#help-0
1 messages · Page 226 of 1
im so done with it
like
for a i got 2 3 0
but idk how im suposd to get the second part
deadline?
show your work?
this isnt an assignment
its hw
for my test tmrw at 4pm
i cant take a pic im in the dark my mom will scream at me if i turn it on
no wym
i got]
1 0 0 | 2
0 1 0 | 3
0 0 1 | 0
by doing rref
which is so anoying
and takes me slong
is there any tips for that
we can’t help if we don’t know what you did wrong. send your work if you have some
they already said they are unable to
oh
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I am a bit confused with the second part of the working out
From "For 2 distinct roots" onwards
I believe there is an error in factorising in the 2nd line
However the last line corrected it.
My main concern is how to determine that the arrows point out
hello again
In my original answer, I got m > -2, 6
discriminant must be greater than 0
I understand that.
^
Do I need to recognise that it is a graph of a parabola
because by just solving the inequality, I get m > -2,6
I am familiar with the solutions and recognised that there are roots at -2 and 6
However getting from here to here
they made a mistake
i believ it should have been (m+2)
(m-6)(m+2)
but even at that, I don't understand how the m+2>0 becomes m < -2
The answer is correct but steps are wrong
do you know how to use wavy curve method?
As stated in the original message, I have determined this.
No
I may know the method, just not the name of it
never heard of that
i’m not too sure myself but the way i do it is just the smaller number is m < number and the bigger number is m > number
I see, but thats with the assumption that you have a parabola
I was just wondering if that was absolutely necessary to recognise before stating the domain
Since originally, I waved over the fact that it was a parabola and just did m>6 since that outrules m>-2
I was merely looking a the inequality that I made
im not sure myself in this too much as i have never bothered to venture deep into solving problems like this
i usually find roots and apply what i need to do to achieve x sols
Gotcha, I suppose next time i just have to recognise early that I am solving for a parabola
Anyway, thanks for clearing it up
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I'm so confused why my teacher divided the leading coefficients
Ok so I graphed the first equation as seen in red. The limit is clearly -infinify
Then I changed the power to 6
When I cancel them out, it becomes -x^3
If I were to plug infinity into this, it would just become -infinity again
Wait Holy shit I'm stupid
Nvm
As x approaches infinity
It goes to negative infinity
But not as x approaches -infinity for the power of 6
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✅
Wait but hold on
If I cancel the leading coefficients out, I get x^3
When I plug infinity into that, I should get infinity, no?
So why do I get -infinity on both sides
Is it because when I factor it I get $\frac{x^2(4x^2 + 5)}{x - 4}$
And then the 4x^2/x = 4x
But even then
Both are positive
I'm so confused
TreetopperJoey
Why is the limit as x approaches infinity in $\frac{4x^4 + 5x^2}{x - 4} -\infty$ ?
TreetopperJoey
Nvm it isn't 💀💀
try using l'hopital's rule
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Oh I'm not in calculus yet
Sorry
Precalc
My friend told me about that
He said it's super easy
But seeing as my test is in 2 hours probably not worth learning
yeah it just looks like that up close
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they're stdevs of different things
trying to think of a way to put the latter into words but i cannot find the right words
@limpid stone Has your question been resolved?
how would i tell which to use in waht situation

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Any idea on part(b)?
