#help-26
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Hi there how do i solve this im in high school and not very good at calculus
$$\frac{d}{dx}(\frac{x}{(a^2 + x^2)^\frac{3}{2}})$$
is z meant to denote a complex numbe
skygazer2239
you can either start with quotient rule, or change the 3/2 exponent to -3/2 and do product rule
one of the parts is just x, which is simple to deal with, the other will require some chain rule applications
Im not smart enough to perform chain rule on the denominator thats what i need help with i should’ve mentioned sorry for that
I'll just focus on $(a^2+x^2)^{-\frac{3}{2}}$ for now then
Desync
so the inner function is $a^2+x^2$, and the outer is $(-)^\frac{3}{2}$
Desync
Ok
what's the derivative of the inner function wrt x
(I missed a minus sign in the exponent there, it should be -3/2)
2x
No problem i got that
0
consider it as $x^{-\frac{3}{2}}$
Desync
what's the derivative wrt x
Sry
so when you subtract 1, it should become more negative
in the exponent yeah
Ok
so putting it together, we have $-\frac{3}{2}2x\left(a^2+x^{2}\right)^{-\frac{5}{2}}$
Desync
A question
Why did we do this?
you take the derivative with respect to the inner function
the chain rule tells you how the composition of two functions varies
you need to know how the outer function varies with respect to its input (i.e. wrt the inner function)
Ohk
as well as how the inner function varies
Is this like substitution?
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I need to clear this up wait a minute plz
So the whole derivative becomes this..?
@main shale
sure
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im unsure if it's true or false. my linear algebra intuition says true, but my geometric intuition says false
linear algebra: B spans V, so B spans W, so some subset of B must be a basis for W
is this for a test
also, this is false
@vivid charm this is false
B must span W, yes, but it is not necessarily a basis
or well whats wrong with my linear algebra intuition
No member of B has to be confined to W
For instance consider a general plane in 3d space
This plane is a subspace
e.g., B = {(1,0), (0,1)}, and V = R^2
if you say W = span{(1,1)}, no restriction of B will be a basis for W
but B still spans W
But might not contain any the standard basis
yea i have a counter example too, but how is #help-26 message not true
well W can be lower dimensional
so why should B be a basis
B will certainly span some set containing W
but it won't necessarily have the correct number of vectors
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If $f: A \to B$ and $A_1, A_2 \subseteq A$ with $B_1, B_2 \subseteq B$, show that $A_1 \subseteq A_2 \implies f(A_1) \subseteq f(A_2)$.
So, let $x \in A_1 \subseteq A_2$. Then $f(x) \in f(A_1)$, but also, since $x \in A_2$, it is in $f(A_2)$.
Good enough! Just end with "so f(A1) \subseteq f(A2)" and you're done
Is this really all?
yup! you could be more explicit by saying since x \in A1 and A1 \subseteq A2, this implies x \in A2
Yeah, this is probably better, because I could change up the proof a bit and end up with
So, let $x \in A_1 \subseteq A_2$. Then $f(x) \in f(A_2)$, but also, since $x \in A_1$, it is in $f(A_1)$. Thus $f(A_2) \subseteq f(A_1)$.
And with this argumentation, this won't work anymore
Thank you
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I found the gradient but not sure how to find the directional derivative
The directional deriv I had to look up to find
@honest mantle Has your question been resolved?
No, I don’t know how to find the directional derivative in this situation, I had to look it up to get the solution
If you have the gradient, the directional derivative is just the gradient dot u
in this situation its asking for the directional derivative in the direction of maximum rate of change
that's just the gradient again so you get
gradient dot gradient i.e. the magnitude of the gradient squared
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Can someone teach me how to solve this manually
Please don't occupy multiple help channels.
If it's of any help it's part of another integral going from zero to infinity
u-sub should be good here. Have you given it a try?
yeah but it just keeps getting more complicated
if you substitute t = u^(10/49) , what do you get for dt/du?
