if I have an intersection that point "satisfies" both

idle condor
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yeah

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I can't solve for m though

soft sail
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With all that in mind, what do you think is going on geometrically when the system has no solutions?

soft sail
idle condor
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the lines are parallel when there are no solutions right

soft sail
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Bingo-ish

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2 lines being parallel stands for the a in y=ax+b being equal right?

idle condor
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yes

soft sail
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If we have 2 lines with equal a but different b then they never intersect

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If the B's are equal they intersect everywhere since the equation is the same

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That's the infinitely many solutions part of it

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So if you reduce both equations to y=ax+b with equal a and different B's it solves the no solution case, if the B's are qual it solves the infinitely many case

idle condor
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yeah

soft sail
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Can you make each equation look like y=ax+b?

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The first one is $y=\frac{8}{2}-\frac{m}{2}x$

warm shaleBOT
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Brun。

soft sail
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Can you do the second?

idle condor
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yeah I got that one

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y = (-2m -4x)/(2-m)

soft sail
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You got the signs wrong

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On the 4x

idle condor
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meant to type y = -(2m -4x)/(2-m)

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anyways the gradient is 4/(2-m) right

soft sail
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Yup, and you want that to be equal to -m/2

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For them to be parallel

idle condor
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m is -4 or 2

soft sail
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There's a problem at 2 tho

idle condor
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oh yeah

soft sail
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We've got ourselves a nasty division by 0 since we rearranged

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But looking back at the original equation you see that m=2 just makes the y term vanish

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That means we have a vertical line at x=1

idle condor
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so it has to be -4 for there to be no solutions

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and -2m/(2-m) needs to equal 4

soft sail
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Well, let's see what happens to the constant term

soft sail
idle condor
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which m = -4 satisfies

soft sail
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It doesn't

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8/6

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Different constants => no solutions

idle condor
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oh so it is correct

soft sail
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And that's it

idle condor
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so for infinitely many solutions the two lines need to be the same right?

soft sail
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Yeah, same a and same b

idle condor
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is that even possible?

soft sail
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Not in this one

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No value of m makes that happen here

idle condor
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doesn't 4?

soft sail
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One will be 4 and the other will be -2

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The slopes

idle condor
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you sure?

soft sail
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You can verify it on desmos, it's a great way to catch errors lol, I apologize if I've made any mistakes but I think I am right on that

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Write the 2 equations there and let m=4 to see if they don't intersect

idle condor
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4 does work

soft sail
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Wdym by work tho? Let's clear that up first

idle condor
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the two lines are the same when m = 4

soft sail
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Huh, that's a thinker

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I'd go back and redo the quadratic from before

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Maybe there's something there?

soft sail
idle condor
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I think I was wrong before it should be m = 4 or -2

soft sail
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Oh nice

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And -2 doesn't make the B's equal, so that's the no solution one

idle condor
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it makes sense then

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so what does the last questions even mean to solve the equation in terms of m for suitable values of m?

soft sail
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m that doesn't satisfy the quadratic

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you want the lines to not be parallel

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To have a meaningful unique solution

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If it lets you chose an m to work with I'd go for a 2 to get rid of the y in the second equation

idle condor
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the solution to part b is

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I don't really understand how this works

soft sail
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You will have to sub-in the y given by the first equation into the other

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That forces it to satisfy both "rules" at once

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Then you just isolate for x and you should get the expression in the answer there

idle condor
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did I do something wrong I'm not sure?

obtuse pebbleBOT
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@idle condor Has your question been resolved?

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hybrid moat
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can someone explain me what is linear map ?

obtuse pebbleBOT
hybrid moat
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in simple worlds

sage geode
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Linear map is a mapping satisfying the following two properties:
$f(u + v) = f(u) + f(v)$ and $f(c\cdot{v}) = c\cdot{f(v)}$, also $f(0) = 0$

warm shaleBOT
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Touch Our Beans

sage geode
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Shortly, a mapping which preserves addition and multiplication

hybrid moat
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mapping is like a function?

sage geode
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Yeah

hybrid moat
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so it is a function

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so what the diffrence betweein functions and linear map ?

sage geode
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Function represents mapping between two sets (domain and codomain)

hybrid moat
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and linear mapping?

sage geode
hybrid moat
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and transformation matrix ?

sage geode
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Linear mappings are represented with corresponding matrices

hybrid moat
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and are there other ways to represnt linear mappings?

sage geode
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For example in real functions we have an identity function f(x) = x (it leaves the input unchanged), and in linear algebra there's an identity matrix (which similarly leaves the input unchanged)

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For example this is the identity matrix in 2 dimensions

hybrid moat
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what is identidy matrix

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why is it so confusing

sage geode
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A matrix which leaves the vector unchanged

junior inlet
sage geode
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So $\mathbb{I}\cdot{v} = v$

sage geode
warm shaleBOT
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Touch Our Beans

sage geode
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Where I is the identity matrix and v is an arbitrary vector

junior inlet
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same with v * I

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it's also v

junior inlet
warm shaleBOT
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just bob

sage geode
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Yes I already told him that

junior inlet
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oh ok

hybrid moat
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but how can i represent it in

junior inlet
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didn't notice that

hybrid moat
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matrics

hybrid moat
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i want to do it with matrics

sage geode
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Then view that as $f(v) = A\cdot{v}$ for some matric A

warm shaleBOT
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Touch Our Beans

junior inlet
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if you want a function with 1 variable, don't use matrices

junior inlet
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(redundant also)

