#help-0
1 messages · Page 15 of 1
No you don’t do that. Factoring out a 1/2 would give you .5(4s/(s^2-1))
You would factor out a 2
You factor out a 2…
Because 2 is a multiple of that fraction
Why wouldn’t you just use first principals on the original fraction?
That’s what i did lol
Then the person
Told me change the fractions
Ignore last line tho
It’s wrong i think haha
Basically i got until there
Also 1/(s^2-1) isn’t 1/s+1 + 1/s-1 ???
That’s completely wrong ??
Wait I’m having an aneurysm
I fucking hate first principals
Same
what is first principal
I’m giving up its time for bed gn
Gun
Jelly why are you here asking that
It’s the definition of a derivative
Ye
oh i got it
Haha help me OwO I’m dying
i think it's a bit messy to calculate the original fraction
so i wrote s/s^-1 to be 1/2( 1/s-1+1/s+1 )
Mhm
and the 2 fractions are easier to calculate, i can show you the first one
Okie sure
@gritty verge Has your question been resolved?
Ooh
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Hi, just a question. I can use the factoring by grouping method for a cubic polynomial only if the first two coefficients have the same ratio as the last 2 coefficients, right?
@covert gorge Has your question been resolved?
<@&286206848099549185>
@covert gorge Has your question been resolved?
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how the heck am i susspoed to graph xe^-x
Consider derivative and second derivative of xe^-x
yeh
So it increases on [0,1], decreases on [1,inf). Concave down on [0,2], concave up on [2,inf)
Those are enough to sketch
how did u get those values
This
how do i get those point from it?
Are you just looking for a graphing calculator?
I said derivative, not integral
,w derive xe^-x
how do u tell it increases from 0,1
Check your textbook
the roots are only giving you the stantionary points
im confused on how u r getting these domains
I need help
.
I’m a 13 year old and don’t quite u detestando a questsion
How does 8 square root turn into 2 in the power of
ok
8 = 2^3
2^3
what is square root?
bro get the heck outta here!!!!
u already wrote it
my channel
I still don’t get it 💀
How do I open it
just type ur question there
,w derive -e^-x(x-1)
ok heres the second derivative
how did you know it concaves down from 0,2
ik what inflecction points are
but im unsure how you concluded on it to be concaved down from 0,2
@oak perch if ur not going to show me how to do it at least tell me, so i dont waste my time watining for an answer
telling me to review my textbook isnt helping
Okay.I won’t, those are elementary facts, definitely in any textbook
@tidal zealot Has your question been resolved?
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In the second row in the table where, how is the probability for X=2 and Y= 1 1/18? What is the second case (2,1) is the first case. (1,2) comes to mind but it doesn't satisfy X>=Y.
it doesn't say that X refers to the same dice every time. Instead, I think it refers to the bigger number rolled
then how can we have all those zeros there then?
X is never less than Y ig
the probability that the bigger number is 2 and the smaller number is 5 is 0
guys I am really really slow when it comes to probability. but doesn't (1,2) mean exactly what layla said?
P(X = 1 and Y = 2) looks like 0 by the table
you can roll either a 1 and 2, or a 2 and 1. Both rolls correspond to X=2, Y=1
np 💜
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does this make sense to you? im not 100% sure if i got this question right
maybe you should specify that the marbles are distinct, and replace "3 or 4" with "at least 3" for elegance (though the latter is less obligatory)
okay so I will word it like "James has 4 marbles. In how many ways can at least 3 marbles be picked. Assume each marble is distinct"
thanks for helpin' me :))
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i have this
and i have to prove that this
have integers numbers and i really don't know how they got the answer
like they get 2^13*A(log base 2 of 16)
it would probably be a good idea to multiply A(a)*A(b) and see if find a pattern
A(a)*A(b) = 2A(ab)
good. so what happens if you repeat that?
4A(abc)
and again?
8A(abcd) i think
and again?
oh so 2^13 is the number of of how much it multiplies
the exponent is the number, yeah
and the logarithm, how do they get log in base 2 of 16? do they transform each of them in base 2?
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"If a population grows at a constant rate of 2.8% per year, then what percent will it grow over the next 10 years?"
How do I solve for that
ok so
lets start with an easy question
what will be the percentage of the population next year
5.6
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Hey,
Given G=(V,E) a directed Graph. Is there any way to calculate the maximum number of strongly connected components, only based on n nodes and e edges?