(at least if I do integration by parts) but I don't know any other way
maybe u^(10/49) as u^(-39/49 + 49/49) idk
-e^-t? not sure tho?
you also have to substitute the du by dt, thats why you need the derivative dt/du
think of it as t(u) = u^(10/49) , then t'(u) = dt/du = ...
svc gkawpogklawg
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For what values of a parameter m the function f(x) is increasing in the interval ]-3,0[?
Zachy
what have you tried?
,w D[m x^4 - (m+2) x^2, x]
and I got the interval that m <= 12/102
and then I tried graphing it and I got that the anwser is [-2, 12/102], but I don't know where that -2 comes from
its so weird because it seems like the answer would be way lower 
oh -3 0
1s
i can explain where the -2 comes from
but i dont understand how you got the 12/102
we can trade hahaha
but my overall apprach was this:
- prove that the gradient for argument -3 is non-negative
- prove that the gradient for argument 0 is non-negative
- prove that there are no points of inflection in between
so this is how i got 12/102
jan Niku
jan Niku
(we dont have to assume, since x=0 is not included in the interval ]-3,0[ )
this implies that $x=\pm \sqrt{ \frac{m+2}{2} }$
jan Niku
quadratic formula, right?
yes
i got that too, but scrapped the idea
well the important part is the discriminant
i see where the -2 comes from
yea
yea, i meant discriminant
you can think of this as a bifurcation if its helpful
maybe its not 
but lemme find something for you here
nope it is not
you can see the two boundaries here
@merry phoenix
the horizontal axis is m
the vertical axis is f*, places where f is fixed (where f' = 0)$
so the black lines are boundaries between places where f' is positive or negative (red and blue)
if thats nonsense dwai
but you can clearly see the appearance of additional roots of f' on the left and right, which is cool
yea im gonna choose to not worry about it
cool, but way beyond comprehesable to me lol
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Object A contains 30 g of salt in 500 ml of water. And object B is unknown then concentration of salt water when these two substances are mixed is 2/35 then what is concentration of B
I got negative value for B when I tried to set 30/500 + B = 2/35
540
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how many mL of water does object B have
700
edit your question to include this information
if the problem tells you that object B has 700mL of water, then you have to put that in
this is also not correct
if you add Object A + Object B together, you would then ahve to add 500mL of water + 700mL of water = 1200mL of water instead of 540mL
@shrewd atlas please take a picture or to take a screenshot of the question
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tried the second one, unsuccessful
but almost there
in the solutions they do this. which is quite confusing to me. Is my way acceptable too? at least for the first part of the exercise
basically my question is, do I really need to learn all of these?
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So I took this linear algebra test a while ago and I wasn't able to solve this question, now I'm trying again and I think I solved it but I'm quite rusty and these types of problems always confuse me. I'm not sure if my answer is correct [TRANSLATION: "given g the linear transformation defined as... Define if possible, a linear transformation f:R^4->R^4 such that..."]
my answer:
I'm pretty sure I got it because I tried to show that f fulfills all the requested conditions but I just wanna make sure
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gallia please enlighten us on what’s troubling you
I just want to know if my answer is correct
I checked myself but with these types of problems I'm never sure
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could someone please explain how to answer part B of this question to me? i know my answer has to include what side the distribution of each employees sales is skewed to, or if the distribution is symmetrical, but i don’t really understand how to figure out skewness in stem and leaf plots
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i know the formula and the ans . then what do i do it says calculate the total amount
yes
206.045
pretty sure this is correct
it is
bt
but
it said calculate the total amount
this is thw ans
but u just said that 206.045 alone is correct.
ok
y=kx
?
so what is it 0 or x+2
cubed
o
oh
lemme try to solve
nope im lost
then what
yep
then wha
k=4
no 8
how 4
?
4
i thought he said 2 cubed is 4
so then we divide both side by 32 or
or both side by 8
oh
k= 4
now i will find y
i got 108
i got k= 2 and y= 512
am i corrrect
..
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hey can anyone help me with this problem:
The radius and height of a cylinder are in the ratio 5:7 and its volume is 550cm cube. find its radius?
i think its pi R spquare H
$\pi r^2h$
flurry
yep
yea
however we know that the ratio of radius and height is 5:7
let 5x and 7x be the radius and height respectively
ok
flurry
i need to find its radius
when you equate this volume to the given volume
you find 'x'
and then 5 times x is the radius
ok let me try
22/7 times 25x^2 times 7x
hey idk how but i somehow got 12100 = 25x^2 times 7x now what should i do
hwlllo?