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but whatever

hybrid moat
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i will upload something

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what is the meaning of what is written

sage geode
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There's a lot of different things going on there, which part interests you?

junior inlet
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which isn't shown in the picture

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so i have no clue what this means

sage geode
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For example in first lines there's a matrix $T: \mathbb{R}^3 \rightarrow \mathbb{R}^3$ and the writer is trying to find the unknown vector given in the equation, I suppose

warm shaleBOT
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Touch Our Beans

hybrid moat
sage geode
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This is something about using different basis in the vector space, can't tell in details

hybrid moat
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thats true

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thats what he told

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something about changing basis

junior inlet
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that's the matrix, right?

hybrid moat
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but what does it even mean

sage geode
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Every nxn (n by n dimensions) matrix has n^2 entries (numbers) in it

hybrid moat
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and something about ker

junior inlet
sage geode
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Ker stands for kernel of a matrix

hybrid moat
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kernel of linear map

sage geode
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In terms of linear transformations, kernel is always just a set with the zero vector

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As far as I'm concerned

hybrid moat
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wait so it is the same

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about linear transformation and matrix ?

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the kernel

junior inlet
sage geode
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Linear transformations are matrices, in some sense

hybrid moat
sage geode
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L is a linear transformation applied to some vector v

hybrid moat
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and v belong to v

sage geode
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Capital V is some vector space

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(set of all vectors)

hybrid moat
hybrid moat
sage geode
hybrid moat
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L(v) it means to multiply with some vector in order to get 0 vector

sage geode
hybrid moat
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matrix which is L

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right ? ?

sage geode
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Yes

hybrid moat
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is there a diffrence between nullspace and ker ?

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i think i started got it

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a little

sage geode
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"Kernel is also known as the nullspace"

hybrid moat
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so it is the same thing

sage geode
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Yes

hybrid moat
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linear operator

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is te same ?

sage geode
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Linear operator is the same as what?

junior inlet
hybrid moat
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why is my teacher told me that ker=nullspace only in this case

hybrid moat
# sage geode

and he told me that L(v) is not multiplication it is like a function it can be multiplaytion but also addition

junior inlet
hybrid moat
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how much time will it take me to learn it

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is it possible to master it in 2-3 days from the begining and know how to solve problems ?

junior inlet
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personally it took me 1 month at 10 hours of math / day

hybrid moat
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wow, why so much time

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thats pretty a lot of time

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is there a lot which I still dont know ? ? ?

junior inlet
hybrid moat
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Inner product space
is the last subject of mine

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eigenvalue

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Eigenvalues and eigenvectors

junior inlet
junior inlet
hybrid moat
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are you kidding ?

sage geode
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For every matrix there are some vector(-s) such that $A\cdot{v} = \lambda\cdot{v}$

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where lambda is some scalar

warm shaleBOT
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Touch Our Beans

sage geode
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The solutions to that equation are eigenvectors

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And values of lambda are corresponding eigenvalues

hybrid moat
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wat is eigenvalues?

junior inlet
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basically

v is the eigenvector
A is your matrix
lambda is the eigenvalue

sage geode
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Imagine solving equation f(x) = kx, where k is some constant, this is similar thing

junior inlet
hybrid moat
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beans's thing?

junior inlet
hybrid moat
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what about dimension of matrix

sage geode
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For nxn matrix there are n eigenvectors/eigenvalues

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(sometimes eigenvalues are repeated)

hybrid moat
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(1 1)

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dimension 2?

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thats not about 3D ?

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LIKE MOVIES 3D 2D GAMES ?

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THERE IS NOT RELATION BETWEEN THE TWO ?

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??

sage geode
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What do you mean

hybrid moat
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how do i know the dimension

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if i have matrix 2x3

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is it just doing multiplaction for knowing the dimension?

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2*3=6

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thats the dimension??

sage geode
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You just write the dimension as 2x3 (2 by 3)

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I think

hybrid moat
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i mean is there a diffrence between dimension of matrix and dimension of vector spaace?

junior inlet
hybrid moat
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and dimenson of matrix

hybrid moat
obtuse pebbleBOT
#

@hybrid moat Has your question been resolved?

obtuse pebbleBOT
#

@hybrid moat Has your question been resolved?

obtuse pebbleBOT
#
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steady bay
#

Hey guys,
I have this function, a solution to a differential equation
I1 = ]-inf; 0[
I2 = ]0; +inf[

steady bay
#

mb not finished

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We want to even find the solution when t=0

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So we find the limit when t --> 0

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The problem is I don't understand how they got to the limit exists if C1=C2=-1

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I used l'hopitals rule and I got the limit equals 0 no matter what constant we use

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So thats wrong

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Can someone help me with determining C1 and C2?

obtuse pebbleBOT
#

@steady bay Has your question been resolved?

steady bay
#

oh sorry

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<@&286206848099549185>

obtuse pebbleBOT
#

@steady bay Has your question been resolved?

obtuse pebbleBOT
#

@steady bay Has your question been resolved?

steady bay
#

No

slim leaf
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@steady bay For the limit to exist, we need the right hand limit to equal the left hand limit. So that's what they did.

