#help-0
1 messages · Page 23 of 1
^This is what I have down for #6.
If someone could help, I would greatly appreciate it.
<@&286206848099549185>
Yes?
I need someone to check my answers
Ok.
The notes look good, but I would provide reasoning on why the point would be so close to the asymptote, ok?
What would that reasoning be?
Prove that the point is getting very close to the asymptote, but does not lie on the asymptote. Try using a limit notation.
Where does the asymptote and the point lie?
The asymptote lies on 150, 450
Ok, and the point?
Let me check
Plus or minus infinity at the end, but yes.
Whenever I put that into my calculator, it says "Illegal Input"
Since there's also a y in f(x)
This symbol: ±
Still shows an error
No, it has to approach the the value of the asymptote, which is 150, not 3x.
My fault, it should approach 150, not infinity.
On the asymptote, y = ±∞
Yes.
Did I exceed your expectations?
You actually helped me learn.
Ok, so now that I included those two limits, is the question 100% correct?
Knowledge is ageless
Yes.
Were you responding "yes" to my question about correctness or...
Both.
You want me to use limit notation again?
Indeed.
For part b?
Yes.
You should.
I mean, is limit notation necessarily required though? I got the same fraction by just plugging in 20.
So you know that the point is 4 units above the asymptote, right?
Wdym?
Well, if the vertical distance of the asymptote is 0.00036, 4 plus that is 4.00036, which can be rounded to 4.
Correct?
Well, isn't the asymptote at y=4?
And the point is (20, 4.00037)
So can't I just do 4.00037 - 4 to determine the vertical distance?
So how is the point 4 units above the asymptote?
That would make it (20, 8)
You can, and I just did.
No?
Yes, it would.
Meet the requirements of this limit, and there you go.
Find a way to make the limit equal 4.
Yup.
So why would I need to write that again?
What does this prove?
Isn't my original answer acceptable?
This shows how it could be possible for the point to equal the asymptote.
Yes, it is acceptable, but this is for undrerstanding.
Not if you don't want to.
Could I just write both of them down and subtract the limit evaluations?
Sure.
Ok, so the question is absolutely correct now?
Exactly.
Ok, thanks
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if i move this cos2x to the left of the equality sign, does this eqn become homogenous differential eqn?
@past bloom Has your question been resolved?
no, if so, every equation is homogeneous
you can think of the functions only depend on x is the coefficient of y (y^0, y, y', y", etc.)
Then homogeneous means that a1y+a2y'+a3y"+...=0, where a1, a2, a3... is the coefficient function
A nice introduction to help you. 🙂
@past bloom Has your question been resolved?
thanks
.close
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properties of the discriminant
i.e. no x-intercepts
show what exactly
the work is right there
we can use that
the graph of y=x^2+kx+k+3
is an upwards facing parabola
to determine when that's always positive we can consider when that has no real solutions / no x-intercepts
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can anyone tell me how they got this answer, my brain is not working rn
like what did they do to get 3-x
OHHHHHH they added 1 + 2 and then x - 2x = -x
im so sorry ppl
thanks
.close
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Do you know the condition for parallel lines
nope
@opal merlin what does it mean for two lines to be parallel?
I know it’s the same slope
Oh ok
but what would I do for b?
Ok so you have y = 2x + b right
yup
And it passes through (-8,6)
right
So we should be able to plug in -8 for x and 6 for y, and the equation would be true
6 = 2(-8) + b
6 = -16 + b
22 = b
Hence b = 22
right
So final answer y = 2x + 22
appreciate it
🙂
Perpendicular is a bit tricky
It means they intersect at 90°
But what does this mean about their slopes?
Try to explore this a bit
right angle?
y=-1/3x+2
but how would I show my work
I found when you multiply the slope of two perpendicular lines you get -1
how does that check out?