the way the circle is written is pretty unusual
see if you can write in the form
(x-a)^2+(y-b)^2=c
Don't get what it means to be OQ:QR = 1:4
The circle can be written as (x-3)²+(y-6)²=25
quick one
yes
Ration of there length
I know but how can i calculate the m
m = 1/2 or -3/2, when i put y=mx into C and calulate using 5a^2 = 36b
ye
oh btw use of graphing calculator in Hong kong exam is prohibited so actually i draw by hand when i'm doing this question in my university entrance ex am
im not using a graph dw i just wanted to show ykwim
ok
Only if we could get the coordinate of Q
if the line y = mx intersects the circle at a point p, that would mean that
(x-3)^2+(mx-6)^2=25
also
if you are familiar with the section formula (i think it can be used here)
Yep
So we got one coordinate of Q
(0, something)
Now I think that
We can use distance formula for the radius
Like
$\sqrt{(3-0)^2 + (6 - a)^2}=5$
Random Guy
Yep
Solve for a and we get the coordinate of Q
Now use slope formula to calculate the m
why is Q on the y-axis
✔️
you have not explained why
how is that x1 and x2
i think you are applying the formula incorrectly
this is why india's workforce is mainly in tertiary sector
Bruh
Irrelavant to section formula, seems i've found the answer
$x^2 + x\frac{-12m-6}{m^2+1} + \frac{20}{m^2+1} = 0$
小馬
damn still need to use section formula cuz O,Q,R are collinear
So basically The coordinate of Q is (x2/5,y2/5) now if we apply distance formula between Q and center we should be able to get the answer
By Section Formula :
$$\frac{4(0)+1(x_2)}{4+1} = x_1}$$
Hence,$ x_2 = 5x_1$
小馬
Compile Error! Click the
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Then use 5a^2=36b, solved
What is the value of M then
slope
Let me solve it using my method
Wait a min
,w (3-x/5)^2+(6-y/5)^2=25, (3-x)^2+(6-y)^2=25
nice
This is disaster 💀
not really, i used the results from (a)
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What is the differential equations that matches the given vector field. Choose the correct answer:
How would I start solving this?
Look for gradients of 0 on the vectors
Integrated each answer?
well the vector field is circle shaped
so I integrated the first one and got a circle as an answer
I mean if it works
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Trigonometry (ASTC)
i really dont understand pls help 😭
sin-1
yes
then create 2 equations
sin-1 (3/4)?
howw
because -3/4 cuts the sin curve in 2 different positions
when u plug in calc u get -48. smthn
then
between 0-360 you can see we have to
add 180 + 48.smthn
but they want me to use the ASTC thingy
i use the calcultor to convert it to that
can somebody try solving and sending their ans
no im not tryna get you to do my homework ive got like 30 questions i just need 1 example to work backwards and ill figure out myself
(i always work backwards and figure out myself)
plss 🥺
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Given two positive different rationals $x, y$ such that $$w=\frac{x+\sqrt{y}}{y+\sqrt{x}}$$ is rational. Prove that $x$ and $y$ are the square of rationals.
$nichoals$
How do I solve this?
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I am just confused, here am I supposed to remove the denominators of both equations to find if a1 and a2 equals b1 and b2 but not c1 and c2?
You can make b so firs equation LHS is equal to second equation LHS, so that would make impossible to solve cause they have both different RHS
to do that, you simply divide second equation coefficient with the first one, and the result multiply by the first coefficient of the first equation that multiplies x and with the second one.
@finite coyote Has your question been resolved?
a/a1=b/b1≠c/c1
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are those all the trigonometric and hyperbolic variations of tan ?
depends what you mean by "variation"
all the other functions that involve tan or tanh
More complex functions that are just formed from the basic trigonometric or hyperbolic functions
"more complex"? is (tan(x))^2 not more complex?
sqrt(tan(x))?
e^(tan(x))?
like i dont think you're accurately saying what you want
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Wait how do I find a a gcd with just 1 negative value
Uhhh could you elaborate please I don’t understand
Negative integers are divisible by positive integers
And the GCD, LCM are defined to be positive
gcd for negative numbers is defined as if you just ignore the negative sign
same for lcm
Wait for example like gcd(-2,4) would be 2 right but what about lcm(-2,4) wouldn’t that be -2
Is that right?
Ohhh right but like -2 is a multiple of 4 isn’t it??
Oh wait nvm
If it’s negative it could be like negative infinity
I see now so is the lcm 4???
Yes
And gcd(-2,4) is 2 right
Yes
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I'm going to write my math exam in about 4 days and I'm struggling to understand "Cubic Sequences" would anyone be kind enough to explain it thoroughly? Thanks,
Have you looked back at notes or looked up resources on that?
Both and unable to under stand it
Cubic Sequences, how to find the formula for the n-th term, using the difference method.
Cubic sequences of numbers are characterized by the fact that the third difference between its terms is constant.
We learn the formula as well as how to use it using 2 examples.