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The right hand limit is lim t-->0^+ [(c2(t^2 +1) + 1)/t], left hand limit is lim t-->0^- [(c1(t^2 +1) + 1)/t]

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since t-->0^- in the left hand limit, we have lim t--> 0^- [-(c1(t^2 +1) + 1) / |t|]

slim leaf
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since t-->0^+ in the right hand limit, we have lim t-->0^+ [(c2(t^2 +1) + 1) / |t|]

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equating these, terms cancel out

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you get c1+c2 = -2

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if u dont understand the absolute value stuff, then there is another way. lim t-->0^- means t approaches 0 from the left so it's gonna be a smaller and smaller negative number

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you take the negative sign out, send it to the numerator

slim leaf
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and what u have left is a positive number

steady bay
slim leaf
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thats why i wrote |t|

steady bay
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But how do we know that the limit exist to begin with

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What I dont understand is that if I try to get the limit with whatever C i get 0

slim leaf
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the limit is 0 yes

steady bay
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Did you get it using lhopitals rule?

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Because i get it like that and on top if t goes to 0 it doesnt matter the coefficient so even if c1 is different than C2 we get the same limit.

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Thats why i dont know what i did wrong

slim leaf
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lets take c1 = 5

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so you have lim t-->0^- [(-5(t^2 + 1) +1)/t]

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and this limit doesn't exist

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,w limit of [(-5(t^2 + 1) + 1)/t] as t goes to 0 from left

slim leaf
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same for lim t-->0^+

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so if we want the limit to exist

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we want it to have the form 0/0 or inf/inf to apply LHR

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what u are doing is just applying LHR(not thinking whether it even is of the form 0/0 or not)

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so u get the first equation c1 + c2 = -2 by equating left and right hand limits

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For second equation, we see that the limit is of the form (constant/0) which means the limit doesn't exist, so for it to exist, we must have the form 0/0 so that we may apply LHR

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so applying lim t--> 0 to the numerator of either limit, you get c1 + 1 or c2 + 1 which must equal 0 so we have c1 or c2 = -1

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and then from the first equation, we find the value of the other constant

steady bay
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Okay I see that makes sense

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Thank you very much

slim leaf
#

np

#

Close the channel if u are done, or ask any more questions that u may have.

#

🙂

obtuse pebbleBOT
#
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storm wagon
#

sinx+1/√3cosx=1
What is the smallest positive value of x?

storm wagon
#

I find sin(30+x)=2/√3 and this looks so strange, and I don't know what to do next.

sage geode
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$\sin(30 + x) = \frac{2}{\sqrt{3}} \iff 30 + x = (-1)^k\arcsin(\frac{2}{\sqrt3}) + \pi{k}$ for some whole number $k$

warm shaleBOT
#

Touch Our Beans

storm wagon
sage geode
#

Oh

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Then you need to find some value of k

sage geode
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Here I'd consider cases k being odd/even and looking for lowest positive values of x in both of the cases

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And then compare the results

storm wagon
#

.close

obtuse pebbleBOT
#
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candid orchid
#

Can someone help with these here?

obtuse pebbleBOT
candid orchid
#

B especially

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is there an identity I'm missing?

formal atlas
#

Take tangent of both sides, use the fact that $\tan(a+b)=\frac{\tan(a)+\tan(b)}{1-\tan(a)\cdot\tan(b)}$

warm shaleBOT
dapper geode
#

try using tan(a+b)

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oh

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do arctan(p) = a and arctan(q) = b

obtuse pebbleBOT
#

@candid orchid Has your question been resolved?

candid orchid
obtuse pebbleBOT
#
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candid orchid
#

thank you both!!

obtuse pebbleBOT
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neon grove
#

What is the probability of a 2% event occurring 4 times out of 10?

next violet
#

any arrangement of this occuring will have the same probability

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so the first step is to find how many arrangements are possible

spiral maple
neon grove
#

question just came out of the blue, i just high-rolled on a game

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don't know the difference :^)

spiral maple
#

So.... I asked a yes or no

neon grove
spiral maple
#

If you had the event happen, will that affect the next time it happens?

neon grove
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no

spiral maple
#

So yes, they're independent

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Anyway you can model it w/ a Binomial distribution

neon grove
#

Don't really know how to do that :^)

spiral maple
#

$X\sim Bin(n,p)\implies P(X=x)=\binom{n}{x}p^x(1-p)^{n-x}$

warm shaleBOT
neon grove
#

wat

spiral maple
#

That's binomial distribution..

neon grove
#

don't know how to use that :^)

spiral maple
#

n=10, p=0.02...

