#help-17
1 messages Ā· Page 230 of 1
Oh
but cant you just leave it as
A scalar and a vector
Or is that just impossible
It's undefined
If you add a scalar to a vector its undef?
yes
scalar multiplication is defined
photomath says its undefined because of rows and columns
but i dont get it
because it doesnt treat it as a dot product
it treats it like a product of two matrices
and you cannot multiply a 3 by 1 matrix with itself
so wait is the answer -1(1 2)
ye
you have to have as many columns as the other one has rows
for matrix multiplication to be defined
So for a 3 x 1 matrix you need a 1 x n matrix
what does l and m mean
can u show me an example
the 1st letter denotes the amount of rows, the second columns
l x m
l rows and m columns
m x n
m rows and n columns
ah
so wait the lets say if it isnt in the same dimensions, the dot product wont work
is that what u mean
the dot product is only for vectors (aka matriced with only one column defined)
but that is different from actual matrix multiplication
bacc
First one is defined by matrix multiplication because we have the 3 x 1 and 1 x 3
So the result is a 3 x 3 matrix
ok so if the second is a dot product i know how to do it
nvm ima look up online how to solve matrix multipli
okay ty
essentially, you multiply each row with each column, respectively
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can you express the numerator as a sum
Aren't you going to sleepš§
What does the top look like?
You should get a nice simplification
I get it, thx
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Just type .close next time
Yeah, both works
Sometimes I'm just too lazy to type close š
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I'm having trouble with an arithmetic sequence problem. The sequence a_n is defined by a_1 = 1/2 and
a_n = a_{n - 1}^2 + a_{n - 1} for all n greater than or equal to 2.
The goal is to prove that
1/(a_1 + 1) + 1/(a_2 + 1) + ... + 1(a_k + 1) < 2 for all k greater than or equal to 1.
So far, I've gotten to
1/(a_{n - 1}) - 1/(a_n) = 1/(a_{n - 1} + 1). Can somebody tell me how to substitute this into the original sum? This might be very straightforward but my brain isn't working very quickly right now...
this is hard to read
im sorry i genuinely have no idea how to make it more readable
picture?
I'll add what I've done so far:
This is where I am right now
I know it gives me a substitution I can put into the original sum, but i'm not sure how to do that
this is fine
the last equation you have is what's important as you've noticed
using it, you can consider what 1/(a1 + 1) + 1/(a2 + 1) + .... + 1/(ak + 1) would be
I know its just really not coming to me right now.. like I can see that it has the same form as the terms in the sum so I can probably substitute it somewhere but I can't think of it for some reason,,,
like I know 1/(a_k + 1) = 1/a_(k-1) - 1/a_(n) and then 1/(a_(k-1) + 1) = 1/a_(k-2) - 1/a_(k-1) and so on but i dont know how to show that leading to an answer?
Could you maybe give me a hint if you know? It's probably obvious but I'm unable to see how i can use 1/(a_n + 1) = 1/a_(n-1) - 1/a_(n)
You should learn latex or just write it and take a picture
you deleted the question š
replace 1/(a1 + 1) with 1/a1 - 1/a2 and etc
Everything I wrote was originally in latex, but I didn't know it worked for discord?
$1/a_(n-1)$
riemann
Yea no
$\frac{1}{a_{n-1}}$
night night
oh wait yay

š
im sorry that was really obvious... i
will work on that and see if I finish
@ivory fulcrum Has your question been resolved?
@ivory fulcrum Has your question been resolved?
OK so I was able to find the terms and a telescoping series in the sum, but I still don't know if this shows that the sum will always be less than 2?
This is what I've done
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if f is continuous on [a, b], then S = {x in [a, b] : f(x) >= 0} can be seen as an at most countable reunion of intervals? How to prove that
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Can someone help me with simpson rule (numerical method) that approximates integrals
How is the formula derived from the parabola equation based on 3 points?
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was learning integration by partial fraction. when i form partial fractions. just for simplicity sake lets say $\frac{2x+1}{(x+2)(x+3)} = \frac{A}{x+3} + \frac{B}{x+3}$ why can I put any values of x? to find A and B?
Matchstick
my teacher said something about it becoming an identity
but i cannot fathom what difference that could possibly make
because you're turning that original expression into another form, but you can go back to the original by algebraic manipulation
how is an equation any different in that respect
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hello is this available?
is there anyone here?
help me with this question
i have the solution for this question but i dont understand it
<@&286206848099549185>
share the solution.
