#help-23
1 messages · Page 265 of 1
rewriting them in terms of a, b, c will doubtlessly be helpful
like this?
damn the quality
sure
now starting with this term
here's where you use the thing you were asked to use
that's the thing you were asked to use
you can't
it'd be helpful to rewrite this as b^2/a^2
that's what you're doing right now
okok
so now that ive done this
i rewrite a^2 as
b^2 + c^2?
which leaves you with?
b^2 / (b^2 + c^2)
do that with the other sides probably
what's "that"
rewrite them using this
well there is no a^2 on the other side
would it be helpful to use c^2 = a^2 - b^2
not really
then idk how to proceed
this is your current right side
yes
this is your current left side
$\frac{b^2}{b^2+c^2} \overset{?}{=} \frac{ \frac{b^2}{c^2}}{1 + \frac{b^2}{c^2}}$
Steakanator
for the rhs
let's make it a little clearer
now what can you do to the left side so that it looks the exact same as the right side?
what's "it"
numerator and denominator
precisely
im not sure tho
alright so if i do that
the only left to prove is the far right one?
seems like it
that works
then its done?
do you get the same thing everywhere?
yup
then what else is there to do?
nothing
nothing
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Try 00
Thank you bro
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ive been lost on this for a while and not sure what i did wrong
i understood its a linear differential equation
got the Integrating factor as x+1-ln(x+1)
but tryna integrate
e^-x * the IF
is a bit annoyin
and hwen i checked with an online calc
it did some wierd sutf
Can you show your work for the integrating factor?
If you put the ODE in the form $\frac{dy}{dx} + p(x)y = f(x)$, you should get the integrating factor as $e^{\int p(x) dx}$, so something went wrong trying to get it.
Azyrashacorki
@restive laurel Has your question been resolved?
@restive laurel The best explanation of linear differential equations on the internet:
https://tutorial.math.lamar.edu/classes/de/linear.aspx
In this section we solve linear first order differential equations, i.e. differential equations in the form y' + p(t) y = g(t). We give an in depth overview of the process used to solve this type of differential equation as well as a derivation of the formula needed for the integrating factor used in the solution process.
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Where did I make a mistake?
I just found the answer and i was wronggg
it may help NOT to expand immediately
yeah that's why i factored again 😭
oh dang
just expand out the numerator and note you'll have an extra factor of 'h' that will cancel
:3
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Because (0.75 + 0.25*0.75) != 1.
If I understand, you would want to compute a quarter of 35.36 to add that onto the total. The issue is that the actual value of Q is not 35.36, but 47.15.
Thus, a quarter of 35.36 does not correspond to a quarter of 47.15.
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Anyone know what is the name of this function? or at least what can I call it? I need to call it with something
f(1) = 1
f(2) = 1+2 = 3
f(3) = 1+2+3 = 6
f(4) = 1+2+3+4 = 10
f(5) = 1+2+3+4+5 = 15
f(6) = 1+2+3+4+5+6 = 21
:D
I need help with quadratic function. Its really a basic concept question but why is y=x^2 a parabola shap in the graph? Like why do we also get the negative side part as well? Why does it have to be symmetrical in the graph.
what
the shape is because of the function
wdym
the symmetry is cuz even function
or f(-x) = f(x)
ok if (-x) = f(x)
then the function is the same for both left and right of the y-axis
you only need to draw one of them since they basically the same
as such drawing f(x) also mean you have drawn f(-x)
I'm closing this
.close
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I'm having some problems with this proof. I get this far then I don't know what to do with this extra 1
So ln(1)=0
ye
Thanks
np
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so i have this expression that im stuck on:
64^4 :(2^2 * 4^2) - [(12^5 : 3^5) * 4]:16^2
i did some passages:
64^4:(8^2)^3 - [(4^5)*4]:16^2=
64^4 : 8^6 - 4^6 : 16^2
the problem is that im stuck here bc i dont understand what to do after,the solution of this should be 48(its writed on my book) but i dont know what to do
aaa yes!ur right sorry but i have adhd and i sometimes do wrongs on this
thank u now i understood
Keep going, its all good otherwise
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You speak English very well, considering your age
i’ve learned it since i was like 6,im abt to turn 16 and i have like a C1 level based on a test of cambridge that i did 2 years ago in my school haha
Wow nice!
Che classe fai?
fai conto che sono stata rimandata in matematica quest’anno ma sarei in 2 superiore
Ma tu sei il mod nel gruppo telegram help matematica/fisica/chimica?
Che superiori?