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x=4..

neon grove
#

what does the squiggly mean

spiral maple
#

Follows.

neon grove
#

and that means?

spiral maple
#

and tilde

#

X the random variable follows a binomial distribution w/ parameters n and p.

dull forge
#

At least this will give you a really fun starter and if you have any specific questions there, it might be more helpfull to come here. Mosh probably tries his best explaining this topic to you, but since it could take a while i thought this might help.
Also some games are programmed so that the results of each attack (or whatever) aren't independent. But that's probably not helping you with your question.

neon grove
#

I do know that some games are programmed to not be independent, but would like to know the answer if it were independent.

dull forge
#

Then the buzzword Mosh gave you with this video should help you a lot! I think its great that you are trying to get into math with real world problems you encounter 🙂

neon grove
#

I have no clue what the big x and the small x in that equation means

dull forge
#

Did you try wathcing that video? It might be hard to explain this whole topic of binomial distributions in an easy to understand and short way here 🙂

neon grove
#

don't really understand what this means / how i'm supposed to use it

dull forge
#

do you know what the ! stands for?

neon grove
#

factorial idk

dull forge
#

yep!

#

Do you know what that is?

neon grove
#

n x n-1 x n-2...

dull forge
#

until n-whatever reaches 1. Correct 🙂

#

Oh you were asking what the n and x stand for right?

neon grove
#

yeah, it's not something I've ever seen

#

don't know how to use it

dull forge
#

Well its called "n over k" (at least i think it is. english isnt my first language)
To calculate it, you use the formula above. But what do you think the n and k could mean?

neon grove
#

the guy in the video says choose

#

n over k is like n/k

#

I don't really know how it can be used or what it would mean

dull forge
#

btw its the same video just with a timestamp

#

Oh and just as a small motivation:
At the end of this you will be able to solve lots of problems you will encounter in games! You could basically calculate if some builds or bossraids are worth your time 😉

neon grove
#

yeah, that'd be cool

#

out of 10 tries, I got 4 high-rarity drops

dull forge
#

perfect thats n over k!

neon grove
#

i don't really know where to go from here even after watching the videfo

#

can i get a really rudimentary explanation as to what I would do with knowing n over k?

dull forge
#

what did you get out of the video is this

$$p^x(1-p)^{n-x}$$
warm shaleBOT
dull forge
#

i mean you got the n over k part down, now you are just missing this thing from the equation right? A little hint: It's in about the same timestamp i send you earlier.

neon grove
#

no no

#

i don't know how to apply

#

n over k

#

I know how to plug everything in

#

but I don't know how to use n over k

dull forge
neon grove
#

oh i kinda like

#

didnt look at that very closely lOL

#

(210) x (0.02)^4 x (1-0.02)^6

dull forge
#

looks about right

neon grove
#

so approximately a 0.003% chance?

dull forge
#

i got 0.0003%
But i (probably) used the same numbers.

neon grove
#

oh am i not supposed to multiply by 100 to turn it into a percent?

dull forge
#

oh and i guess its worth mentioning that many calculators use 10 nCr 4 as 10 over 4

neon grove
#

oh really?

#

that's helpful

dull forge
#

I had to look it up, since it was a while ago i used it. So sorry for only telling you now

neon grove
#

thanks for the help

dull forge
#

I hope that helped you!

neon grove
#

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minor warren
#

hey so according to the right hand rule should the magnetic force be pointing upwards or downwards in this problem?

I've gotten the magnetic force to be pointing ||upwards|| but it is ||downwards|| in the book

minor warren
#

<@&286206848099549185>

obtuse pebbleBOT
#

@minor warren Has your question been resolved?

minor warren
#

okay got a solution for my answer
it is pointing downwards cuz the charge is negative and the right hand rule is supposed to be used for positive charges

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latent canyon
#

well i thought it was the 5000 1000p vector + t(2.5cos70 2.5cos20) but ms says this

quaint glen
#

your answer is manjit's position vector

#

you want raj's position vector

latent canyon
#

Ohhh

#

How do we do that then?

#

I'm guessing you gind the velocity from the 2m/s speed?

quaint glen
#

yes. His speed and the bearing he's travelling at.

latent canyon
#

So the speed is the hypotenuse in this case?

quaint glen
#

yuh

latent canyon
#

This right.

#

?

#

Angle 40 not 20

#

Oh yes I see now

#

Tysm

#

.close

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novel inlet
#

Ha car accelerates from 0 km/h to 100km/hr in 2.5 seconds. if the acceleration is uniform how much does it accelerate in 1 second

sage geode
#

a = (v1 - v0)/deltaT

novel inlet
#

Can yiu tell answer i can't understand what yiu gave

sage geode
#

And convert the km/hr to m/sec

sage geode
novel inlet
#

Did

#

0 m - 10,000 m

high lily
#

wheres 10000m coming from

cedar flicker
#

change km/h to m/s not just km to m

novel inlet
#

Ohh

royal basin
#

do we need to do any unit conversions here though

novel inlet
#

27.7778/s

royal basin
#

ew decimals

novel inlet
#

Lol

royal basin
#

(also missing units? idk)

#

we aren't asked to find the acceleration, we're asked to find by what amount we accelerate in one second

#

and answering "the car speeds up by ___ km/h" is perfectly fine

novel inlet
#

My brain is dead

royal basin
#

okay then maybe you could revive it and come back here once it's back up and running?

novel inlet
#

No no its running

cedar flicker
#

(final velocity-initial velocity)/time is the formula

#

for acceleration

#

plug in the numbers

sage geode
novel inlet
#

My brain not undertaking formula

cedar flicker
#

what is final velocity of the car

royal basin
#

as-stated, giving an answer in (km/h)/s is perfectly fine

sage geode
#

You weren't given the formula before this problem?