@toxic river
and the ans is option B
<@&286206848099549185>
where are the helpers :((
@vast shale
i have the solution but i dont understand it
and i believe you wont too
there was no other information before this?
no
you need to find the value of that expression
do you understand the first half of this?
no, i understand the second half
that's about where i'm at as well
after they took log
idk how you were supposed to know to do all that in the first half
if you got any other solution
to begin with
this is high school level problem
i am thinking of finding a different method
like either writing a general term then take summation and then use integral sum of limits that way
where n tends to infinity
@pallid forge can you help me with the general term
if the powers are not visible
well the numerator you can find in the third line of the given solution
but i need to understand how i got to the third line
well you could work backwards i guess
can you explain the first two lines
recognize that the numerator is the derivative of the denominator
my guess is that they worked backwards originally to find the solution
and then for some reason presented it in a forward manner like it comes naturally to multiply three polynomials together and know the equivalent polynomial
thats not how you are supposed to make questions
from here
maybe try starting here
can you think of any other method?
do you understand the first two lines?
@pallid forge
can any other helper help me out
<@&286206848099549185>
š¦
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how did they get this
are you familiar with partial differentiation?
yeah
so the first equation is the partial differentiation of r(theta,phi) wrt theta. So you basically assume that phi is a constant while differetiating wrt theta
my calc 3 is very rusty i forgot what this is called
in the first term or r, 2sin(phi) would be constant and you then differentiate cos(theta)
yeah i can do that but idk why
ohhhhhh
nvm
it's just notation
was this called directional derivative?
what is this $\vec{r_{\theta}} \cross \vec{r_{\phi}}$ ?
ahtrader
are you familiar with cross product of vectors?
yeah
those two equations give you the vectors r(theta) and r(phi). now you apply cross product between those two vectors
yeah but why do i need it for the surface integral
srry i think im asking a dumb question
the surface element dS is given by magnitude of (r(theta)xr(phi))d(theta)d(phi)
so when you do zdS and substitute dS in terms of the parameterized form you would have to compute r(theta)xr(phi)
ofc not
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For combination and permutation, can anyone define what does it mean by order matter
if order matters then each arrangement is considered unique
for example you want to permute 2 numbers lets say 1 and 3
if order matters then (1,3) and (3,1) are both different arrangements
but if order doesnt matter then (1,3) and (3,1) are the same thing
So what type of question would be like tho
For both
What if you have like 6C5 and 6P5 what does that mean
P is for permutations
and C is for combinations
No I mean the orders
Permutation when order matters
Combination when order doesnt matter
Like so (12345) and (54321) are same thing for combination?
you can remember as "permutation is an ordered combination"

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[ \sum_{k \geq 0} a_k < \infty \iff \sum_{k \geq 0} \arcsin(a_k) < \infty ]
ananas
0 <= a_k < 1
I think it's true because sin(x) = x => x = arcsin(x)
for small x ofc
it's easy to prove it backwards since arcsin(x) >= x on [0, 1)
not sure about the forward direction
Is this a part of the problem? Coz otherwise it seems like a wrong conclusion to make
coz if sum of a_k is finite, so is the sum of 1000000000*a_k. So, I wouldnt arrive at this as a conclusion
I mean I get that a_k gotta be smaller than 1 for arcsin to exist but still, I feel like that has to be part of the problem
well at least eventually you have a_k < 1 anyway
and then wlog you can just look at the end of the series where that is true
well sin x <= x so you can use x <= arcsin(x) for one of the directions
similarly, arcsin(x) <= 2x so u can use that for the other direction
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would you agree with the following? or see any issues
why not submit and find out?
it doesn't tell me
it doesnāt tell you if you were correct
yeah
seems like a quiz/test to me
online quiz
yeah
<@&268886789983436800>
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cheating?
i already answered, i'm just making sure
it's already submitted btw
thatās not cheating?
well now you did
i'm just looking for feedback
wdym?
.reopen
ā
I was going to ban you for cheating, I'm not buying that it's necessarily submitted so you're not getting any feedback on it for now
As in, was this in the test you did, and you're checking after you've done it that the answers you gave were right?