Fantastic
Yes
If the slope of the first line is m, the slope of the perpendicular line is -1/m
So yep it’s -1/3
Wait you mean the b in y = (-1/3)x + b right
yeah
Yeah same thing, you can just plug in the given point
might’ve been confused on how I worded it
alright
just checking
-1=(-1/3)(4)+b
I want to make sure I have the right equation
Yep nice
For problem d would it just be y=-5
and for problem e would it just be -2
can anyone confirm this?
can you post original photo again
.
alright
can you see a value that never changes in this function?
yeah that’s what I figured
the x value never changes
For d
yup
what is something I’d write
since they gave you a point
they told u its vertical
once you know its vertical, you just write x = ?
for e
and e is the exact same thing, except that you don't do the method we did for x, you do it for y
can’t it go from negative to positive tho
y= ? is a horizontal line
the y never changes
don't touch the x in this one
once you know the y never changes, and they give you a point with coordinates, you can tell what ? should be
you need to have the intuition that a vertical line is x = ? and a horizontal line is y = ?
x doesn’t change
it does
yeah idk why I’m making this super complex
let me see smth
this is the functio
this is the function y = 5
you can see two points
look at the coordinates
what is changing and what is constant?
yes
what would I write though since it can change
well u dont touch x
u put y =
and then since you know y won't change
you take the coordinate of y they gave you
7
so that would be all for that
yeah
mind helping with something similar
not rn i gotta sleep
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,rotate
Just calculate the limit as n goes to infinity.
(-1)^(n + 1) goes between -1 and 1 infinitely but the other part of the product clearly goes to zero.
@dawn ridge Has your question been resolved?
Your work is very messy.
I think you've followed the idea I was suggesting though. :)
are you familar with the alternating series test?
yea.. it goes changing sign
oh wait I just realized your question is about a sequence
regardless, for these types of sequences/series, as long as the limit as n goes to infinity is 0, then it converges
so I think yours is a correct solution
The paper like this. No way. Look at the mess.
I'm pretty sure you made a mistake in your calculations
I can't quite tell
but you got the correct answer
I think that would work.
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Prove that: (Trigonometric identities)
Is what I did correct? Thanks
The third last step has an error, though you corrected it shortly afterwards.
What you did is correct.
What's the error there?
Ohh okay I just imagined what would happen if I separated it
Would be 1 + sin x if I multiplied the negative sign to it
Rly how?
Wdym how, that's how it is. Distribute the multiplication.
$-(1-\sin(x)) = -1(1 + (-\sin(x)))$\
Distribute the multiplication,\
$-(1) \cdot 1 + (-1)\cdot(-\sin(x))$
What the hell am I doing here?
That surely gives you sin(x) - 1
@lament basalt Has your question been resolved?
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i need help
ive spent a long time trying but idk how to do it
Do you know what an inverse equation is?
yes
i just dont know how to turn it into an inverse
i tried a couple things
but it hasnt worked
apart from swapping x and y
what steps do i do?
Well once you swap x and y, you solve for y
um i have
x = (y^2 -9y +15)/3
then i solved for y in that quadratic equation
i got
(9+-√21)/2
thats the roots
but im not sure what to do know
You should have x somewhere
wdym
i equated (y^2 -9y +15)/3 to x
then i solved for y
thats what i do right
AlgebraManiacABC
Well, you keep going until y is alone on the left
And there are no "y's" on the right
so then i minus 15
divide by 9
then i have y^2 -y
y^2 - y = (3x-15)/9
well yea that
(add the $ to both ends of the eq)
lozzby
$y^2 - 9y = 3x-15$
lozzby
this?
lozzby
is that what i do?
You were closer in your first one
You just keep forgetting to divide y^2
how do i do that?
Well it would be $(y^2)/9$
AlgebraManiacABC
But now I'm afraid about having the y^2 with the y. You may have to shove everything on the left and use quadratic formula
But you somehow lost x
$(y^2 -9y +15)/3 = x$
lozzby
You can't use quadratic formula like that
oh
the right side has to equal 0
lozzby
so i find from that?
- Where did x go? 2. Right hand side must equal 0
lozzby
i meant this
Okay, now move the x to the left
lozzby
this?