royal basin
#

UNLESS we are also required to convert it into m/s^2, of which OP has made no indication

novel inlet
#

Isnt thia formula

cedar flicker
#

yes

#

can you tell me the final velocity of the car

novel inlet
#

I just need answer idk whrre the mam gave this question from

#

Tbis is the question the q:2

cedar flicker
#

well you did the q1 wrong

#

but nevermind that can you just tell me the last speed of the car

novel inlet
#

100km/h

cedar flicker
#

YES

#

what was its first speed

novel inlet
#

Qhat the q1 is wrong

#

0

cedar flicker
#

yes

#

so what is final speed-initial speed

novel inlet
#

I used my brain in q:1

#

What final initial speed idl you can see the question

cedar flicker
#

final speed is last speed

#

initial is first

#

you just said 100 and 0

#

so what is the difference

novel inlet
#

100 is difference

cedar flicker
#

yes

#

it goes from 0 to 100 in 2.5 seconds

novel inlet
#

Yes

cedar flicker
#

so how much will it go in 1 second

novel inlet
#

Idk thats shy i am here

#

Wait i will divide by 2.5 i think

cedar flicker
#

yea good idea

novel inlet
#

Time to find my calculator

cedar flicker
#

you can just

novel inlet
#

40

cedar flicker
#

okay

novel inlet
#

100÷2.5=40

#

So is 40 answer

#

And also what i did wrong in q:1

cedar flicker
#

you figure that out

#

I believe in you

novel inlet
#

I can't my brain dead

#

I gave my brain power to you remember our contract

cedar flicker
#

if there is no force acting on it

#

it will fly

novel inlet
#

An object with no net forces acting on it which is initially at rest will remain at rest. If it is moving, it will continue to move in a straight line with constant velocity. Forces are "pushes" or "pulls" on the object, and forces, like velocity and acceleration are vector quantities.

#

Got from google

cedar flicker
#

yea if it is initially at rest

novel inlet
#

Ohhhhh

cedar flicker
#

otherwise it will fly like a bird you should write that down

novel inlet
#

Big brain

#

Lol

cedar flicker
#

im serious

novel inlet
#

Ok

cedar flicker
#

like it will keep going up and down

#

it makes sense right?

novel inlet
#

Ohk

#

Yea

#

.close

obtuse pebbleBOT
#
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cedar flicker
#

and if you dont touch it

#

it will turn into a black hole

novel inlet
#

Ir

#

It will rain money $$$$

cedar flicker
#

so when you see an object going up and down you should touch it

novel inlet
#

$_$

cedar flicker
#

in real life too

warm shaleBOT
#

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

cedar flicker
#

its important

obtuse pebbleBOT
#
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obtuse pebbleBOT
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brisk arrow
#

how i write the symbol theta

obtuse pebbleBOT
twilit loom
#

$\theta$?

warm shaleBOT
#

dino dik

royal basin
#

do you mean write on a computer or on paper?

brisk arrow
#

paper

#

does it look like theta

royal basin
#

yes

brisk arrow
#

which is better

royal basin
#

the one on the right looks better

brisk arrow
#

becuz the line on the middle of the circle? it should be horizontal right

high lily
#

slightly curved is fine

ruby ravine
#

yeah, simply make a zero, and put a line across it

high lily
#

I start from the mid left
draw the horizontal line
and continue with the ellipse, anticlockwise

#

(without the writing implement leaving the page)

ruby ravine
#

but a lot of people wont mind how you write the symbol, just make sure it resembles theta

royal basin
high lily
#

I never had that issue

obtuse pebbleBOT
#

@brisk arrow Has your question been resolved?

obtuse pebbleBOT
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trail vector
#

Hello! I’m having a lot of trouble proceeding with this exercise, I don’t know how to get off from here. Can someone give me a hint ? Thanks !

obtuse pebbleBOT
#

@trail vector Has your question been resolved?

obtuse pebbleBOT
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leaden vortex
#

Can anyone see how i can go from the bottom line in my equation to the below equation

leaden vortex
#

to this

obtuse pebbleBOT
#

@leaden vortex Has your question been resolved?

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brazen glen
#

hello i have a question please on this drawing i need to find the possibilities/numbers of rhombus to create a star and the angles need to be between 10° and 160°. To find the possibilities do i need to take the numbers divisible by 360 and that are between 10 and 160 like 20 ? thx

brazen glen
#

❤️

#

thank you very much

#

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torpid lintel
#

Prove that for any real numbers a, b, c, so that a + b + c = 3 the inequality a^2 + b^2 + c^2 >= 3 is true

torpid lintel
#

the only thing that comes to mind is
((a+b)+c)^2 = a^2 + 2ab + b^2 + 2ac + 2bc + c^2 = 9

#

so

royal basin
#

and you have shown in a previous exercise that a^2 + b^2 + c^2 ≥ ab+bc+ca, so...

torpid lintel
#

seriously?