@fervent furnace Has your question been resolved?
noooooooooooooooo
hello any genius here
nvm
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Can someone please help me with this FFA question. Am I on the right track and if so what should I do next? Thank you in advance!
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I'd post this in #advanced-analysis
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Using 4 colours, in how many ways we can colour the vertices of this graph such that every two vertices that are adjacent have distinct colours?
call the colors a,b,c,d.
if you color, for example, 5
what does that force upon 6,7,8?
C(6),C(7),C(8) are not C(5)
yea, but can you say something even stronger than that
But C(8) is not C(6) and not C(7)
so the inner 4 all need to be distinct
how many ways are there to make the inner 4 distinct?
if you struggle to approach your problem
you can try a simpler problem
the answer is 36
it has a similar approach and ig you can build a base with this
Hmm
yea i would prolly just think about each of the three cases for ways to color 1
two of them are the same (yellow and purple), but i think casework is the best way here

I started with 1 and then i got in so many cases ://
yeah without the two diagonal edges for the inner vertices the problem becomes significantly harder (or you can just use wolfram alpha to find the chromatic polynomial for a cubical graph)
i only see two cases
the outer ring has 4 colors, or the outer ring has 2 colors
ok it could be 3 i guess
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given a point in Rn x_k = (xk1, xk2,...,xkn) will converge to x = (x1,x2...,xn) iff xki all approaches xi as k tends to infinity for each i
now a hint is given such as
"important observation" is |x_j| <= ||x|| (1<=j<=n) for any x in Rn
how is that possible? even for R the real number line, xk while converging to x can be bigger or smaller anytime wont they?
pay attention to | | and || ||
the hint basically says the length of x cannot be less than the lengths of any of its components
if you want to imagine it in R^2 or R^3 or whatever
isnt the norm and the mod value for x would be same for the euclidian distance of the real number line? is distance from origin
i mean when I am talking about only the R not the R^2 yet
yea sure
|x_j| = ||x|| for 1<=j<=1 in that case
still agrees with the hint
that is hwat i am saying that x_j is only a sequence
while x is a fixed vector
x_j can sometimes be greater sometimes be smaller depending upon j
o ok i see the confusion
treat the notation in the hint independently from the question
the x_j's are the components of x
awww okay that is a well explanation
but still it will still bug me that if it is possible for all n, it should be possible for n=1
wait no no uhh my bad
x_j is the individual component not a sequence as per my question
x_j ie the jth component my bad
thanks @wary tulip

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Sort of a programming question but it's not related to any language so I thought I'd ask here.
When working in a coordinate grid, you can use a ceiling function or a floor function to get which "square" of the grid you are in. Something I was wondering is how you would go about doing the same but for a hexagonal 2d grid.
part of the localization when you do it on a grid is that there is a natural way to number the grid squares by row/column
how do you identify the hexagons in the grid?
is that a rhetorical question?
mo
no
when you take a point and ask for the grid, the output is a tuple (row, col)
to identify the square
what kind of output are you looking for here
ok gotcha
basically for a given coordinate on a plane, with a hexagonal grid that is much larger than the scale of the coordinates on the plane, I'd want to be able to get the coordinate of the centre of the current hexagon
for a square grid I just used a floor division function to get a whole number for the x and y coordinate of the square, but I can see that that would be harder with a hexagonal grid
e.g. if the coordinate is at x 81 and the size of the grid is 20 units, the current square would be x 4
though I think that obtaining the coordinate of the hexagon's centre would be sufficient
the important thing is that each hexagon has its own unique x and y coordinate so I don't think it really makes a difference if a normalised coordinate is used or if the real coordinate is used
you could use a small amount of heurestics to do this fairly quickly
given an arbitrary point, you can find the closest 3 hexagon centers with a small amount of math, and then just compute which is the nearest of the three by taking their squared distances and finding the minimal one
a single formula derived from this method would be a piecewise function like a floor/ceil for the grid case, but would be pretty unwieldly
the general algorithm should be straightforward though
if that sounds useful lmk and i can expand, otherwise someone else will have to help cause im not sure i could derive a nice single formula for it
alright well given a hex grid, adjacent centers form equilateral triangles
i shouldn't have started with that sorry
let me instead say that there are nicely defined rows and columns by the centers of the hexagons
sort of like this
I see
so given a point (x,y), you can find between which of these red and blue lines it lies
via the grid method you mentioned earlier
and in fact, given a single grid there is 2 closest centers, not 3 like i said earlier
yep that makes sense
all you'd need to do now is locate which grid you're in, then find the distance to the yellow corners for that grid, and take the minimal one
the actual numerics are a bit annoying but if you give me a minute i may be able to derive them, though hopefully you should too if you understand the picture im drawing
I had an idea but I'm not sure if i's the same as what you're getting at
real quick, are there any specifics as to the hexagons you're working with? does the grid have a hexagon centered at (0,0)? how are the hexagons defined?