Sì haha
allora tecnico grafico,ma cambio scuola e a settembre vado a fare un professionale socio sanitario
Grande
Ah ok ok
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can some pls help😭😭
i dont think so
Like PR • QI
maybe properties of traingle will apply
Pythagore ?
nah
maybe the midpoint of PR is the circumcentre of triangle PQR?
nah mb it wont help
wait
i got it
find the slope of PR
and QS is perpendicular to PR
so u can find the slope of QS too
from there i think we can get the value of q through equation of straight line
@rough igloo
@rough igloo Has your question been resolved?
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What is binomial variable
Is it related to binomial theorem
binomial random variable? or something else
@west hedge Has your question been resolved?
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Hey guys, I'm in a discrete math class and I'm being asked this and I have no idea how to solve this or figure out how to. Could anyone help me?
Are you familar w/ the process of re-indexing a sum?
That's what this question is asking you to do
The lectures didn't cover how to do that
o
So I'm not sure how to
The idea is that $$\sum^{k}{n=1} a_n=\sum^{k+r}{n=r+1} a_{n-r}$$
Civil Service Pigeon
Civil Service Pigeon
and the sum on the right is $\sum^{4}{n=3} a{n-3}=a_{3-2}+a_{4-2}=a_1 +a_2$
Civil Service Pigeon
In essence, the idea is that you're just "shifting" all the terms by some amount
and adjusting the bounds of the sum accordingly
Ohhhhhkay
(btw, r can be positive or negative here, as long as the bounds still make sense)
ex. we could've taken r to be -1 as well

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Could anyone help me with this Integration by Substitution problem? It has something to do with filling in the integral as f(u)du, but I can't figure out how to handle it when the actual du isn't the same as the du actually there in the function
in the top left is the initial problem, and in the top right is the rule I'm trying to apply to it
I'd just sub $u=\frac{1}{\theta}$
Civil Service Pigeon
It helps to build intuition for this if you rewrite the fractions using negative exponents
I did do that, with integral $theta^(-2)cos(theta^(-1))$
I did not format that right
alright, thank you
but so yeah, doing that, I saw that the thing outside the cos was the derivative of the thing inside the cos
so then I figured cos theta ^-1 was my u
I think part of why I'm struggling is because a lot of the stuff here is kind of arbitrary. Like I can't really think of a mathematically provable reason as to why I should pick what as my f(u) and du for any given problem, and then I really don't know what to do after I actually calculate the du from my f(u)
By making u just theta^-1 I was able to make this. I still don't know what to actually do next though
I gotta head off soon, but recall that $$\frac{d}{dx} \sin(x)=\cos(x)$$
Civil Service Pigeon
right, then doing it again, cos becomes -sin
you're right, thank you for that
I think I need to make what I have in the integral into f(u)du, so that then I can take whatever if my f(u) in that statement and integrate it. But right now the u is stuck in that cosine, and I don't know how to get it out
or if that's even when I need to do next
find the integral in terms of u and then substitute $u=\frac{1}{\theta}$ back in
Civil Service Pigeon
In general, when you integrate by substitution, find the integral in terms of the substituted variable and then replace the substituted variable with the original definition right at the end
ex. if you have an integral that's originally in terms of x and you then substitute a variable u, you would find the integral in terms of u and then substitute the definition for u in terms of x back in
so wait, does that mean that I can just integrate what I have now and then undo the substitutes?
even though it's not exactly f(u)du?
Rewrite it as $-\int \cos(u) \dd{u}$ if that makes you happy
Civil Service Pigeon
the contents of du is negative, does that mean I can jsut pull the negative sign out like that?
Is it still substitution if I'm picking pieces of the substitution out of it?
can the constants be additives or do they have to be multiples? Can you even get an additive inside an integral?
Like
Extracting a constant multiple is taking a number like 4 and pulling it out of the integral, but that's when the 4 is being multiplied with the rest of the function
What if the 4 was a constant being added inside the integral instead?
what if instead of kf(x)dx, you had (k+f(x))dx
could it still be factored out then?
probably not, I guess
You could do $k \int \left[1+\frac{f(x)}{k} \right] \dd{x}$ ig
Civil Service Pigeon
alright I rlly gotta go now
alright, sorry for keeping you so long
thank you for your help, I really appreciate it
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Ping me
integration is the reverse of differentiation
Ren integrate f''(x) then use the fact that f'(0)=2 to find the value of the constant (c) and repeat it again to find f(x) and use the fact that f(0) =2 to find the constant then you are done
You did right lol
For real?
yes this is the 4th option
938c2cc0dcc05f2b68c4287040cfcf71
@spiral saddle Has your question been resolved?