#

i don't see it

#

nvm

#

thanks

#

.close

obtuse pebbleBOT
#
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torpid lintel
#

.reopen

obtuse pebbleBOT
#

torpid lintel
#

actually give me a sec

stable breach
#

have you heard of rearrangement inequality?

torpid lintel
#

no, but i've solved this q

torpid lintel
stable breach
#

nvm

#

your issue is that you dont know a^2 + b^2 + c^2 ≥ ab+bc+ca right?

torpid lintel
#

nah, i've proven it b4

#

just didn't realize it

stable breach
#

then whats ur issue

torpid lintel
#

nothing

#

i've solved this q

#

.close

obtuse pebbleBOT
#
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stable breach
#

oh ok

torpid lintel
#

.reopen

obtuse pebbleBOT
#

torpid lintel
#

@stable breach would you help me with another question?

stable breach
#

ok

torpid lintel
#

i have to show that for nonnegative reals such that x>= y the inequality x^4 + y^4 >= 2xy^3 is rtue

#

here's what i did

#

(x^2+y^2)^2 >= 2xy^3 + 2x^2 + y^2

#

(x^2+y^2)^2 >= 2xy^2 (x+y)

#

and don't know what to do now

#

maybe write it as

#

((x+y)^2 - 2xy)^2 >= 2xy^2 (x+y)

#

and rty to divide by x+y

#

what do you think

stable breach
#

i know at least 2 ways to do it but they both involve inequalities that might not be suitable for your course

#

1 is by rearrangement which you do not know

#

the other is by muirhead

#

have you heard of muirhead?

torpid lintel
#

no, i'm in highschool, and an esl, so i might know rearrangement

#

so let's try it

stable breach
#

all right

#

wait is this school work

#

or olympiad maths

torpid lintel
#

no

#

it's just a highschool graduation exam preperation book

stable breach
#

oh then ig you dont need to muirhead

#

right

#

so let $\sigma_1, \sigma_2, \sigma_3, \cdots, \sigma_n$ be a random permutation of the numbers $1, 2, 3, 4, 5, \cdots, n$

warm shaleBOT
#

A Fellow Human

stable breach
#

so e.g. for $n=3$ you could have $\sigma_1=3, \sigma_2 = 1, \sigma_3=2$

torpid lintel
#

permutation was the one where order matters, right?

warm shaleBOT
#

A Fellow Human

stable breach
#

yeah order matters here

#

does this make sense?

torpid lintel
#

yeah sure

stable breach
#

so you could visualise this as getting a list of the first $n$ integers, then randomising the order, then $\sigma_i$ is the ith element of the list

warm shaleBOT
#

A Fellow Human

stable breach
#

if that makes sense we'll go ahead

#

so let $x_1\geq x_2 \geq x_3 \geq \cdots x_n$ and $y_1\geq y_2 \geq y_3 \geq \cdots y_n$

warm shaleBOT
#

A Fellow Human

stable breach
#

so rearrangment says $x_1y_1+x_2y_2+\cdots+x_ny_n\geq x_{\sigma_1}y_{\sigma_1}+x_{\sigma_2}y_{\sigma_2}+\cdots+x_{\sigma_n}y_{\sigma_n}\geq x_1y_n+x_2y_{n-1}+\cdots+x_ny_1$

warm shaleBOT
#

A Fellow Human

stable breach
#

take some time to take that in

#

for the case $n=2$ that more or less says $x_1y_1+x_2y_2\geq x_2y_1+x_1y_2$

warm shaleBOT
#

A Fellow Human

torpid lintel
#

take some time to take this in?

#

this just says that if you have some order

#

then terms which are products of numbers in this order are greater than terms which are products of numbers in this order but randomized

stable breach
#

yeah

torpid lintel
#

so it seems like some obvious fact, i'm not sure how would you go about using it

stable breach
#

right

#

so if $x\geq y$ then $x^3 \geq y^3$

warm shaleBOT
#

A Fellow Human

stable breach
#

so by rearrangement $x\cdot x^3+y\cdot y^3\geq x\cdot y^3+y\cdot x^3$

warm shaleBOT
#

A Fellow Human

stable breach
#

and $\frac{xy^3}{yx^3}=\frac{y^2}{x^2}\leq 1$ so $yx^3\geq xy^3$

warm shaleBOT
#

A Fellow Human

stable breach
#

so that gives us $x^4+y^4\geq xy^3+yx^3\geq 2xy^3$

#

qed

warm shaleBOT
#

A Fellow Human

torpid lintel
#

let me think about it

#

thanks anyways

#

i might dm you in a bit

#

.close

obtuse pebbleBOT
#
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stable breach
#

sure feel free

#

(this should also be provable with am-gm tho i will need to think about it)

obtuse pebbleBOT
#
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dense dirge
#

find the number of pairs (a,b) of natural numbers such that b is a three - digit number, a + 1 divides b - 1 and b divides a^2 + a + 2

dense dirge
#

I would appreciate a step by step explanation coz its not that easy to wrap my head around...

obtuse pebbleBOT
#

@dense dirge Has your question been resolved?

dense dirge
#

<@&286206848099549185> ?

obtuse pebbleBOT
#

@dense dirge Has your question been resolved?

dense dirge
#

sad

#

just sad

clear girder
#

you have to solve it with no computer help right?

dense dirge
#

yep

crisp depot
#

Sorry, I am not entirely sure how to solve this

#

Or what field of math this would go in...

#

I know though we can limit 'b'

#

And try to see if we can narrow it down

final tartan
#

just 900 numbers to try

clear girder
#

okay it is pretty ez, just choose for b 1 and for a 1.