as in, are you given their side lengths
it's a purely conceptual question atm but you would know the side lengths or the diameter of the hexagons yeah
though like you said most of this in normalized coords should be easily translatable
ok so supposing we have a hexagon centered at (0,0) with side length s, the distance between those red lines will be s * sqrt(3)/2, and the distance between the blue lines will be 1.5s
that means that if you want to find which of the grids you're in, you would take the point (x,y) and map it to (floor(2x / (s * sqrt3)), floor(y / 1.5s)), which should give you the bottom-left corner of the appropriate grid
well that's the index of those at least, so to get the actual corner you'd multiply the coordinates by s * sqrt(3)/2 and 1.5s respectively
so say we have a bottom-left corner (u,v), in order to get the other corners we simply take (u + s * sqrt(3)/2, v), (u + s * sqrt(3)/2, v + 1.5s), (u, v + 1.5s)
all that's left is to check which are actual yellow hexagon centers and which are "fake" centers
given the indeces we found earlier, (i,j) = (floor(2x / (s * sqrt3)), floor(y / 1.5s)), you should be able to just take the parity of i + j
if i + j is even, the bottom-left is a yellow center, otherwise it is a flase center
all that's left is to take the other yellow center and find the one with the smaller distance to the point. that will be the center of the hexagon the point lies in
yeah back here I was thinking you would have to check if you're on an even or odd rectangle to work out which corners to check
good to know I was on the same page
there may be some slight inacuraccies in the numbers i mentioned above, and some redundancy even, but the idea should be logical
yep
and if you really wanted to, this could be a single piecewise function, though that would probably be horrid
quick question, since I'm guessing this would be even easier if you know the length of one section of the red lines and one section of the blue lines, what ratio do those distances have to be in order for the rectangular grid to be "made into" hexagons?
if they're not at a specific ratio you would have a skewed hexagonal grid right?
Right triangle where the red intersects the blue
If you know your trig functions, that's tangent
.. or it's just slope if you're not into trig yet.. rise / run
red / blue
i sort of derived the rectangular grid from the hexagons, so kind of opposite of what you said
the actual scale of the green arrows you drew doesn't really matter
yeah I get you it's kind of the opposite
in general, as long as the rectangular grid makes a right angle, the algorithm we discussed above should work to find which hexagon you lie in
but
if you were to care about a skewed grid (the red and blue one), all it would take would be to unskew the point, solve the problem there, then reskew
hmm
i also quickly wanna mention that while the algorithm above is a bit annoying and complicated, it is still O(1)
yeah that's good for sure
my thinking was that if you applied the algorithm to a rectangular grid of a slightly different length, the hexagons would be either stretched horizontally or vertically
thats right
so there must be a ratio of the distance between blue and red lines where the algorithm assumes regular hexagonal centers
ah i see. the ratio is sqrt(3) : 3
for an arbitrary side length s for a regular hexagon, the red lines will be s * sqrt(3)/2 units apart
the blue lines will be 1.5s apart
so their ratio would be sqrt(3) to 3
that makes sense, thanks for the help.