I probably won't be able to help but does that mean calculate the maximum number of strongly connected components among all directed graphs with n nodes and e edges?
well if you want the max then I assume the best would be to pair up two vertices until you have no edges or vertices left
@strong dome Has your question been resolved?
yes, but as as in possible upper bound, assuming you are given n nodes and e edges
yes that's good way to approach it if we build it through the process
I was thinking maybe there is some general proof or formula for it or like anything known that I don't know, which could help
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neither the x coordinate nor the y coordinate of point C equals 180
point C corresponds to an angle of 180°
what’s the difference
well the correspondence between points and angles is specific to the unit circle as drawn here
while coordinates are by and large independent of what happens to be drawn on the plane
(aside from the axes which define them, of course)
How was I supposed to know C was the right answer
@next flax Has your question been resolved?
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say A is a vector space and B is a subvector space of A, are the vectors of the base of B also part of the base of A? so can we add more "vectors" to the base of B to create a basis for A?
i'm trying to understand the proof of the rank nullity theorem but i don't understand this piece here
yeah
You can always extend a basis of a subspace to a basis of the whole space
you can complete the basis of B to create a basis of A
- We know that the kernel is a subspace of V, so we get it's base
- We add vectors to this base so that it becomes a base of V
- ?
it might be using some definition which i forgot
3 is just definition of T(B)
The image of a map is just the space spanned by the image of the vectors in a basis
You take B, apply T to all the vectors and their span is the image of T
But then loads of those vectors are actually in the kernel of T so they're not contributing to the span at all bc they get sent to zero
ok so the remaining vectors will be the ones that we added
Yeah. Zorn’s lemma
which being part of a basis are linearly independent so the dimension is the same as the one written there, aka n - k
but why do we have to go though this intermediate step of proving that it's independent, we already knew it from it being part of a base
We knew that the w_i were part of a base for V
oh wait it's so that we can split it into different pieces that can be used to finish the proof
It's not immediately obvious that this means the T(w_i) are linearly independent
They prove this
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Consider the random variable X with density f(x) = (1/6)x where 2 <= x <= 4.
Find Expected value E[X].
What i did: calculated the integral from 2 to 4 and got the answer 1.
Answer says: 56/18
Is my answer wrong wrong or is the book wrong?
@urban flint Has your question been resolved?
the integral just gives the area under the density curve
the area is always 1
ok after some google i found this:
expected value=integral of x*f(x) from 2 to 4
$\int_{2}^{4} x\cdot f(x) dx = \int_{2}^{4} \frac{1}{6}x^2 dx$
~Martin
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Just find how many ways you can select the committee without restrictions
and then just subtract the number of ways you can choose 4 students or 4 teachers
which one is 10!
arrangement doesnt matter bro
ok
how many ways you can choose the committee if you can only choose either 4 students or 4 teachers
5C1 x 5C3 + 5C2 x 5C2 + 5C3 x 5C
not gonna lie im confused
this is like my last 2 braincells making an attempt
ok so first of all
you can try to find the number of ways you can pick 4 students
there is 5 students, pick 4
5C4
and then you can find the number of ways you can pick 4 teachers
there is 5 teachers, pick 4
5C4
do you understand this?
5C4 x 5C4
no
i understand thus far yes
5C4 is the number of ways you can pick 4 students/teachers
so.. without restriction you have 10C4 right?
you just subtract it
10C4 - 5C4 - 5C4
that is the number of cases where there is at least 1 student/teacher
because you removed the cases where there is no student/teacher (- 5C4 - 5C4)
bro
10c4 - 5c4 - 5c4
or N combinations of K
10c4 is 210
yes
so you just put it over the number of cases without restiction
200/210 = 20/21
which is the answer here
20/21
yeah
ty
can you check this one for me
i dont think its correct since the number is so large
you dont multiply, you add for a
because it's number of cases
not probability (because you usually multiply in probability)
yes
should be
cool
so this is just like 5C4 but you also count the arrangemnts
it's called permutation
yup
yeah, i think it's correct
for a
ok imma change it back
yeah my bad
you good dw cuh
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Help needed
<@&286206848099549185>
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sowy
What have you tried to do?
Umm Thinking that I tried to to 13(1-cos^2x)/2+cosx + cosx = 2
Okay?
didn't understood
multiply 2+cosx first
to which?
everything
okay?
You want to get rid of the denominator, so you multiply everything by 2+cos(x)
Then you want to change sin²(x) into an expression with cos instead, so you only remain with cosines and you basically have a quadratic equation to solve
okay so now
Akash Kumar
Like this?
no
okay so how?