Cheating is normally an instant ban, I'm timing you out for now so you can't post about that question while the test is still active and consider that a very close warning
@eternal glacier has been around for long enough
if itās already submitted they shouldnāt be able to have access to it or if they did they should know the answers..
it says "clear my choice"
yeah a bit surprising that someone with >40k messages hasnt heard about the no cheating rule.
š
^
but they submitted already
ššš
be fr
I'm being pretty lenient considering cheating and slurs are like the two things we're pretty insta ban happy on
No point continuing this now though, just don't ever do something like that again or you will be banned
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Pls help me with the exercise d) I can see in the graph that it is decreasing starting at the point f(0), but I donāt know how to write it in math terms
Like {f(0);to +infinite}?
you just write "in the interval (a, b)"
yep so thats just infinity instead
Or it has?
how would you define domain and range?
you mean exercises e and f?
oh nvm i thought you meant e
now i am on d
the point F is decreasing is 3 blocks up, so Y should be 3
and X should be 0
so interval is (0,3)
no
The question is asking on what interval the F is decreasing, to me it can be all of these infinite intervals
that is y coordinates
oh yes sorry
but it is saying "on what interval" rather than "on what intervals" so its talking about a single interval so what it could mean I think is when it is starting to decrease
and that only being the (0, 3) interval
You mean it is all are intervals after point (0;3)?
but I think it is one big interval
the 0,3?
0 is not included since the function is not decreasing at x=0
No 0;3 and 4;-1
Yes right
what do you mean 4;-1
It is the point the interval ends
This
1 second let me recheck the intervals defination
nah nvm
Yes i get it but why I put only x coordinates
the notation for intervals might be different for u
the interval is not open in the negative direction
that is to say 0 ius not included
Interval can be only 1 point i believe, and since in question it is saying interval rather than intervals, so it could be either only 1 interval or the question is wrong
(0;4] we write it like so
ok
the function assigns values of y and x to each other basically
like ur used to
f(x)
so if I put x=0 then it gives me y=3?
thatās why I should look for x coordinates?
erm
its askins u in which interval
that is between which 2 points
is f decreasing
that is, f(x)
so between which points x_0 and x_1 is f(x) decreasing
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mayer-vietorUs
WOW I DIDNT KNOW ITS CALLED THAT IN SCHOOL THEY TEACH LIKE IDENTITY 5 ETC ETC ITS ASS ACCUALLY
@grim lotus how do I make it into like being able to put in identity
Anyone?
wdym?
wdym? you just have to replace x with (a+b-x)
2 pi - x right
Sorry I am shit in Intigrals school kinda rushed it I got this practice sheet from school so like I am trying to learn from this
-sin?
yes
so now u have $\int_{0}^{2\pi}\frac{dx}{e^{-sinx}+1}$
Astar777
try to think what u can do here
I/ E^ -SIN X? LIKEIN THE BOTTOM
1/e^sinx* but yes
SORRY YES
$\int_{0}^{2\pi}\frac{dx}{\frac{1}{e^{sinx}}+1}$
Astar777
SO NOW WE FIND LCM AND AFTER LCM THE DENOM GOES UP WITH DX
Astar777
š WHATEVER THIS IS ITS A SKILL DAAAAM
its ez actually
what do we do now tho do we take SMT as t?
nah
sum the two integrals you have
it cam be simplified more?
sum your initial integral and this
Huh
if we let the initial integral be I, then 2I = [ the two values of I you have]
I = $\int_{0}^{2\pi}\frac{dx}{e^{sinx}+1}$ and I = $\int_{0}^{2\pi}\frac{e^{sinx}dx}{e^{sinx}+1}$
Astar777
sum these 2
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.reopen
Is there any way to check if you solved a constrained optimization correctly?
Yeah I already did that and it checks out. Just wanted to make sure there wasnāt something I was missing. Thanks!