Visit the Cubic Sequences Page on my Website Here:
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hi i’ve been trying combinations but cannot seem to get a rule that works :/
only clue i’m onto atm is that they’re not all multiplied but the first digit is added/subtracted due to the 0
I figured it out
Yes, there isnt any multiplication, thanks to the Safe Harabour Vs Dangerous Devils match you can know
They would have scored 0 points then
Wait no 😭😭I was wrong
It doesnt apply for each one
i feel like i find a rule
Im a fraud sorry👍
and then it doesn’t work for another 😭
Right
all good ❤️❤️
<@&286206848099549185>
there doesn’t seem to be a consistent combination…
the way i do it is actually getting the equations from 7.9.11 = 92 ; 2.12.5 = 95 ; 1.2.9 = 30 and then set x y z in them and somehow it worked
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Does this have a constant rate of change? I'm trying to figure out if it's linear or not
Have you done anything?
Not yet, it says to find out if the table is linear or not
Do you have any idea how you'd proceed?
Not really, no
Well, can you find the rate of change in y with x, for any two given points?
I have difficulty with it
Do you atleast know the formula?
Isn't it two coordinates with a line separating them, or am I confused?
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How do i divide indices with different bases, same exponents
$\frac{x^a}{y^a} = \left(\frac{x}{y}\right)^a$
ΣAC
yeah
thanks
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from a deck of 52 cards what is the probablity that 2 kings are draw when randomly selecting 4 cards?
isn't this just $\frac{4C2}{52C4}$
Text out of $$
Bedsheat
ohhh i see
Yeah I think that's the answer
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quick question
p^2 and higher powers can be thrown out
wdym by thrown out
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find when the product (r-1)(r+2)^2 is equal to zero and let those numbers be equal to h-5 and solve for h
(a product is zero when one of its terms are equal to zero)
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I am bad at math and need help with this
backround info
This is a minecraft minigame where you play hide and seek and you can use taunts. Taunts give xp which increase your level. I want to know the best taunts to use to get max level the quickest. The game lasts 5 minutes and the seeker starts seeking 20 seconds in and you can start using taunts 20 seconds in, so in total I have 280 seconds to use taunts and gain xp while hiding.
Taunt 1 gives 3 xp with a 8 second cooldown
Taunt 2 gives 5 xp with a 15 second cooldown
Taunt 3 gives 6 xp with a 18 second cooldown
Taunt 4 gives 8 xp with a 23 second cooldown
Taunt 5 gives 10 xp with a 30 second cooldown
Taunt 6 gives 12 xp with a 35 second cooldown
Taunt 7 gives 15 xp with a 45 second cooldown
Taunt 8 gives 18 xp with a 54 second cooldown
What is the best taunt to use for the most xp in total during the 280 seconds that i have?
k thanks
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how did they get the coordinates?
Do you mean the values x = -1.732 and x = 1.732?
They're finding the intersection between the initial equation y = x^2+4 and the line y = 7
So, set them equal to one another, solve for x
The decimals are just +/- sqrt(3)
wait wait set y = x^2+4 equal to 7?
correct
back in algebra, that's how we learned to find where two functions intersect
take the two "y" expressions and set them equal
y1 = x^2+4
y2 = 7
So,
x^2 + 4 = 7
ah but what about y=1?
We attempt the same thing, but no solution emerges
So, the line y = 1 does not intersect the equation y = x^2 + 4
y1 = x^2 + 4
y2 = 1
x^2 + 4 = 1
x^2 = -3
No Solution
oooh right, can i try a different example and come back if im lost? or do i have to close immediantly?
if it's a different example, probably close this thread and reopen a new help
gotcha, lemme try this example myself
ah ok i got it, its also pos and neg because your taking the sq root
gotcha thx man
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doing this question again and cant help but think its true?
didnt you come up with a counterexample earlier
Show your work, and if possible, explain where you are stuck.
proved what?
the statement?