$\frac{(13sin^2x)(2+cosx)}{(2+cosx)}+cosx(2+cosx)=2(2+cosx)$
Like this? or any changes?
u didnt multiply 2+cosx on the right side
Akash Kumar
any changes?
okay now
clear everything up and you will get a quad
${(13sin^2x)+cosx(2+cosx)=2(2+cosx)$
Akash Kumar
Like this Hope so?
no
I did same
Akash Kumar
Akash Kumar
yes
And for the sake of simplicity you can do u = cos(x) if that helps you solve it.
Okay Thanks for the Tip
wait I got as
$9-12cos^2x=0$
Akash Kumar
is it right Hope so?
@alpine sable sorry for Ping
okay I get it
wait I forgot F*ck
how did you get 8.66
nah ur tryna get x
This is more or less what I meant.
wait no
bruh ~ _ ~
i thought you were saying that the answer was pi/2 and pi
I'm saying in radians 😂
you have to get the answer now
It's pi/6
and?
-pi/6
@slow wasp -pi/6 would imply 11pi/6, which isn't what you want to have.
sorry to keep negavtive symbol
Yea
Basically you're trying to solve the two cases separately.
First solve cos(x) = sqrt(3)/2
You get pi/6, yeah?
okay so for 12 should I divide by 3 & 4 or 6 & 2 or 1 & 12?
Wdym
I'm making A^2-B^2 into (A+B) & (A-B)
Yeah sure.
yup
umm which is suitable BTW?
Doesn't change it at all. You can divide by anything you'd like. But I guess 12 should be good.
But I don't see the point, you already did that.
When you got +-sqrt(3)/2
wait It's in 9-12cos^2x form
u already got alpha
we need beta
alpha=pi/6
yes
now get beta
beta it will be -pi/4 or smtng?
Use this
how?
plug in alpha
That's right.
great
Okay so the angle are 150 & 30
@alpine sable BTW if u don't mind could you show me the working
i didnt do any working lmao
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I have no idea how to even start
we know that the product of these matrices is the identity matrix
That's enough equations
yes
okay that was easy what the
thank you guys very much
I was so confused
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Not as many x^2
i combined 3x^2 with -x^2
Should be +2x^2
ohhh mb
h should be the derived function of f
but it dosent seem to be correct
i used the partial rule thing
f'(t) X g(t) + f(t) X g'(t)
did i do something wrong
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<@&286206848099549185>
what is r?
It's the position vector for every point on the surface.
@harsh nimbus Has your question been resolved?
ok
i am confused on how to parametrize this
is it 4sin(phi)cos(theta)i+4sin(phi)sin(theta)i+4cos(phi)k
Yes.
$\vec{r} (\theta, \phi) = \langle 4\sin \phi \cos \theta, 4\sin \phi \sin \theta, 4\cos \phi \rangle$.
stabulo
You can now calculate the cross product after computing the required partial derivatives.
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hey guys i feel lost right now trying to figure out this problem
i have no clue of what to do
i am thinking ouf using sigma but i have never learned it so i dont know what to do
plz help
7000
how about the second?
7000 x 1.65
and the third?
7000 x 1.65 x 1.65
how about the fourth 
youre on the right track but simplification error
$7000 \cdot (n-1)1.65 = 7000 \cdot \underbrace{1.65+\dots+1.65}_\text{n-1 many}$
jan Niku
but you want $7000 \cdot \underbrace{1.65 \cdot \dots \cdot 1.65}_\text{n-1 many}$
jan Niku
what can you use for repeated multiplication?
Exponent?

So 7000 x 1.65^(n-1)
is it true in the first year?
so youre almost done with A 
you should write a nicer definition IMO just to be sure its clear to yourself since u gotta use it a few more times
something like $f(n) = ...$ is the number of lionfish after $n$ years
or whatever
jan Niku
as long as you can show all the work
ok perfect
part b is just plugging it in
f(6) = 7000 x (1.65^(6-1))
= 85609
and is part c just f(n)=7000(1.65^(n-1)) - 1300(n-1)
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Hello, how do you prove it for power 3 please ?
as far as i can go i just found f g f g = I
~Martin
$$f^2=I$$
$$f \circ f=I$$
$$\implies f=f^-1$$
~Martin
so we know that f is it's own inverse
the same goes for g
$$(f \circ g)^{-1}=g^{-1} \circ f^{-1}=g \circ f=f \circ g$$
~Martin
so we have proven that f.g is also an involution
saying that
$$(f\circ g)^3=I$$
implies that
$$(f\circ g)^2(f\circ g)=I(f\circ g)=(f\circ g)=I$$
~Martin
this would imply that $$f \circ g^-1$$
~Martin
which is not always true
which contradicts the statement
so i must have made a mistake
but i cannot find it D;
thanks anyway, power 2 was easy but power 3 is a mountain
ok i am pretty sure the statement is false
f g power 3 is not equal to identity ?
its difficult to prove something that isn't true 
serge lang is a great mathematician, you think he did it on purpose to ask to prove something false and being stuck because is impossible
?