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i dont understand what they did here
position function is just -4.9t^2 + vt + C
did they set v to 0
and our constant is 1900?
hey can i get help
Ask in one of the available channels, this one's taken
initial velocity is 0 cuz ur dropping it
height or distance is 1900 cuz thats how high ur dropping it from
guys help me
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bro leave
is 2+2=5
ah
<@&268886789983436800>
so because we're looking for t and we're only given that the height is 1900 we set v to 0
to find the initial time?
like thats whats going on here
Don't troll
ok
they used a kinematic eq
the third one here i believe
that looks overly complicated
its really not
its not pretty to look at. its a lot easier for me to go "oh just set v to 0 and find t"
i dunno how ur planning to solve this w/o the kinematics eq but ok
cuz thats literally what they used
typically initial
x_i or x_0 denotes initial value
in this case distance/position
so here x_0 (or y_0 is more fitting ig) is 1900 as thats ur initial height
ya they put 0 at the left side to work out how long itd take for it to hit the ground
i thought velocity was the change in y
the instant ur dropping it, its velocity is 0
yes the rate of change of displacement
for these kinds of qs its safe to assume when they say "drop" that v0 = 0
so the velocity picks up as it goes further down? and the velocity is 0 at the exact moment my hand lets go of the rock
idk physics isnt my strongsuit lol
yes thats right
okay then i get it
and ofc ur acceleration in the y-direction is plain old gravity
so just to reiterate, t is how long it takes to reach the bottom, v is the rate at which its falling, and s is the initial height
t is how long it takes to reach the bottom
not necessarily, its just a variable, here f(t) is a function of height wrt time
v is the rate at which its falling
rate of change of the height ya
s is the initial height
well s_0 is... s is something else
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i got 3x2 can anyone verify?
@silver python Has your question been resolved?
actually i got undefined because in the final step multiplying by p1 is not possible
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im confused
not of the problem but how to input it
the system stated that for b, -4/3, -3/2, and -5/3 were all incorrect
Have you tried doing the two point form of the equation of a straight line
$\frac{y_2 - y_1 }{x_2 - x_1}$ = $\frac{y - y_1 }{x - x_1}$
David
Identify y2,y1,x2,x1
1--3/3--2
ik the slope though
i need help with the addition part
cause rn my input is 4/5x+(-4/3)
in slope intercept form
David
Where x and y are just the usual variables
Replace y1 and x1 in here
And replace m in here too
$\frac{4}{5}$ = $\frac{y - 1}{x - 3}$
No
OH
David
Then cross multiply
-3y/-x
No
confused!
$\frac{a}{b}$ = $\frac{c}{d}$ $\implies$ ad=bc
David
-3y=-x
From here
4/5=-3y=-x
Yes now add 5 on both sides to make 5y on its own
(4x-7)/5=y
Good
4x/5-7/5=y
Yay
):
Looooool
sorry! two sided coin
cause now i am allowed to continue further into the course and NOT understand stuff even more š
RAHHHH
LEARNING
LETS GOOO
oh and question, do the teachers ever actually do their job of teaching in uni or is it usually just the students teaching themselves? @twin horizon
Well I think it depends on the uni
we're a research 1 university
so they pride themselves on self taught learning š„²
ugh but the people are SO nice and the campus is gorj
anyways THANK YOUUU
i will 1000% be back
intro to calc here we come
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how do I calculate the sum of the series $\sum_{n=1}^\infty \frac{x^{2n}}{n+1}$?
card
do you know power series of ln?
No
power series of 1/(1-x)?
@lethal heart Has your question been resolved?
<@&286206848099549185>
the power series of natural logarithm is the same as the taylor series
,w taylor series log(1+x)
I know It!
what you have is close
find something similar to this to make the expansion match yours
card
$n=1-m$
card
$n+1=m$
card
$\frac{1}{y}\cdot\sum_{y=1}^\infty \frac{y^m}{m}$
card
$\frac{1}{y}\cdot\ln(1-y)$
card
$\frac{1}{x^2}\cdot\ln(1-x^2)$
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help, i dont know where to start
do you know the definition of uncertainty
kind of
like its a percentage of something not working
its the wording of his question that confuses me
ah
im like probably disabled so go easy on me
well
5% of 90km/h is 4.5km/h
so is the range like 90 plus, minus 4.5km/h
so 85.5km/h to 94.5km/h?
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what would be the equation of this graph
first does it look like any type of graph you are familiar with?
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Does anyone know any textbook for garde 12 problems??
https://www.doubtnut.com/qna/103515
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DC--cqPgpSaU&psig=AOvVaw31Yw6amFWPi2Cj8wpA2uTq&ust=1726986855463000&source=images&cd=vfe&opi=89978449&ved=0CBcQjhxqFwoTCPDM_dS304gDFQAAAAAdAAAAABAl
The graph of quadratic polynomial f(x)=ax^2 + bx +c is shown below.Which of the following are correct ? |beta-alpha|>2
The graph of quadratic polynomial \( f(x)=a x^{2}+b x+c \) is shown below.\n\nWhich of the following is correct?( Where α and β are the...