#

$2|0, 1|4$

warm shaleBOT
clear girder
#

or not XD?

final tartan
#

they are not 3-digit

clear girder
#

trueeeee XD

crisp depot
#

I am curious on this solution, can you explain the what appears to be absolute value signs?

void pelican
#

2 divides 0

#

1 divides 4

#

I believe

crisp depot
#

2 divides by zero?

void pelican
#

no

crisp depot
#

That doesn't seem right

void pelican
#

it basically means 0/2 is an integer

#

and 4/1 is an integer

#

it's kinda a backwards division

crisp depot
#

Oh

void pelican
#

at least that's how I look at it

crisp depot
#

How would that lead us to the answer?

void pelican
#

idk

timid silo
#

trial and error hmmGe

crisp depot
#

I would approach it by making $c = a + 1$ and $d = b - 1$

warm shaleBOT
crisp depot
#

Which would eliminate numbers just above or below prime numbers

#

And all other numbers who are both not made of the same prime factors

#

Which narrows it down quite a bit

#

Then eliminate based on the last rule

final tartan
#

a and b are even or a and b are odd based on the first rule

#

i honstly don't think it has a sol

final tartan
# final tartan

I added the equations on the right but ended up with a=<0
so either my method is wrong or it really has no sol

obtuse pebbleBOT
#

@dense dirge Has your question been resolved?

next violet
#

@dense dirge you asked for a step by step solution?

dense dirge
#

yep

next violet
#

ok here let me try

#

let there be some integer n such that

#

b-1 = n(a+1)

#

thus b=na+n+1

#

it is known that b|a^2+a+2

#

or na+n+1 |a^2+a+2

#

then from further simplification na+n+1 is divisible by -a+2n

#

now na + n + 1 must be divisible by 0, and then you can just plug in 2n for a and plug that into b and find all numbers of that form

#

thats a bit tricky

#

is this a competition problem?

dense dirge
#

yep

next violet
#

ok

#

that makes sense

dense dirge
#

the given answer was way too hard

twilit knot
next violet
obtuse pebbleBOT
#

@dense dirge Has your question been resolved?

obtuse pebbleBOT
#
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timid silo
#

$\int_{\gamma} f(z)\abs{dz}=\int_{-\gamma} f(z)\abs{dz}$

warm shaleBOT
#

Cüneyt

timid silo
#

is this correct?

obtuse pebbleBOT
#

@timid silo Has your question been resolved?

obtuse pebbleBOT
#

@timid silo Has your question been resolved?

royal basin
#

i remember you asking this very same question multiple times and the conclusion being that nobody here has any fucking idea what this notation is supposed to mean

timid silo
#

Lol

#

But I need to find it out

#

It may be in my exam

royal basin
#

then why ask here and not your professor?

timid silo
#

Because he told us if it is correct and I didn't listen to him at that moment

#

I don't wanna ask

royal basin
#

well you will have to

timid silo
#

Okay one more question and Ill close the channel

#

Is this correct

royal basin
#

????

timid silo
#

Check real-Complex anaylsis

#

.close

obtuse pebbleBOT
#
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honest jewel
obtuse pebbleBOT
honest jewel
#

how would i do b>?

junior inlet
honest jewel
#

what if formula for perpendicular lines

junior inlet
#

slope of the line perpendicular to y=mx+c is -1/m

honest jewel
#

so y=mx + b form would be

#

x = 1/2y - 2

junior inlet
#

well

#

actually, you can continue with that, but it will be a bit different

honest jewel
#

oka

obtuse pebbleBOT
#

@honest jewel Has your question been resolved?

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timid silo
#

i am working with natural logarithms and would like to know how in this workings out how the -t becomes positive?

hushed moat
#

the -ln(1/2) becomes ln(2)

#

then t=10ln(2)

timid silo
#

so from -t/10 i understand that we take -10 from both sides

#

hence the -10 ln1/2

hushed moat
#

yes

timid silo
#

but that would leave -t

#

-t = -10ln1/2?

#

how does the -t become positive?

hushed moat
#

nono, the minus sign cancells out

#

$-10 \cdot -\frac{t}{10} = t$

warm shaleBOT
#

Frosty

timid silo
#

wait

#

so

hushed moat
#

when you multiply by -10

timid silo
#

i am not multiplying i am subtracting

hushed moat
#

otherwise you wont get t on it's own

timid silo
#

i just thought of something

#

can i divide both sides by -1

hushed moat
#

yea

timid silo
#

that will give +10.....

hushed moat
#

but that's not the right equation

#

$-\frac{t}{10} = \ln(\frac{1}{2}) \ -t = 10\ln(\frac{1}{2})$

warm shaleBOT
#

Frosty

hushed moat
#

that is just multiplying by 10

#

now you can divide by -1 or whatever

timid silo
#

right

#

i think i got

#

multiplying both sides by -10 worked

#

thanks man i knew i was missing something simple

#

.close

obtuse pebbleBOT
#
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timid silo
#

hello

obtuse pebbleBOT
timid silo
#

quick question

#

if a triangle has three equal angles does that mean all sides are equal

#

?