I mentioned originally that this was somewhat a programming question. So I think it would be even easier if you were to start with the distance between the blue lines, calculate the distance between the red lines, then for a particular coordinate (after working out which rectangle it is in) work out which two of the corners you need to compare the distance of to get the closest centre.
And it is definitely useful to know how to do it starting with the length of one of the sides of the hexagon, too.
well you can get the distance between the red and blue lines given the sides of a hexagon immediately
so they are essentially the same problem
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can this be simplified
or should I just leave it as it is since it is such huge numbers
did you try writing it out in terms of factorials to see if you can cancel anything?
no I haven't
i dont deal with probability often but the answer as I have is alright to display right?
it doesnt always hve to be super exact?
sure, unless someone asks you to simplify it
okay
cause im looking at previous assignment solutions and like answers with binomial with like multiple powers on them are just left as it is
and I'm honestly 2 lazy to actually simplify if I dont have to 😭
thank you tho
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you can see by taking the dot product of x and v that they are not perpendicular
when you take a cross product, the j should be multiplied by -1
i thought it's just minor and cofactor expansion
so it should be [-10, 3, -1] ?
oh right
so this is the answer?
the dot product = -32
looks like you did 7 * -2 wrong
well you did 4 * -2 and 7 * -1 or something
oh never mind i was looking at k, my bad
oh
no i meant take the dot product of the vector you found
with u
and then the dot product of the vector you found with v
to make sure it is orthogonal
oh, that equals 0
-10(2) + 3(7) + (-1)(1) for u
and 0 for v
-10(-1) + 3(-4) + (-1)(-2) for v
so both dot products = 0
so that means the correct answer is [-10, 3 -1], right?
if the dot product of two vectors is 0, the angle between them is 90 degrees
tyvm
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Can anybody give me a rundown on just how to do basic proofs with parallelograms? I'm in a geometry class and I am completely lost on how to do this stuff. Heres an example from my homework:
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ok so you need help on proofs
do you know the theorems for them?
I mean, sorta? i know like the properites that make up quadrilaterls and stuff and all the angle and side proofs. in the assignment it already has them labeled, but on the test I have I would assume that they would require us to know by memory
ok so next step would be to use the midpoint theorm to prove that BC and AD are similar i think
how would that work?
also ik its both properties but would i do BC II AD or BC ~= AD
BC~= AD
all good haha
@gritty crater Has your question been resolved?
Just look at it bro
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How do i solve this question? my main doubt is what do I do with the variable n
work with it like you would another number
a good place to start would be to do some factorisation on the numerator
If It was just another number I'd somate both and create a new expoent
cant we write the 2.2^n as 2^n+1?
do you know your exponent laws
i do?
Would It become 2^4n @restive inlet ?
what's "it"
Can you you solve just one of the ones that have a variable so I can see how would do It ?
2^n+4
n+4 isn't the same as 4n
that will be 2^n * 2^4
Can you do only the First step of this question so I can see what do I do?
😭.
do you know your exponent laws?
Multiplying potentiation you somate expoent, dividing potentiation subtração exponent
consult a list of exponent laws if needed, can you find another way to express
$$2^{n+4}$$
(this form will usually appear on the right side of the equation of such lists)11
ℝαμΩℕωⅤ
yes
But which one of those apply to this situation
lookcing at the right sides of the equation, what does $2^{n+4}$ resemble/look the closest too
ℝαμΩℕωⅤ
Power of Power rule
no
on the right side of that equation/rule, there is a product in the power
which isn't what you have here
note that in the power here, you have: $n \red{+} 4$
ℝαμΩℕωⅤ
Power of quotient?
no
Quotient of Power?
Product of power
Wouldnt that be true only If 2^n+4 was multiplying instead of subtracting 2.2^n?
starting from one side, you can get to the other
i.e. with 2^(n+4), you're starting from the right side of that product of powers rule
which will allow you to express it in the form on the left
I thought that I could only use product of Power rule when they were multiplying each other
from the rule
$$x^{m+n} = x^m \cdot x^n$$
and apply that to
$$2^{n+4} = \what$$
But there is a minha there between then
ℝαμΩℕωⅤ
Aaaaa
I think i get it
Wait
Lets me try to solve the question by myself now, wait 5 minutes
This is what you were trying to explain me, right? @restive inlet
Can I simplify the numerator using the denominator
?