Where can I find a book with this kind of problems?
if you really want some pain in the ass problems
which will get you prepared for jee mains
and concept problems
for advanced
by cenagge
cengage
but
YOU HAVE TO DO ALL OF THEM
sometimes questions seem too easy and you are likely to skip the problems
but don't
every problem matters
OK
but which textbook can be helpful?
you are preparing for jee right ?
Yes
ŲÆŲ§Ų“ Ų³ŁŲ§Ł Ų®ŲØ ŚŲ±Ų§ Ł Ų“Ś©ŁŲŖ ر٠ب٠ŚŲŖ Ų¬Ū Ł¾Ū ŲŖŪ ŁŁ ŪŲÆŪ
Ų§ŁŁŁŁ
I'd suggest you join some institutes' distance learning programs. They would provide you with lots of varied material for practice problems, which in my personal experience better curated and covers everything. And would be cheaper than getting multiple books for PCM.
I have learned everything well and I want to solve problems to practice more.
I would use PDF instead of buying paperbook so this won't make it expensive!
Back when I was prepping, I was offered free online material as a promo by some online company called embibe. idk if you heard of it, they werent great for advanced, but they had a ton of mains level problems
No idea how they are doing rn, but you can check them out
Or you can just browse amazon for which publishers have ebooks for jee prep
Thanks
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Stuck.
what is the area of one triangular surface?
It doesn't tell me
the only value i have is the surface area & the width
what surfaces are there
@winged urchin Has your question been resolved?
yes and what do we know about them
nothing
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it is messy, you are not required to find the actual solutions
you are asked to apply IVT
hmmmm, i need to find an interval first though
can i just try and plug in numbers to see?
at x = 2?
yes
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for Q19, I am able to solve (a), but i dont know how to do (b)
I am not really sure how to get started
what you can think, is how the series related to what u have proved
yeah it took out the odd terms
You see in (b), all the numbers are even numbers
thats where im stuck
replace n with 2n
u can rewrite the top in terms of summation (n^3)
the second can be thusly written as summ (2n)^3
oh
fill in the upper value of summation and change the formula appropriately that u found
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ā
hi maybe i am getting things wrong, but the answer is not correct 
it should be (2k)³ instead of
2 sum k³
Yes
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Hi I have a question regarding surjective, injective functions etc.:
Define
f: A --> B
g: B --> C
If g o f is injective, then prove that f is injective and that g is not injective
I have a hard time proving this and making it intuitive
are you missing a part?
imagine A, B, and C are all R (the real numbers)
and let f and g both be the identity function
then everything is injective
Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.
,rcw
does als...dan mean if...then?
why are there 4 parts
Yes
I will translate it
Let f: A --> B and g: B --> C be two functions. Prove or disprove:
(a) if g o f is injective then f is injective
(b) if g o f is injective then g is injective
The answer sheet tells me a is true, b is not true
But I don't understand why
ok wow your original question was way off
okay, b will be easier
because all you need to do is to find a counterexample
might be useful to draw diagrams of A, B, C, f, and g
So for (a) this was my thought proces:
g o f: (A --> C) (actually A --> B --> C)
We know that A --> C is injective st every element a e A resonates with an element c e C, but since this has to go between B this means that A -- B is injective, hence f is injective
Not sure if this makes sense I'm very new to proofs and pure math etc.
Like this is my 1st week
But the same logic did not apply to (b) so I got stuck
the way that I would do (a) is to show that if f(x) = f(y) then x = y
at least that's the way I would write it
as for b, the proof is very different: you just need a single counterexample
hint on this: you know things about g(f(ā¢))
(g o f)(x) = g(f(x)) and x e A, f(x) e B, g(f(x)) e C
g o f is injective s.t. g(f(x)) = g(f(y)) implies that f(x) = f(y)
If f was not injective, f(x) could not equal f(y) because one output cannot have two different inputs
This means x has to be equal to y and hence f is injective
Is that valid?
no wait this is circle logic I think
Lemme try again
g o f is injective, thus A --> C is injective. Hence:
for x e A there is only one g(f(x)) e C, and similarly for y e A there is only one g(f(y))
Let's say that g(f(x)) = g(f(y)). Since g o f is injective, this implies that the inputs have to be the same f(x) = f(y), and this also implies that x = y since they both give the same final output. Hence, f is injective
I think I got it now
Now (b)
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could someone explain the class equation with S3
the class equation is
in this case |Z(G)| is 0
and x1 would represent all orbits
so we just get 6?