little basin
#

yes

timid silo
#

okay thanks

#

.close

obtuse pebbleBOT
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timid silo
#

Suppose I have:
sin(2x) = sin(x)

obtuse pebbleBOT
timid silo
#

So I say:
2 sin(x)cos(x) = sin(x)

#

can someone explain why dividing both sides by sin(x) will hide one of the values of x?

high lily
#

you lose the solutions from sin(x)=0

#

will hide one of the values of x
in fact you're lose infinitely many solutions

timid silo
timid silo
#

Because I'm dividing by zero or because I no longer look for sin(x) = 0?

high lily
#

consider approaching the question with factorisation

#

you're dividing by something that could potentially be 0

timid silo
high lily
#

like lets take a cubic equation in factored form
x(x-2)(x-7) = 0
you wouldn't blindly divide both sides by x, (or (x-2), or(x-7)) would you?

timid silo
high lily
#

generally applies

timid silo
#

This brought the idea closer to me so thanks

high lily
#

don't divide

by something that could potentially be 0
unless you really know what you're doing

timid silo
#

Alright 👍

#

.close

obtuse pebbleBOT
#
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static patio
obtuse pebbleBOT
static patio
#

for all n >= 0

#

is it a subspace ?

#

i dont know how to check subspace properties when its a sequence

runic trout
#

For closure, pick (a_n) and (b_n) from the set. They satisfy the recurrence relation. Consider (a_n + b_n) and (k a_n). Check whether they satisfy the recurrence relation.

static patio
#

hmm

#

i dont get it tbh

#

can you show me little example ?

runic trout
#

Prove that V = {(a_n) in R^N : a_i = a_{i+1} } is closed under scalar-multiplication. Pick (a_n) in V and k in R. Consider (k a_n) = (k a_0, k a_1, k a_2, ...). For any subscript i, since a_i = a_{i+1}, we have k a_i = k a_{i+1}. This shows that (k a_n) is in V.

#

For closure under addition, pick another (b_n) in V. Consider (a_n + b_n) = (a_0 + b_0, a_1 + b_1, ...). For any subscript i, we check that a_i + b_i = a_{i+1} + b_{i+1}.

#

We also need to check that the zero sequence is in the subspace.

static patio
#

thanks a lot

#

i got it

#

.cloose

#

.close

obtuse pebbleBOT
#
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dapper geode
#

can someone explain the steps here

obtuse pebbleBOT
dapper geode
#

when I_1 =

#

and I_2 =

twilit loom
#

The first term $\frac{ae^{-il_2a}}{-il_2}$ of $I_1$ and the first term $\frac{(1-a)e^{-il_2a}}{il_2}$ of $I_2$ cancel each other out when summed

warm shaleBOT
#

dino dik

twilit loom
#

Then the factor of ${1\over l_2^2}$ is factored out, ending up with the top expression

warm shaleBOT
#

dino dik

obtuse pebbleBOT
#

@dapper geode Has your question been resolved?

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dark steeple
obtuse pebbleBOT
dapper geode
#

first but x-1 in g(x)

dark steeple
#

ok

dapper geode
#

then put that in f(x)

#

ah wait

#

is that

#

g*f

#

or g(f(x))

dark steeple
#

gf(x)

#

is

#

g(f(x))

#

yeah

#

but

dapper geode
#

ah ok

dark steeple
#

how do u do it with x + 4

#

i dunno know that

dapper geode
#

put f(x) in the x of g(x)

dark steeple
#

wait lemme do it

#

how do u do the first part

#

so

#

x^2-25 * x+ 4 *X+1

scarlet gale
#

@dark steeple What's fg(x + 1) simplify to?

dark steeple
#

(x+1)

scarlet gale
#

No.

dark steeple
#

OH

scarlet gale
#

fg(x + 1)
f(g(x + 1))

dark steeple
#

so

scarlet gale
#

Now, to do g(x + 1), you do this:
g(x) = x + 4
g(x + 1) = (x + 1) + 4

#

See how you replace x with x + 1 on the left?

dark steeple
#

so is it x+4 * x+1

#

g = x+4 * x+1

scarlet gale
#

Do you see how I replaced x with x + 1 on the left?

dark steeple
#

yeha

#

yeah*

scarlet gale
#

So because I replaced x with x + 1 on the left, I also did it on the right.

#

And I put it in parentheses to avoid mistakes.

#

g(x) = x + 4
g(x + 1) = (x + 1) + 4

#

Does it make sense what I did?

dark steeple
#

yess

#

so it will become x^2

#
  • 1x
scarlet gale
#

Stop working ahead please.

#

I'm trying to show you a method to solve these.

dark steeple
#

oh

#

sory

#

my bad

scarlet gale
#

OK, so

f(g(x + 1))
f((x + 1) + 4)

Now we do the same thing with f.

f(x) = x² - 25
f((x + 1) + 4) = **((x + 1) + 4)**² - 25

#

See how we had x on the left and replaced it with (x + 1) + 4?

dark steeple
#

oh

#

ok

scarlet gale
#

Then you do the same on the right, but with parentheses around it.

dark steeple
#

kk

scarlet gale
#

So, you do the same thing to both sides.

dark steeple
#

right

scarlet gale
#

You replaced x with something on the left, so you replace x with it in parentheses on the right side.