Looks better!
Now you can use quad. formula
Before you do, what will be your "c?"
-x + 5?
Yeah, or, easier, (5-x)
lozzby
I would use $\sqrt{num}$
oh okay
AlgebraManiacABC
$y = (3+-/sqrt{(9 - (4/3)x - (20/3)}$
lozzby
backslash
$y = (3+-\sqrt{(9 - (4/3)x - (20/3)}$
lozzby
Give me the quadratic formula real quick
$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$
AlgebraManiacABC
Therrrrre we are xD
lol
Okay lemme plug in stuff
lozzby
this is what i have to far
AlgebraManiacABC
wouldnt it be x-5
But you had -x+5 right?
AlgebraManiacABC
wait wouldnt the -3 be 3
$x = \frac{3 \pm \sqrt{9 - (\frac{20}{3}) + \frac{4}{3}x}}{\frac{2}{3}}$
cuz in the formula its -b
Dang
so -(-3) = 3
Yeah
AlgebraManiacABC
oh right
You could also continue with:
$y = \frac{3}{\frac{2}{3}} \pm \frac{\sqrt{\frac{7}{3} + \frac{4}{3}x}}{\frac{2}{3}}$
AlgebraManiacABC
AlgebraManiacABC
Either way that isolates y and gets rid of most of the ugliness
It's still ugly though
Just a bit xD
I think so, unless we've made a mistake
thanks for the turtorial
Np xD
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Would someone please explain me this problem?
@alpine sable Has your question been resolved?
<@&286206848099549185>
It's just polar coordinates using u and v instead of the regular r and theta.
@alpine sable Has your question been resolved?
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this is a really simple
question, just some basic probability / economics math
let us say, i have a game of chance, on winning, i gain my bet back, + the value of the bet, on losing, i lose my bet, and on tying, i keep my original sum
if i double my bet, what now happens to this EV calculation?
@agile wedge Has your question been resolved?
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The first photo is the question and second is the answer. How can there be a value such as (5,-2) when x must be less than 3?
@glacial dagger Has your question been resolved?
The point (5, -2) is not a solution of the inequality (so it's not in the blue part of the graph)
The part colored in blue here is the solution
Ok but when you do something like y=<x+1, you count the line and the shaded area. Why do you not count the line in this case?
The problem is that the point (5, -2) is well outside the blue area
It's not on one of the lines that limits that plane
If the point was on the purple line then it would have been a solution
But it's not
Reply to this pls
It's not on the plane or on the purple line
Which are all your solutions
(5, -2) is here
It's on the red line, but it's neither a solution to the inequality y>3x/2-3 nor to the inequality x≤3
The red lines do not indicate solutions, they're there as a limit between the solutions and non-solutions of each inequality
If you don't understand what I explained just tell me, I can try to explain that in another way
I understand. But why did the answer not just delete the other parts?
Wdym?
Which other parts?
You have these three inequalities
The solution is the intersection of all of them
Which is that part in purple
The parts of the line that are incorrect
So why did the not delete everything except the purple?
Or are you just supposed to know that the parts that are not surrounding the shaded area are wrong?
@lilac nest
The purple part is the intersection of the 3 pictures I sent you before
Which are the graphs of each inequality you have
@glacial dagger
Depends what the problem asks. What is the whole question?
Do you have a graph?
This is another problem though
I CAN JSUT SOLVE ALGEBRAICLY RIGHT?
JUST PLUG IN 2 REAL POINTS
And solve for b?
Yes, but that graph you sent here is not going to be the graph of y=2x+b for any b
Is that the correct graph
Oh ok
In general b would be the y value when x is equal to 0 (they intersection of the graph with the y axis)
@glacial dagger Has your question been resolved?
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Prove that the following are irrational.
(i) √5
(ii) 3+2√5
do you know the proof that sqrt(2) is irrational?