it is not true by your own counter example so you messed up somewhere
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I love it when my deniminator suddenly goes from being -(x+1) to -1(x-3)
it goes from 4-(x+1) to -(x-3)
but how
evaluate the denominator
4-(x+1)=4-x-1 = 3-x = -(x+3)
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How to find the surface area
Yeah
using Pythagoras, you can first find the length of the diagonal of the base square with side-length 12cm, then Pythagoras again for the diagonal of the triangle, now you have all 3 lengths of the triangle, and you should be able to work out the area of the triangle
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looks right
Righto, answer sheet stated something else
just wanted to check I was interpreting the values correctly
thanks
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hi
id like some help with part b
so far ive been able to substitute cosxcotx into the lhs of the equation
said that x = 3x - 50
thus x = 25
but i dont know what else im meant to do now
I believe that's it
idk apparently theres 2 other answers
Oh I see I guess you could have where cos(x)=0 be a solution
Certainly 0=0 is true
Blue Guilmon
Oh they aren't functions in this tex
$\cos(x)$
But you get what I mean just disregard the /'s
@pseudo ice
Oh soz on my phone xD
ok so
Try solving for the zeros of this instead
$\cos(x) \cot(x) - \cos(x) \cot(3x-50)=0$
Blue Guilmon
o
Then it becomes more obvious why cos(x)=0 is a solution
Factored you get $\cos(x)[\cot(x)-\cot(3x-50)]=0$
Blue Guilmon
Yup
cos x = 0
Because if $a \cdot b =0$ then either $a=0$ or $b=0$ in algebra
Blue Guilmon
so then x = 90
Yup
Hmm
the cot(x) = cot(3x - 50)
Try multiplying everything through by $\sin(x)$
Blue Guilmon
Because $\csc(x)=\frac{1}{\sin(x)}$ on the left and so you get $1-\sin^2(x)$ on the left which using pythagorean's is $\cos^2(x)$
Blue Guilmon
Then solve the zeros of $\cos^2(x)-\cos(x)\sin(x)\cot(3x-50)=0$ yields an equation $1-\sin(x)\cot(3x-50)=0$
Blue Guilmon
I may be overcomplicating it tho
it could work but this question is technically meant to take 5 minutes lol
Yeah it's a bit tricky but not hard
Yes it does
I see
Yeah cotangent had a period of pi or just 180
Has*
So $\cot(x)=\cot(x+ \pi)$
Blue Guilmon
Substitute that into your original cotangent equation on the left
Except maybe 180 instead of pi if they're using degrees
mhm
You probably wanna write a general solution to these
general solution?
That would've saved us a lot of trouble haha
Yeah trigonometric equations usually have a solution that is periodic
Meaning they happen on regular intervals because the functions themselves are periodic
oh true
So if you are working with specific bounds
Write up a general unrestricted solution first
Then just plug in numbers until you get everything in your bounds
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$$
\int \frac{dx}{a^2\sin^2x+b^2\cos^2x}
Given ab not equal to zero.
This can be solved by dividing by \cos^2x quite easily. This is also the solution in the solution manual is to divide by \cos^2x then use u-sub. for tanx. One question though. How come it is valid to divide by cos^2x? Wouldn't it sometimes be zero for the interval over which the integral is being calculated?
$$
Lily.
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$$
\int \frac{dx}{a^2\sin^2x+b^2\cos^2x}
$$
Given $ab$ not equal to zero.
This can be solved by dividing by $\cos^2x$ quite easily. This is also the solution in the solution manual is to divide by $\cos^2x$ then use u-sub. for $\tan x$. One question though. How come it is valid to divide by $\cos^2 x$? Wouldn't it sometimes be zero for the interval over which the integral is being calculated?
maximo
what do you mean by "divide by cos^2 x", can you show what they did? @merry plinth
where it is 0 has measure 0 or sth
that's not enough jester
you can't integrate 1/(x^2) from -1 to 1, even though 1/(x^2) is only udnefined for a singleton
Sure!
$$
\int \frac{dx}{a^2\sin^2x+b^2\cos^2x} =
\int \frac{sec^2x dx}{a^2\tan^2x+b^2}
Let u = tanx
du=sec^2x
\int \frac{du}{a^2u^2+b^2}
$$
Lily.
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reaction for more information.