$(f \circ g)^3 \iff f = g^-1$
isn't he known for trolling
so we just found 2 mappings from S to S which commute such that the statement is false
im not sure what the standard notation is so i explained mine
oh
also since f.f=I and g.g=I but f!=I and g!=I in general
I would expect (f.f)^n=I for all even n
the statement is true for even integer and false for odd integer i guess then
thanks you !
you're welcome
a:=2
define a as 2
is not like a = 2 ?
yeah but i like to use := since that's what i have been taught
i guess you can use both
if we say f.g=2=a
then someone could see that as
f.g=2 what happens to equal to a
what is the motivation behind it
but if we say 2=:a we say we define a as the result of f.g
i guess it looks cool as well
also if we say f.g=u then someone might ask "what is u? where did that come from?"
if we say f.g=:u or u:=f.g then it is clear that we just defined u so others don't get the impression they forgot some u a few lines before
@random mica Has your question been resolved?
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d
@inland vessel
well... this is interesting
.... yeah i dont have a question since im lost
okay
lets start from the beginning
with equivalence
and proposition
tell me
what is a proposition
A statement that can either be true or false
correct
its more than that
well you or eric framed it that way so i gone with that
So: "If Q is true then A is true, but if Q is false then A is false"
yes
that is an equivalence
so now example
a+c=b is equivalent to b-c =a
does that make sense?
@inland vessel
in a way
is it confusing
in a way it is
why is it confusing
okay
what else?
is this a formula?
p is the same as (a+c = b)
ik
but
is this a formula or a patterm for all configurations of statements that are if-then statements
this is the truth table for equivalence statments
ok now that's less confusing
equivalenve is the same as "if and only if"
it doesnt matter, different books write it differently
just stay consistent
thats the most importent
that's the confusing part
remember
with equivalence statements
you are checking the proposition
so is it true that, Q is true if and only if A is true
So im going back
"If x,y are integers, then x+y produces an integer"
this is true
this is an if then statement
"If x,y are integers, then x+y does not produce an integer" is false
that is an impication
wot
not an equivalence
wait
implication is not the same thing as equivalence
equivalence is if and only if
oh
ok
So for example:
"If x,y are integers, then x+y does not produce an integer" is an implication, because it has if-then.
oh
nvm that's a.... equivilence (the table)
so you are not completely correct with how you interpret it
listen to me
in the first row it is true that x,y are integers
thats the first row and first column
in the second column
it is true that x+y is an integer
and in the last column
is it possible from this information that the first two columns are equivalent
the answer is true
Should I write
"x,y are not integers if x+y are integers" impossible
what is impossible?
"x,y are not integers if x+y are integers"
no
okay listen
what is impossible is that(if x,y are integers then x+y is an integer)
yes but that statement is impossible if x,y are not integers and x+y is an integer
(if and x,y are integers only if x+y is an integer) is impossible if (x,y are not integers and x+y is an integer)
does that make sense?
So
(x,y are not integers if x+y is an integer)
This is your proposition? or just the equvilence
no
you can write the proposition in two ways
(if and x,y are integers only if x+y is an integer) is your proposition?
or is that rather, your statement
itself
( x+y is an integer if and only if x,y are integers?) or (is x,y are integers equivalent to that x+y is an integer)
ye
ye its the statement
there i fixed it
(x+y is an integer if and only x,y are integers)
(x+y is an integer if and only x,y are integers) is impossible.
well this is more and more confusing
my god
we dont know whether the proposition is impossible or possible
(x+y is an integer if and only x,y are integers)
and we find out
by doing the truth table
ok
so what's after
okay
you take every possiblitity
that x,y are integers or not
ect
and see if it corresponds to an equivalence
does that make sense?
(x+y is an integer if and only x,y are integers) -- statement
(x,y are integers and x+y is integer) -- Possible?
in this case ^
lol
second is wrong
wat
there should not be "then"
just "x,y are integers and x+y is an integer"
not "then"
yes now, what is possible?
oh...