I know the proof but I think the process I learnt is a bit wrong so I would like to learn it again.
proof by contradiction:
assume √2=p/q, where p and q are natural numbers and minimal (!), now it follows:
2=p²/q²
2q²=p²
therefore, p is a multiple of two and even, so p=2r for a natural r:
2q²=(2r)²
q²=2r²
can you finish the proof from here? and why is p even?
@alpine sable Has your question been resolved?
This is easy using the Rational Root Theorem, but I suppose you haven't learned that yet?
I assume I found an elementary proof but I'm rusty on these things, I'll leave it up to @alpine sable to judge me:
||Assume, by way of contradiction, that $\sqrt{5} \in \mbb Q$, hence write $\sqrt{5} = \frac{a}{b}$ with $a, b \in \mbb N \setminus { 0 }$ and $\gcd(a,b) = 1$. Rewrite this as $5b^2 = a^2$, which means that $5 \vert a^2$, but because $5$ is prime this means that $5 \vert a$. Hence write $a = 5c$, then we obtain $5b^2 = 25c^2$, or otherwise, $5c^2 = b^2$ and using the same argument we obtain that $5 \vert b$, which would imply that $\gcd(a, b) \geq 5$, yielding a contradiction.||
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Yuese
What?
this is a definate integration problem do uk that topic?
Integration?
yea
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how does this turn into squrt 49^x
can it?
isnt it supposed to be sqrt 49^x / 49^-x ?
7^((x+2)-(2-x)) = ?
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How do I solve n
(without bruteforcing)
I mean how do I find out the largest n for which n satisfies this equation
the largest?
the LHS grows quicker than RHS so eventually this will always be true
much more interesting would be the smallest
You can solve by log
Pass the two as a base of the log and solve it,
Then after you finish apply the inequation property to determine the solution set
would the smallest work? cause n=any -ve integer satisfies the inequality
Let me solve
done
Ill just give a real check and send a pic
wait, the problem is that you sill remain with a n
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doesnt it also neccessarily diverge whenever |z-z0|=|z1-z0| ?
no the boundary is always a special case
@ornate condor Has your question been resolved?
x+x²/2+x³/3+... diverges for x=1 but converges for any other x with |x|=1
..i just realised idk how to show or tell if something is convergent in complex, how do i do that?
well here the proof for x= -1 is easy and that's enough to give you a counter example
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Prove that:
(trigonometric identities)
Try rewriting cos^2x
In terms of Sinx
And factorise the sinx s on the numerator and denominator
When you cancel the cos2x over cos2x remember it becomes 1
This is the answer, we want to deal with sinx since that is what the answer wants
Also 1 over cos^2x is sec^2x not cot
@lament basalt Has your question been resolved?
Sry for late reply but may I ask what to do next?
I absolutely don't know how to answer this other than the factoring method used in trinomials
So rewrite the denominator in terms of sinx
Using the cos squared x + sin squared x = 1 rule
Since the answer we want to prove has only sinx terms, we want to get rid of all the cosx
Then you factorise the fraction and cancel
Sry wdym on this?
Also
This, right
Ok so only change the denominator at first, leave the numerate alone
*numerator
You should not have a secx at the top
Oh only changing the denominator to 1- sin^2 x?
Yes
Then you can factorise the top and bottom, and cancel. you no longer need to use any trig identities
Sec^2 x = 1 + tan^2 x
Yea, but you don’t need to use that for this question
I got this instead
I just simply made a 1+ sin x, separating it from the rest
Treat the top and bottom part of the fraction as quadratics
Then factorise as if it was x^2 +4x + 3
No I mean there's still some additional sin's, coefficients, and sec^2 x
Even if I factored out 1 + sin x/ 1 + sin x
Check this, you see how I factorised it like a quadratic
I did different in which there's a sec^2 x
Is that the only way?
Possibly, but I haven’t seen any other way. You don’t really want to make a secx when it asks for the answer to be in sinx only
Oh okay thanks
.close
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Hi in class we didn't study linear graphs and what's a linear equation but we did by accident get a question with a linear equation so I wanted to check if I solved it right and if my graph is right too
The equation is (x-2) (x+3)=0 btw
i dont see what is the question...