Like cutting -2 by 2 ? @restive inlet
no, that will not be legal
you can't just cancel / erase expressions that happen to appear "somewhere" on the numerator and denominator
fraction simplification results from cancellation for common factors
$$\frac{\cancel{p}(q+r)}{\cancel{p}(s+t)} = \frac{q + r}{s + t}$$
ℝαμΩℕωⅤ
note that you have like terms on the numerator
some multiple of 2^n - another multiple of 2^n
They were common factors though
2 and ,- 2
Hi Evry one
Or numbers with different signals arent common factors?
in those terms yes, but you're cancelling 2 from a single term on the numerator
instead of a factor of 2 from the whole numerator
you can't do much clean cancellation of $p$ if you have stuff like
$$\frac{p+q}{p+s}$$
ℝαμΩℕωⅤ
So I need to make a factorization first?
I'll try do one and show you, wait a second
I cant find a good vídeo about how I do factorization in this scenario 🥲
could just view it as combining like terms
how would you simplify something like
$$\red{7}\blue{x} - \violet{3}\blue{x}$$
ℝαμΩℕωⅤ
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Are you sure ?
incorrect
i dont know
if you had 7🍎 and someone stole 3🍎 from you, how many 🍎 would you have left?
4 apples
yes
same principle applies to the simplification of 7x - 3x,
just instaed of apples, you have x there
and same principle also applies to the numerator of what you have,
just instead of apples or x, you have 2^n
$$\red{7}\blue{\text{apples}} - \violet{3}\blue{\text{apples}} = \underbrace{4}{\red{7}-\violet{3}}\blue{\text{apples}}$$
$$\red{7}\blue{x} - \violet{3}\blue{x} = \underbrace{4}{\red{7}-\violet{3}}\blue{x}$$
on the numerator you have
$$\red{2^4}\cdot \blue{2^n} - \violet{2}\cdot \blue{2^n}$$
ℝαμΩℕωⅤ
Let me try do It again
What do you think now?
I'm on the correct direction ? @restive inlet
no
state the specific rules/laws are you applying to the numerator to get $2^n\cdot 2^3 \cdot 2^n$
ℝαμΩℕωⅤ
Multiplying number with same base you sum the expoent
how exactly was that being applied to
$$2^4 \cdot 2^n - 2\cdot 2^n$$
or
$$2 \cdot 2 \cdot 2\cdot 2 \cdot 2^n - 2\cdot 2^n$$
to get
$$2^n \cdot 2^3 \cdot 2^n$$
ℝαμΩℕωⅤ
I added the expoent of the 2^¹•2^¹•2^¹•2^¹-2^¹=2³
2^4 isn't being divided by 2
Oh, só I wouldnt need to subtract the expoent?
Let me do this again
what i'm trying to get you to do in this step is to simply combine like terms
it may be easier for you here to first use that 2^4 = 16
if you had 16🍎 and someone (me) snatched 2🍎 from you, how many 🍎 would you have left?
What about now @restive inlet
no
when i asked you
if you had 7🍎 and someone stole 3🍎 from you, how many 🍎 would you have left?
you didn't say you'd have
4🍎🍎
did you?
I did
you said just 4 apples
you will not end up with 4 alien weird hybrid double apples
you'd be left with just 4 normal apples
3 apples
16-2 is 14
yes
So where did i do a mistake
you have 2^n twice
you will not end up with 4 alien weird hybrid double apples
you'd be left with just 4 normal apples
instead of apples, you have 2^n
so after subtraction you'd be left with 14 multiples of 2^n
and not 14 multiples of 2^n * 2^n
So It would be 14 • 2^n+n
2^n • 2^n
i literally just said that's what you're NOT supposed to do
if you had 7🍎 and someone stole 3🍎 from you, how many 🍎 would you have left?
you will not end up with 4 alien weird hybrid double apples
you'd be left with just 4 normal apples
14(2^n)
yes
But what happened to the n that were multiplied?