(x,y are integers and x+y is integer) -- These conditions are possible if (x+y is an integer if and only x,y are integers).?
idk
in that case
(x,y are integers and x+y is integer) <-- this is possible
no
well then idk then
in that case the proposition is possible
so (x+y is an integer if and only if x,y are integers)
this is possible then
Proposition: (x+y is an integer if and only x,y are integers)
The proposition is possible if (x+y is an integer if and only if x,y are integers)
The proposition is not possible if (x+y is an integer if and only x,y are not integers)
no if (x,y are integers and x+y is an integer) then the proposition is possible, the proposition is "(x+y is an integer if and only if x,y are integers)"
lets make it more abstract
A is equivalent to B
this is the proposition
okay?
So:
(x+y is an integer if x,y are integers) is our proposition
ok?
yes
now if A is true and B is true, is it then possible for the proposition to be true?
sure? but im not sure if i do particularly understand the example
A is just something that can either be true or false, B is also something that can be true or false
and the equivalence says that if A is true then B must also be true and if A is false then B must also be false
yes
woah woah woah
then
If A is true then B is also true. Is a statement.
Is our equvilence
no the proposition is the equivalence
now im extreamly confused
why
"and the equivalence says that if A is true then B must also be true and if A is false then B must also be false"
you're saying "if" now
thats correct
no
ok, so then i dont know
A is true if and only if B is true
so now.
A is true and only if B is true
- If A is true and B is true, then our proposition is possible.
- If A is true and B is not true, then our proposition is not possible.
3.If A is false and B is true, then our proposition is not possible.
4.If A is false and B is false, then our proposition is possible.
we look at all possibilities
correct
good job
where
A is true and only if B is true -- proposition
- If A is true and B is true, then our proposition is possible.
- If A is true and B is not true, then our proposition is not possible.
3.If A is false and B is true, then our proposition is not possible.
4.If A is false and B is false, then our proposition is possible
so there is a pattern
yes?
yes
ok
but its the same concept
proposition and then condition
but this time our proposition must be an implication? @marble saffron
So therefore:
also
?
just to add
if A is true then B is true, and if B is true then A is true, then A and B are equivalent
so an equivalence is an implication in both directions
Proposition: If A is true then B is true
A is true and B is true, then our proposition is possible
A is true and B is false, then our proposition is impossible
A is false and B is true then our proposition is possible.
A is false and B is false then our proposition is possible.
for implication
yes
Applying patterns:
If x,y are integers then x+y become integers
Conditions:
- x,y are integers and x+y are integers , then our proposition is possible.
2.x,y are integers and x+y are not integers, then our proposition is impossible. - x,y are not integers and x+y are integers, then our proposition is possible
- x,y are not integers and x+y are not integers, then our proposition is possible
?
lets go back to A and B for a second
?
lets imagine there are 2 propositions
if A then B, and also if B then A
if both of these are true
then that is the same as saying
A if and only if B
2 implications in both directions is the same as an equivalence
oki
alright
which one?
you should understand them
just continue reading the book i guess
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Anne plans to retire at 65, and wants a perpetual monthly income of $4000 from then on. Knowing that market fluctuations happen, she invested in a fund that pays the Inflation Index + 6% per year to guarantee she won’t lose money with the devaluation of the currency in relation to inflation.
Anne calculates how much the 6% coupon is equivalent to monthly and applies the perpetuity formula, thus obtaining an estimate for the amount she needs to have saved to reach her goal. This amount will be approximately:
a) 1 million
b) 900 thousand
c) 820 thousand
d) 740 thousand
Ok so basically I’m having a tough time figuring out how I should approach this question even though it literally explains to me how lol. Can someone please enlighten me? I guess I should figure out which one of those amounts Anne should have in order to have a perpetual income of $4000/mo? But how?
@carmine sonnet Has your question been resolved?
@carmine sonnet Has your question been resolved?
@carmine sonnet Has your question been resolved?
<@&286206848099549185>
Basically I am supposed to make "4K" into the annual amount
so 48k
and make the 6% into the decimals
So
PV = C / R
48,000 / 0.06 = 800,000
I was doing it wrong because I was doing 4000/6
omg
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random question, but is there any way to calculate the tangents lines of a circle or ellipse without using calc? i know you can calculate the tangent line of a circle without calc but only if you are given a point on the circle and not anywhere else.