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!done
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anyone know how to solve this
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<@&286206848099549185>
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if x = a / b, what is dx/da and dx/db?
if you differentiate x = a/b with respect to a, 1/b is a constant
so what do you think it should be
oh, so dx/da = 1/b then?
I forgot a lot of this from calculus
maybe product rule if I remember correctly? (it's been like a year since I done this)
x = a * (b^-1)
dx/da = 1 * (1/b) + a * (-1/(b^-2))
dx/da = 1/b - a/(b^2)
?
feels very wrong
yea prod rule
a*1/b
1/b differentiation is zero
so the second term
becomes zero
ohhh
just 1/b
yep
ok so dx/da = 1/b
yes
same use product rule(if you want)
or just take a*1/b
keep a outside the differentiation
because its a constant
differentiating wrt b so a is constant
x = a * 1/b
dx/db = 1 * 1/b + a * (-1 * / b^0)
differentiation of a is zero
so it should be 0*1/b
we are differentiating with respect to b, so a is constant here
and differentiation of a constant is zero
no
you are differentiating wrt b
so a is constant
keep it out of differentiation
and just differentiate 1/b
constant multiple rule
ohhhh
1/b = b^-1
-1 / b^0
-1
why b^0
see the power rule
Power rule? I forgot a lot š¦
and try again
ohhhh
ok
thank you
1/b = b^-1
-1 * (b^-2)
-1/(b^2)
Ok, that seems more correct?
yes
yes
ok, thank you!
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how do i check for which angles this equation is defined for?
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guten abend
Was sind deine Zweifel?
b
Kannst du mir die Ebene aus a) nennen?
ok soweit passt die a)
jetzt wollen wir im prinzip zwei parallele ebenen bestimmen die einen abstand von 21 haben
ist andere ebene parallel?
ja
weil sonst schneiden die sich sonst
dann gibts keinen abstand wirklich
Davon gibts 2 stück einmal von links und von rechts
bedeutet das, dass beide ebene gleiche normal vektor haben?
ja
achso
Du musst im Prinzip die neue Ebene parallel verschieben bis sie Abstand 21 haben
wie?
Dein Kreuzprodukt ist ja (6,-3,2)?
ja
ist d 31
nein
wir müssen normieren
Die eine Ebene lautet ja
6x-3y+2z=10
Die Norm ausrechnen
,calc sqrt(6^2+(-3)^2+2^2)
Result:
7
Teilen durch 7
10/7 is der Abstand zum Ursprung von der Ebene a)
Ja genau
6x-3y+2z=10
und
6x-3y+2z=d
d muss 10+21*7 oder 10-21*7 haben
Wir multiplizieren mit den Norm weil wir die Ebenengleichung nicht normiert haben
Das wƤre das gleiche wie wenn man alle normiert also durch 7 teilt und dann +-21 hinzufügt um den Abstand zum Ursprung um 21 Einheiten zu vergrƶĆern
Hier eine Veranschaulichung
na gut.
was sind die zweifel
ich habe es verstanden.
š„¹
wie kann ich den Winkel finden?
Markier mich bitte sonst lese ich das gar nicht ^^
ok
Schnitt mit der z-Achse impliziert einen Punkt der Form (0,0,z)
z=5
E : 6x-3y+2z=10
wie finde ich den winkel
das sieht bissel kacke aus
Im Prinzip kann man das mit dem Skalarprodukt ausrechnen
Also wir wissen aus der a) die Richtungsvektoren, die in der Ebene sind, wir kƶnnen einen nehmen, sagen wir (-4,-2,9)
Und dann einen Vektor der parallel zur z-Achse ist, also (0,0,1) z.B
cosA = (6|-3|2)*(0|0|1)/7
ok erklƤr
Result:
10.049875621121
Ich denke die 7 ist falsch, die falsche Norm
du willst die Norm von (-4,-2,9)
nicht von dem Normalvektor von vorhin
,w sqrt((-4)^2+(-2)^2+9^2)
Die Norm von (0,0,1) ist trivial
aber warum (-4|-2|9)