Draw the curve
how
e^-2.e^x
how do I draw the curves, I only have 1-2 minutes to solve this
See u know curve of e^x
You need the curves
Cz it will be ez to see
Which one is the answer
You know
e^x
im dont know
Ok see
Then check which curve is greater in that interval
The intersection point interval
U need higher-lower
,w plot e^x
,w plot e^x/2
how do I prove it
how to prove it
Can u see b/w intersection points which point is above or below
That is b/w 2 and 4
Check which curve is higher and which curve is lower b/w intersection points
@
i did a little table from 0 to 2 to 4
but this is not rigurous proof that g(x) > f(x)
Oh you need this
You should have told me
See let h(x)=g(x)-f(x)
See u know integral of e^(x/2) and e^(x-2) ?
let what
Then we diff. H(x)
definite integral or indefinite
definite
you are not indicating the upper and lower bounds
how did you know that g(x) > f(x) btw
I mean indefinite ofc*
I will tell
Wait wait let me recall
Yes got it
See let h(x)=g(x)-f(x)
Then diff w.r.t x
why g(x) - f(x)
And apply condition for increasing function that is h'(x)>0
I will explain
Apply
fair
,, h(x) = \int e^{\frac{x}{2}}dx - \int e^{x-2} dx
See
Can u tell texit functions
I will explain ezily
Tell me*
See I'm explain
what do u want to know, how to compile latex?
938c2cc0dcc05f2b68c4287040cfcf71
,w d/dx e^x
Ok got it
,w d/dx[h(x)=e^(x/2)-e^(x-2)]
see what
We took h(x) as e^x/2 - e^(x-2)
I took its derivative so it is h'(x) now if apply increasing function that is h'(x)>0 and find interval in which it is increasing
Find
w,
w,help
why do we care if its inscreasing
both f(x) and g(x) are increasing
but that doesnt prove that g(x) > f(x) 😭
te esta diciendo que como la derivada de la resta es positiva implica que la funcion es creciente
la h(x)
.-.
U know that if x1>x2
And function is increasing
Then f(x1)>f(x2)
We checking the same thing
We gonna find when h'(x)>0
And that the x where h(x) is equal to 0
We gonna compare
ahh
okay thats smart, thank u
so h(x) = g(x) - f(x)
and h'(x) > 0
mmm
,, h(x) = g(x) - f(x) \ h'(x) = \frac{e^{\frac{x}{2}}}{2} - e^{x-2}
938c2cc0dcc05f2b68c4287040cfcf71
can someone help I am still hardstuck
I drew the three graphs in geogebra and I want to know which area is important
blue is g(x) and green is f(x)
Unsure
.-.
I just know the intersection points are 0 2 4
in the drawing if we take the function h(x) = g(x) - f(x) in the interval [0,4] that we are taking and then we integrate, we are calculating this area
do you agree?
Suppose we are asked for this area
Fair fair
How do we remove the bottom area would be the question
1 to 6
Idk what i am doing with my life
I also don't know what I'm doing trying to help when my English is terrible and I have to use the translator
but i think que right answer is the a)
whats mean doe
if we see splits the first integral
your drawing is correct and mine is stupid
We can see it more safely
is it possible without drowing
drawing the curves*
Yes, this is just to gain intuition and continue with formal work
only with the drawings
@spiral saddle Has your question been resolved?
mmm
is about finding area between three curves

try sketching the functions if you haven't already, that would help you out alot
!occupied
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hello everyone, im a 9th grader and currently studying exponent, i need someone to explain to me about the answer and how to get to that answer. thank you :)
so 2^(n+3) = 2^n * 2^3 right?
ah yes
Yes
then you have 8*2^n + 2^n at the numerator
and you have 4*2^n - 2^n at the denominator right?
wait im confused, this is the b equation righht?
yes
'ah okay alr go on
so numerator is2^n(8+1)
and denominator is 2^n(4-1)
I guess you can do the rest
what have u done with part c
$\frac{3^{2024} - 3^{2022} + 16}{3^{2022}+2}$
Newt
hint :$$3^{2024} - 3^{2022} = 3^{2022}(3^2-1)$$
thhis is confusing
Newt
Newt
wheres the -1 comes from
Newt
oh yes
so in this case a = 3^2022
All easy from here
no wait
?