In this case they would be added to each other right?
wdym
like terms were combined
you seemed to understand what happened when apples were involved
exact same idea applies here
I believe number of same base when multiplied you sum the expoent
this part/step was mostly irrelevant to that
Why? I need to know because I have a Exam about that soon
the step i was getig you to perform wasn't really related to those exponent laws
Why one 2^n would disappear and the other stay
but you were trying to improperly incorporate those laws in this step
principle of combining like terms
you seemed to understand what happened when apples were involved
exact same idea applies here
So we are Just combining terms now and nothing else
in that step, yes
yes
I did the change but you need to explain me where the other 2^n ended when this end lol
Can I simplify all numbers by 2?
you should be able to see that 2^n is a common factor of both numerator and denominator
go back to the example i gave with apples
or if you have identical objects lying around in front of you, remove afew of them
in your numerator 2^n is that object
you have a certain multiple/number of that obect,
and a few of those are being taken away
leaving you with a lesser multiple of that object
16 bananas - 2 banans = 14 bananas
16 benjamins- 2 benjamins= 14 benjamins
16 cars- 2 cars= 14 cars
16 yachts- 2 yachts= 14 yachts
16 * 2^n - 2 * 2^n = 14 * 2^n
ℝαμΩℕωⅤ
i've been trying to say this the whole time
starting with 16cars and having 2 stolen from you doesn't result in you have 14 car cars
This question is the Second case with 2^n 2^n
starting with 7 apples and having 5 stolen from you doesn't result in you having 2 apple apples
is this part of a different question now?
It does result in 2 apples
just 2 normal apples we normally see in the real world
Did you cut the 2^n in the numerator with the one in the denominator?
Thanks for your help Man, I'm just stupid
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is this right
yea
I can still keep going by doing factorization on (-x² + 16), right?
I gotta take out the - first though, right?
tysm 👍👍
np
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Im confident I did it right?
Can someone see if I did it right?
For the Kite shown Angle EAB is
49 degrees determine the measure of the angles listed below in degrees
If I didn't do it right can someone tell me a way I could do it? or a method
Ill return
and AC is a bisector
I will return in a few minutes with a new answer using the new given info
EAC is 24.5
Same with BAC
ACD is 90
is EAD really EAB/2 ?
Yeah
AC is a bisector so it divides EAB into two equal angles
but EAB is not the angle that AC is bisector of
But even if it isn't wouldnt it be those still?
I can't find anything else
i cant help further than this sorry
Diagonals of kite intersect at 90 degrees
First one is right but not the other two
ABE 49
AEB 41?
Second one is wrong
You know Angle EAB and you know angle AEB, use angle sum property of triangle and find Angle ABE
180 = 90 +49 + ABE
139
No I had written the - by mistake
oh.
This one, do this
41
Yeah
You know angle sum property of triangle?
yes
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from my understanding, when increasing the index of your sigma, the actual values inside should decrease adn when you decrease the index of your sigma, the values inside should increase. In the questioni above Im confused as to why theres another u^2 multiplied on the ouside
feel like Im missing basic knowledge with these infinite series qs but I havent been able to find great resources 😥
@sharp tapir Has your question been resolved?
you're right, but here they're not exactly shifting the indices because the (k-2)! at the bottom is the same
here it's just saying that (k-2)! doesn't exist for k=0 or k=1, since it's a negative factorial, and also in the step they pull out mu^2
it's always good to check if the first few terms of a sum make sense
someone exaplined the factorial part a little bit ago, so I think I understand the fact that we can essentially ignore the factorial part because its invalid for certain values
but Im not sure what you mean by the fact that they pull u^2
like the top equals the product of the bottom
nah still no shifting just weird math simplifications, here some parts of the factorial are multiplied on top and cancel
yea that makes sense
usually for shifting you have to see all the k's move at the same time along with the sum bounds
so if one of the k's isnt shifting, for example with the k-2! in this case, all of the k's dont shift?
so in this case, the ^k wont shift because the (k-2)! is holding it back in a way?
yea that's what indicates it's not happening
interesting
so if I wanted to shift 1 more, the (k-2)! would actually get efffected this time since it would lead to (3-2)!=1, would this then allow me to shift the ^k-2 to ^k-3
like this:
or would I still ignore it because x/1 = x either way?