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Sorry, Idk how to properly format for the bot
,tex
\begin{align}
\int \frac{dx}{a^2\sin^2x+b^2\cos^2x} = \
\int \frac{\sec^2x dx}{a^2\tan^2x+b^2}\
\text{Let }u = \tan x\
du=\sec^2x\
\int \frac{du}{a^2u^2+b^2}\
\end{align}
Feels like that was the culmination of almost all of real analysis until it wasn't
maximo
they didn't divide by cos^2(x)
There we go. Except im missing a dx lol
It is an indefinite integral
then you would just say this works only when cos^2(x) =/= 0
same way it only works when a^2sin^2(x) + b^2cos^2(x) =/= 0
i mean but the author doesnt state anything about cos^2x not being zero
so would solving it that way not be a full solution?
do they state anything about a^2sin^2(x) + b^2cos^2(x) not being 0?
it would still be a full solution, as far as your class is concerned
uhh, i dont think its possible for it to be zero given ab not being zero
tho maybe it can be for negative values of a and b
it's implicit that the denominator is nonzero
yes
via the same handwaving we just take cos(x) =/= 0
and it may even converge in that case still
but that's not what this problem is about
also it looks like a=-1 and b=0 results in a function that is sometimes zero so yes sometimes the denominator is zero for certain choices of a and b
ab is nonzero
yes
so those choices aren't allowed
the denominator is never zero
the solution given is complete as far as your class should be concerned. is this for a calc 2 or similar class?
a=-1 and b=1 means ab=-1 tho
a and b are squared in the denominator
they will both be positive
as will sin^2 and cos^2
its not a class im just doing problems provided in a calculus book that ive been slowing working through
then chances are the calculus book isn't concerned with the case for cos^2(x) = 0
oh wait yeh ur right so the denominator is never zero for any choices of a and b
whatever you get for the answer, plug in a value that would make cos(x) = 0
im confused why it would not be concerned for choices of cos^2x = 0 though?
because calculus books at these levels are more about integration techniques rather than being rigorous
have you seen a rigorous proof for u-subtitution working?
if you want to justify what happened for values of x making cos^2(x) = 0
note that sin^2(x) = sin^2(x) * cos^2(x) / cos^2(x), for values of x such that cos^2(x) is nonzero
for those values of x, though, we can still extend the function sin^2(x) * cos^2(x) / cos^2(x) naturally to the value of sin^2(x)
the book did in fact cover a moderately rigorous proof of u-sub
moderately rigorous should be the key term for you
okay so taking a definite integral from pi/2 to pi for example you would end up with zero in the denominator of the tan function tho?
you would just not consider that point
yes that's still well defined
its just the graph of the function with some choices of a and b
i don't see why that point wouldn't be considered there
graph sec^2(x) / (tan^2(x) + 1)
yes, they are equivalent, but as you said one is not defined for specific values of x
but they have a natural extension to the graph where it's well defined
that's what i would have thought
in particular, the evaluation at those points given by the former function makes our latter function continuous
im confused how that is possible
how what is possible
consider the graph of 1 v.s. the graph of x/x
one is defined at x = 0, the other is not
but it makes sense to extend the graph of x/x to be 1 at x=0
how the sec^2x/(4tan^2x+16) is continuous
oh okay
because it's the most natural extension for it
i guess there is still a hole then at pi/2?
yes
but
what is the integral at a single point?
think of a riemann sum
and think of what the with of the rectangle would be
its zero. or rather can be ignored since it does not contribute
yes, and the reason why it can be ignored is because it is a hole
i guess the point is since the area being excluded by cos^2x = 0 is only at single points that it doesnt impact the sum at all?
it's more that
we can include those points with a natural extension of the function
hence why they are holes rather than jumps or asymptotes
when you say you can include those points with a natural extension do you just mean redefining the function to include the points where there are holes at those points?
yes, kind of like $f:\mathbb{R} - {0} \to \mathbb{R}, f(x) =\frac{x}{x}$ and the extension $g:\mathbb{R}\to\mathbb{R}$ given by $$g(x)= \begin{cases} f(x) & x \ne 0 \ 1 & x = 0\end{cases}$$
maximo
note that g(x) is just the function g(x) = 1
this is a very simple case of such an extension, and not all functions have extensions like this
but in your case, we do, so we can just ignore the missing points knowing there's a nice inclusion
well its also possible since the right and left limit approach the same point
yes
that was another way to look at it
let f be the integrand for your integral
then we just consider $$\lim_{\varepsilon\to 0} \int_0^{\frac{\pi}{2} - \varepsilon} f(x), dx + \int_{\frac{\pi}{2} + \varepsilon}^\pi f(x), dx$$
maximo
that would be the same as just taking:
$$\int_0^{\pi}f(x)dx$$
right?