Newt
don't do calculation if it not simplified
ohhh
$\frac{8 \times (3^{2022} + 2)}{3^{2022}+2}$
Newt
so thhe answer its jus 8?
yeah
what is the process called in this
$3^{2022} \times 8 + 16= 8 \times (3^{2022} + 2)$
distribution
oh again
the $ab+ac=a(b+c)
i rlly dont understand distribution lol
Newt
did you get this one?
i get it
,w factors of 16
?
uh
im still kinda confused on the b equation bcs i dont understand fractions to muc
kinda confusing for me
huhh
@cyan vale is thhere a some kind of trick for doing distribution?
uh so where do i go from here?
please help me anyone
maybe replace 2^n with x?
so
order of operations
yes
I mean if you have 8 apples and if you add one more apple what do you get
do i convert it back again
9x
so
9x/3x?
yes
recheck
im confused
so i convert x into 2^n back again?
so the answers just 3?
yes
just simplified the fraction
same thing is done when you do $\frac{3}{6} = \frac{1}{2}$
MetuMortis
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thank you for hhelping me all
no problem
.close
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I mentions a step 2 but I dont think its important for this question
What does it mean by 'independent of'? It means like if we change the value of p we get a different answer for the volume of the body B right?
I know that no matter what value of p we pick the volume of body B will always be the same, but does that mean its independent? Or not independent?
Ok so it is independent?
if you found so
Hmm it said its not independent
What was wrong with my reasoning?
I know I wasnt wrong in my calculations, no matter what value I put for p I always get 2
Oh wait
I see what i did wrong
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Help me with 9th grade maths
Here to help
@bold phoenix Has your question been resolved?
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Hi
My teacher gave me both graphs of a function and its derivative but i am confused if I do the A to D for both of them or just the original function and the derivative is there just to help
@green mica Has your question been resolved?
<@&286206848099549185>
for the original function
the derivative is just helpful
Thanks
So are my answers correct
based on the original function i got these
if you could just verify
no
oh
you are to state the intervals of increase and decrease
you only have one
there is both a local maximum and local minimum
D looks right
What abt c
Ok let me redo this and come back
for concativity you need the derivative of the derivative right
but its just a line
Idk really
sure you do
f'' > 0 means concave up
f'' < 0 means concave down
so whats the derivative of a parabola look like
its a line
whats the line look like in this case?
youre given the equation of the parabola
Ok i will come back and answer this
yes
theyve given you a picture, though
we can just read off these intervals
where is the parabola greater than 0?
Positive infinity
I guess your form is fine
x < 0 is one of the places, yea
which others?
0 < x < 2 is where the function is decreasing
that leaves what else?
Wait i got it x < 0 and x > 2 is also increasing
jan Niku
at least, this is interval notation my teacher would like us to use
but maybe your class its not that important
you got the right answer either way

Ok I will see that is the rest right
Thank you
np
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what do I need to do to find the equation of a graph?
When x is 0 what is y from the graph
okay so it's always based on when x is zero?
No
But in this case that's all you need
okay so what will I need in other occasions?
The easiest method since you have answer choices and the graph, plug in a point that isn't an intercept and check it
Intercepts, gradients ,area it makes with x or y axis
okay
So for example, using the graph, you know that if you did x = 3, then you should result in 32, so plug in 3 into all the equations and see which results in 32
Not exactly
okay so what should I attempt to solve for when it pertains to these questions?
You can use the y intercept to eliminate choices
.
ah okay so to put the y intercept in an equation?
.
As I stated, you can use the y intercept to eliminate options but it's not going to necessarily give you the final answer
okay thanks!
Because the y intercept of that graph is (0, 4) so you can have choices like y = 4(2)^x or y = 4(4)^x or y = 4(8)^x which all has the same y intercept so would need to use another point along that graph to check
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I don't know where to start, I tried using derivatives but didn't really end up getting anything
I have no idea what to do now
Maybe same denominator -> l'Hopital would work? Have you tried something of the sort?
We're not supposed to use l'Hopital here
@bleak cove Has your question been resolved?
<@&286206848099549185>
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@balmy hearth
yea what do you need help in this?
Solving it, there's an indeterminate form and i have no idea how to remove it
do i evaluate the limit?
the limit is 1/2 btw but i have no idea how you get to that
Yeah sure please do
@bleak cove Has your question been resolved?
i would first use the limit law sheet i posted earlier to split each fraction into a collection of limits
yeah but you still get indeterminate forms
yep! but we can continue to split it down from there
i would start by combining the fractions
if you havent yet
the worst part is, with Hopital its really easy but without isnt
i tried doing that but it doesn't seem to work
Yeah but im not supposed to use it in this exercise unfortunately
Sure one sec
$test$
it gives $\frac{2^x - 1-x \ln(2)}{x \ln(2) (2^x -1)}$
crampter (prof univ AC)
Then i cant simplify anything
that shouldnt be multiplying on the bottom
wait nvm it should
next i would do the limits on the fraction
Yeah but they give 0/0
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how do i rationalise this denominator
What did you tried
@wind kite Has your question been resolved?