Your calculations look good. You calculated the roots of (x-2)(x+3). But thats actually not a linear equation.
Then what type is it ?
If you multiply that out, you see that it's a quadratic.
oh is the question points of intersection of (x-2) (x+3) = 2x + 1 = y
So I should use the roots formula ?
And this also means my graph is completely wrong ?
<@&286206848099549185>
Like because x×x and 2×(-3)
so now you just solve with quadratic formula
yeah
what exactly does the question want you to do tho ?
Solve the equation and draw a graph
he wrote (x-2)(x+3)=0
so i think that's a quadratic
a graph of what ?
so your graph is wrong
Its just an equation though with no context
its not a function
x^2+x-6 aka (x-2)(x+3)
i mean it looks ike a quadratic
can you show the question ?
OK thanks
the question was solve for x and draw a graph
the equation you solved can be used to pinpoint the roots of the quadratic (x-2)(x+3) but it all depends on the question
i think
.
The question is on top (x-2)(x+3)=0
do you have the picture of the segment itself maybe ?
And I should solve the equation and draw graph
he literally typed the question
I might as well solve for x=2 and x=-3 and draw 2 vertical lines instead as well
It's not in English
post it either way
????????
bro
it's obvious what he is asked to do
draw a graph of x^2+x-6
and solve the quadratic
I'm sorry but it's not that obvious to me
it is when he typed out "I need to draw a graph and solve for the roots" 100 times
and besides, how can he be asked to graph a quadratic when he hasn't even studied linear functions ?
i have no idea
@inner kayak if you have the question itself from the book or source post it here even if its not in english, that way we can get a better understanding of what you need to do
You can't graph an equation that you're given
you can graph a function, but I don't see a function in your solution
so its a bit weird to me
It's supposed to be for 8th grade our teacher accidentally let this question slip into our homework
When I googled the equation a bit I falsely understood that it's a linear equation and tried to draw a graph for it
8TH GRADE
I now understand that I was wrong
holy shit in what education system do you not learn linear equations until grade 8
stop right there doc u might get banned for underage
?
grade 8 isn't underage
disord tos is like depending on region
it's like 14
I'm over 13
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Bit confused on how I would solve this by hand?
I have to calculate the integral
Substitution
Hmm, okay!
Its very handy to identify functions and their derivatives, this allows you to see immediate subs and even solve the integral immediatley
I'll watch a video rq on substition a bit tim since I did it last time
The video shows this formula?
Is that correct?
thats the general theorem of substitution yea
but try reviewing notes and example of substitution
this should be pretty easy if you understand how to do subs and how they work
yep but i have held sabbatical year
So haven't touched math for a whole year
hence why im a bit rusty
but actually watching this video 1 minute already made me remember more
yea ofc
which is why im recommending to review the method
If you after reviewing you still struggle you can come back or even ping me
Is it okay i ping you and tell you what I'm going to try and do?
And then you can just say no or yes
sure
Okay thanks! then in 5 minutes I'll write something haha!
Also consider integration by parts!
It's simpler for this problem imo.
hmm .. ?
is it ?
Altough I'm bad at integration by substitution😅
if it had been xlnx i would agree with you
Well I'm not sure actually. 😅
well you can try it
. have this in mind
lnx=t, dx/x=dt, becomes integral 0 to 1 {2t}=1^2 - 0^2=1
@surreal meteor Has your question been resolved?
Something like this?