Lily.
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im making my final SAT revision but some word problems are confusing me, particularly this
have you tried anything yet?
b = beef
c = chicken
@rapid scaffold
yeah
im trying to do it mentally quick according to exam setting but i can't decipher it much
i suck with word problems
when you see "equal to", what do you think you should do?
if b and c represent the prices and they are equal
make x subject
then plug into other equation
not quite
that's what I'd do in a regular situation
you have equations for b and c and you want to find when they are equal
so if you were to set b equal to c, could you find a value for x?
now that makes sense
im used to long-form questions so word problems are new to me
and remember, when you do set the equations equal to each other and solve for x, x represents the number of weeks
and you're asked to find a price
then plug x back into either equation
actually both
value should be the same then
correct
this should be 4x - 3x - 3 <= -5 correct?
but then it gives x <= - 2
right
so all solutions less than or equal to -2 would be valid solutions
and only one of those options isn't
-1 is wrong then
wrong in what sense
yes, correct
Could you please post this in an available channel in the Math Help Available section? [bear in mind that #❓how-to-get-help isn't telling you to take channel 0 specifically, just one of the ones that are unoccupied (so have no names on them)]
Ok thank you
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For this, why is it a relation
I understand why it is one to many now
I used the vertical line test
is it assumed that the middle section in that graph is exactly parallel to the y axis?
Even if it is true, there is no way for student to guess teacher’s intention just by looking at the picture. 😂
Okay, but my original question is why is it a relation?
Let me confirm, the red pen is the correct answer
looks pretty function to me
Thats what I thought too... the answer sheet says it is a relation
thus, I was asking would I have had to assume that this part in particular was parallel to the y axis
Because that would be the only way where a line of x would pass through the graph twice
The graph shows a (infinite) collections of ordered pairs (which is infinite since the graph is continuous). And such collection is a relation if not a function.
Could you elaborate on that, I don't fully get what you mean
Right now, the only method I have of determining if a graph is a function or relation is by inspection
and thats purely through a vertical line test
this is a point of inflection, more specifically a point of infinite steepness
Quick googling on the exact definition on "relation" first.
A relation between two sets is a collection of ordered pairs containing one object from each set.
The graph you are having joins a bunch of (x, y), and the graph tells whether and how points should be joined. This "rule" itself is a relation.
So are you saying for a function, it needs to be one to one?
it should be a function, flipping through my notes it seems like it’s a graph of -x^(1/3)
Some other googling.
The difference between a relation and a function is that a relationship can have many outputs for a single input, but a function has a single input for a single output.
So loosely speaking, a 1-to-1 (and also many-to-1) "rule" is a function, and all others are relations.
Right, I thought so too. In that case would the correct answer also be one to one?
Additionally, for this question. Would it be a relation and many to one?
Because for when y=0
you have 3 seperate roots of x
Yes for (g) your answer key or your teacher is definitely wrong. 😂
What is the "M-O", "O-O", and "M-M" notation begin used here? 
Me being too lazy to write many to one, one to one etc
It’s ok, in higher lv math course you won’t be needing to write these terms that often.
ah ok ty 
Anyway, I think it should be fine. A lot of the ones that I got wrong I believe it may be the answer sheet error
Thanks for the help
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I don't need help with the whole question i just have a question for a specic part of the equation. When working what the quadratic equation i noticed that depending on which value of x i used i would either get the right answer or wrong answer. And im wondering does this mean that i will only get the right answer if i use an a value of x equal to or less than 3? My question wasn't answered before it got closed so I'm asking again if thats fine
that is fine to ask again, btw next time just react to the bot's message with a ❌ when it asks if your question is resolved, and that will keep your channel from being closed
Could you be more specific what your question is?
basically I am trying to solve A. When I solve for A using the points (2,4) I get the correct answer of -1/2. But when i used the points (6,0) I get a wrong answer of 0. So i am wondering why that is the case
Could you please tell me what "A" is?