hi basically in rationalizing those kinds of fractions with radicals at the bottom u js have to multiply the numerator and denominator with that radical
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I'm trying to find the function P based on its given derivative function, but what I got out doesn't match the answer, and for the second part, my answer is off by exactly 1000. What did I do wrong?
this is the original problem
right, I figured out what I did wrong. When I was taking the 12000 out of my function when solving for C, I didn't divide C by 12000 at all. I figured I didn't have do, since C was an arbitrary value at the time, still not actually meaning anything
that was wrong though
whatever it is, my answers match now, and I'm going to bed cause my brain is fried
goodnight all
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Where did I mess up, the real asnwer is 1/6
I have not shown a lotta steps but I think you make still make out what I did
if you ever run into this problem in an exam, take each of the lines and put them into your calculator but replace every “x” by something like 0.0001
We aren't really allowed to use calculator in exams lol
But I'll try that right now because I am not in an exam
oh
Are all my steps correct? I used a lotta standard limits
Like lim x-> 0 sinx/x = 1 and lim x->0 (cosx-1)/x^2 = 1/2
Do you see where I made the mistake?
k
I don't understand a bit in the last part, your limit should be diverge given what you wrote
Which line?
like, where did 1/4x^2 go?
He combined it
I took lim x-> 0 common
oh ok
and put the - sign inside to make it cosx-1
Also limit is 1-cosx not cosx -1
Like the format
But still
Only changes the sign
and why is sin(sin(x))cos(x) = cos(x)
oh yeah sorry I forgot
He did a lot of intermediate steps
Divide and multiply by sin x
U should see why
I don't think that can be simplify to that
Yeah that was a bit rusehd on my part so I did not show the steps
It can
sin(sinx)/sinx
Is 1
Similarly sinx/x is 1
So residue is only cosx/x²
sin(sin(x))cos(x) < cos(x)
Yeah
amplitude that is
but isn't cos(x)/4x^2 diverge
like... I thought lim f(x)g(x) = lim f(x) lim g(x) only if both are finite
here one is not
that's why I say how did you get there
Agreed
The thing is
The way I'd solve this is by using Taylor series
That will give the answer
I would also use taylor if I see this
Yeah
so the simplification cannot be done there right?
yes... you have to have finite limit on both
because one will dominate anyway
if you have one that is infinite
why did I even combine then, I should have just let that one approach 0 lol
1/4x^2 approches 0 right?
as x->0
oh yeah
so it DNE
alright got it
my bad
I'll be more careful next time distributing limits
The teacher used cos(a) - cos(b) identity, then applied LH rule 2 times and then got the answer by simplifying
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hello
does anyone understand prefix tables and how to sum between two indexes
like if we turn abc into a prefix array [0, 1, 3, 6]
because a = 1, b = 2, c = 3, and prefix[1] = a, prefix[2] = a + b, prefix[3] = a + b + c
and we want to find the sum btween prefix 2 and 3
why TF are a lot of sources using prefix[3] - prefix[1] to do that
Wait could you give one of the sources?
yea
hold on that might be a bad example
i think this is just making the prefix array
i assume if left prefix index is 3, and right prefix index is 3, it should always be 0
why would we use the index of L-1
so you want to find prefix[2] + prefix[3] is the question?
the sum between them
the sum between two prefixes
all sources i find online in regard to this are saying we subtract 1 from the left prefix index
so what im asking right?
sum between prefix 2 and 3
i would imagine, but online sources seem to be implying that we would structure that like prefix[3] - prefix[1]
sum between index L and index R
but it's L-1
like im so confused rn
wait
im seeing this now
it's conflicting
but this makes more logical sense
im going to trust my gut and assume that a lot of online sources are incorrect
and likely relying on AI
because AI says the same incorrect thing every time
i dont understand
so you want to find sum between 2 and 3
which in this case L = 2 and R = 3, their indexes
its the same as taking the sum of the whole array, subtracted by the sum of the first two elements
sum of first two elements is the L-1 index of the prefix array
and sum of whole array is R index of prefix array
prefix 2 = 3?
oh yeah
but you'll be taking L-1 index of the prefix array
so in the original array, your L is 2
thus L-1 is 1, taking the [1] element of the prefix array
this would be L = 3 and R = 4 right
arrays count start from 0
ok maybe instead of using arrays we'll use equations
ok
wouldnt it be (0 + 1 + 2 + 3) - (0 + 1 + 2)
oh
i just want to find the difference between two prefixes
or the sum between them
which i think is the same thing
is the prefix here meaning the prefix array, or the original array
because prefix array is made from another array