Do i then put -2/x*dt at the end?
with your sub you can replace 2dx/x - > dt
and then you're left with lnx when according to your sub you can replace with 1/2*t
after that you need you have to replace the integrals limits according to your sub
you mean like because its a constant i can just take it out the integral
something like this
I mean you're right, but I wasn't talking about that
I just said how to rewrite your integral according to your sub
but that changes my sub now
it's just 1/x
no9w
t=1/x
Now right?
t=g(x)=ln(x)
It doesn't chage your sub
you can maintain your current sub you just need to rewirte the integral accordingly
This sub will also work (and its actually a better one)
Yes so now
you can always do whatever sub you want
you just need to make sure you rewrite your integral accordingly, and the integral limits
dt=1/x*dx
the new limits as written here
correct
But don't I need to get it on the other side
But notice that the expression 1/x*dx already exists so you can replace it with dt
Yes that's the outer function?
Right
Or is that a big

Thought it was like since this is the same as the red
Then I'm a bit confused on what you mean 1/x*dx already exists so i can replace it with dt?
Don't I have to isolate dx
So I can replace dx with dt
and substitute t
after you did your sub you've correctly expressed the differential dt=1/x *dx
hey im kinda confused and not really sure about my solution for:
So essentially you can write your integrand as 2lnx/x dx -> 2*lnx * (1/x *dx) => 2lnx * dt
try asking your qeustion in an available channel @alpine sable
Ohh!
which?>
read #❓how-to-get-help
yeah im reading
we essentially want to scale our dx differential to match our sub's differential with in this case is t (the differential would be dt)
hmm.. why did you write t/x ?
I substituted ln(x) with t
but dx≠dt
since we said t=g(x)=ln(x)
correct
You can't replace dx with dt
Oh so I can't do it unless dt=dx
even though you expressed that 1/x *dx = dt
dt != dx in this case but rather 1/x* dx= dt
I think this is first time you do integration right
No no, but like a year and 3-4 months ago since
Can't even open my notes since my computer is broken
Hm
The problem you send, only need 2 lines if you have been doing enough integrals
Well, that is good to know haha, don't see how that helps though 😛
Also you are wrong at this for not just t/x but
Also the bound
you set t=ln(x) right
Yes
Then the new bound for t
Not x anymore
When x=1, t=ln(1)=0
When x=e, t=ln(e)=1
$\int_0^1 f(t)dt$
Darkness
Its how the sub is defined
its written here
the new bounds are g(a) and g(b), where g(x) is the subbed function
Yes and t=g(x)
So just insert the bounds into them!
That actually makes sense!
yea essentially
That's waht the theorem states
After replacing the bounds you need to rewrite your integrand using your new sub
Yes, to recap
so if t=lnx
dt=1/x *dx
you've received the expression of the differential in relation to t
,tex
$I=\int_1^e \frac{2\ln(x)}{x}dx\\
t=\ln(x)\Rightarrow dt=\frac{1}{x}dx\Rightarrow dx=xdt\\
x=1\to t=\ln(1)=0\\
x=e\to t=\ln(e)=1$\\
so you can directly repalce the epression 1/x * dx with dt directly
Darkness
I think we should go another line where dx=xdt so he can substitute correctly
It's just multiply both side for x
multiplying both sides by x
So now instead of writing dx, you can write xdt to the original integral
and where there is ln(x) you write t
It's how substitution works
I'll definitely read up upon this lmao once im done with the assignments, just wanna get done with the assignments before uni start, but then once im done, i'll read up on the weakness and this is definitely one without a doubt
Can you do next step
Next step of this
Because the question is designed so
so is that right?
Yes
Yes
Yes
Nice
Okay so thanks man!
I'll definitely read up on it
Luckily they added a bunch of pdfs
Do you have any videos you could recommend to watch?
Well integration is just practice
No doubt
You need practice first
Watching videos now ain't help and may confuse you more
Watching videos is when you have enough training
khan academy is not shabby
Oooor it might actually make me remember what I was taught lmao
Yes, that is true though
But like if you are new at ordinary technique's
But perhaps once my pc is working I can go check my old notes on it
Getting exposed to new techniques just confuse you mkre
Darkness
Actually you are wrong at this step
Integrate of t is not t
looks right
For the recrod btw
notice that the integrand was in the form of g'(x)f'(g(x))
which is the direct derivative of the function f(g(x))^2
ye chain rule