right that's what it'd look like
nvm this is dumb
the terms won't suddenly turn bad here no
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in the original image it looks like they're effectively trying to make the summation look like a shifted version of the e^x series by factoring things out, just so they can plug in the value, so it's pretty confusing haha
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What is all other left and right truncatable numbers with ends on number 1? For example 11 is prime, and ends 1. Or 311 is a prime, and 11 is a prime, ends on number 1
Or code to find this in python
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What is all other left and right truncatable numbers with ends on number 1? For example 11 is prime, and ends 1. Or 311 is a prime, and 11 is a prime, ends on number 1
Or code to find this in python
!nogpt
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i think he's asking where you discount the last step needing to be prime (1 not being prime)
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I have the sketched graph for part A and the diff equation I came to is the second image. I plugged in 1 for x and -1 for y but got 0. Not sure what I did wrong
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yes
???
@zenith hollow Has your question been resolved?
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For 7 h)
What should we get after we do u = 1 + e^x ?
i got like (u-1)²/u².
Is that right ?
make u=e^x
it will be more complex i think
$\int{\dfrac{{e}^{2,x}}{\left({{e}^{x}+1}\right)^{2}}}{;\mathrm{d}x}$
prime
if you set u=e^x, du=e^xdx, and it cancels out with the top
$\int{\dfrac{u}{{u}^{2}+2,u+1}}{;\mathrm{d}u}$
prime
prime
$\alpha=u+1$ $d\alpha=du$ $u=\alpha -1$
prime
$\int \frac{\alpha-1}{\alpha^2} d\alpha$
prime
and now you can separate into 2 integrals due to linearity
then replace all the variables
ty
the final answer should be $\ln|\left({e}^{x}+1\right)|+\dfrac{1}{{e}^{x}+1}+C$
prime
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Does anyone have the proof of derivative of e^x?
so do you know the derivative of a^x
or we can proof it too to get that and just substitute a=e
let y=e^x
take natural log both sides
ln(y)=xln(e) (lne=1)
differentiating both sides wrt x
1/ydy/dx=1
dy/dx=y (y=e^x)
dy/dx=e^x
wouldn't that assume you defined the derivative of lny as 1/y already. I think that is a totally valid definition but idk
uh. no that is the proof though and derivative of ln(anything var) wrt x is 1/(anything variable)*d(anything variable)/dx
@kind plinth Has your question been resolved?
by definition of derivative $\lim_{h\rightarrow 0} \frac{e^{x+h}-e^x}{h}$
y0shi
$\lim_{h\rightarrow 0} \frac{e^x e^h - e^x}{h}$
y0shi
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we can factor out the $e^x$ and pull it outside the limit since it’s not being evaluated: $e^x\cdot \lim_{h\rightarrow 0} \frac{e^h-1}{h}$, the limit approaches 1 so the derivative of $e^x$ is just $e^x$
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You can factor $\frac{1}{2^k}$ from the second and third term.
Hum more like $1 - \frac{1}{2^k} \left(1 - \frac{1}{2}\right)$
Azyrashacorki
Well you can evaluate what is in the parentheses quite easily. You should be left with something already simpler than what you started with
Yes
Ava
$1 - \frac{1}{2^{k+1}} = \frac{2^{k+1}}{2^{k+1}} - \frac{1}{2^{k+1}} = \frac{2^{k+1} - 1}{2^{k+1}}$
Azyrashacorki
a/a = 1
coconut / coconut = 1
So long as a or coconut isn't 0
Yeah it's probably not necessary to go the step further from the app
There's a minus sign because we're taking -1/2^k out of the two terms
And the rightmost term was meant to be positive
$- \frac{1}{2^k} + \frac{1}{2^{k+1}} = -\frac{1}{2^k} + \frac{1}{2^k}\cdot \frac{1}{2} = \frac{1}{2^k} \left(-1 + \frac{1}{2}\right)$
Well here I took -1/2^k as a factor.
But you can take 1/2^k as a factor doesn't matter
Azyrashacorki
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