What is the original question that you are looking at
Ok so i am trying to find the equation y=ax^2 + bx which is a quadratic. (C=O) And I am trying to solve it by using the turning point and differentiating the equation into 2ax +b = 0 (since dy/dx at turning point is 0). I then make b = -6a. Then substitute in b=-6a into the original y=ax^2 + bx quadratic
this was the og question
and you are trying to find the equation of that quadratic?
yeah
Okay gotcha
I know that theres another method to do it. I'm just trying to figure out why the method im using spits out two different answers depending on whether i use points (6,0) or (2,4)
which my working in the image i sent kinda shows
<@&286206848099549185>
@wispy rampart Has your question been resolved?
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f(x) = 3 + (x-2)^(2/3) in [1,3] , is rolle's theorem applicable on this function ?
it is continous and it is diffrentiable when x is not equal to 2
so rolle's theorem should be valid right ?
Do you know the requirements of Rolle's theorem
what makes this not differentiable at x = 2
yea , it needs to be continous in [1,3] and diffrentiable in (1,3)
this is it right ?
f'(x) was coming as infinity so hence it it not diffrentiable ig
(2/3)
oh i thought the exponent was a 2
Does this answer your question
yea sorry mb , i edited it
does what ans my ques ??
but its only non diffrentiable at one point ?
for values greater than 2 it would be diffrentiable
"Differentiable on (a, b)" means differentiable at ALL points a<x<b
oh i wasn't aware of that 💀
ok so ig this clears my doubt thanks
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This is my work so far can anyone help steer me in the correct direction?
I'm not sure if im doing it right
for A
I'm trying to work out the proof for k+1 but im kind aconfused
better to put question marks above the <'s for P(k+1) and the stuff that follows
$(k+1)!^2 \neq (k+1)^2!$ btw
Ann (glomed)
so you have $(2^{k+1} (k+1)!)^2 \overset?< (2k+2)! (k+2)$
Ann (glomed)
from (2^k * k!)^2 < (2k)! (k+1) check the factor by which each side grows
on the left that will be (2(k+1))^2 and on the right it will be (2k+2)(2k+1)(k+2)/(k+1), or 2(2k+1)(k+2)
compare those
glossing over some details here jic
@livid crypt Has your question been resolved?
I worked on it and got a similar answer to yours thank you so much!!!
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@livid crypt Has your question been resolved?
``for any $y \in \mathcal{E} \times \mathcal{E}$ there exist $k \in \mathbb{N}$ such that $f(k) = y$" \ what about $(2,4)$?
bee [it/its]
@livid crypt
What do you mean what about (2,4)?
if y = (2,4) then what's the value of k such that f(k) = y?
it looks like your proof claims that it's y/2, so in this case (2,4)/2, but i don't know what that means
This is my friends work and im trying to make sense of it for my understanding
im lost which is why Im looking for clarification
but are you saying that f is not onto?
yeah the function they defined in c isn't onto
i think their answers to a and b are correct
no E x E is definitely countable
they just took an approach to proving that that doesn't work
oh okay thank you for helping anyways
I appreciate it
unless u have a proof that works I can try to find it on my own
so you can end this channel so someone else can ask a question
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help
example 21
what is that with 2! ways?
why that is written?
why is that required that in how many ways vowels can be arranged?
it's like... if you look at all the permutations of GARDEN
all 720 of them
you could make 360 pairs of them, where two are paired if they just have A and E swapped
so NARDEG and NERDAG are "paired"
for example
and only one thing in each of the pairs is valid (the one that has A before E)
so half of the total arrangements are valid
but 2! has nothing to do with it
2! = 2
yeah
it just coincidentally looks like 2! has nothing to do with it because 2! = 2
what if the word was GARDEO?
it's not irrelevant lol
if there were 3 vowels, the next line would instead say in 1/3! of the 6! arrangements blah blah blah
instead of this which is basically: in 1/2! of the 6! arrangements
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np!
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For this question, it says to prove it, but im finding that it's false, is this correct?
(Sin(x) / 1 + sin(x)) - (Sin(x) / 1 - sin(x)) = 2tan^2(x)
Btw, I got 2tan(x) = 2tan^2(x) in the end
as it stands that's not true although it does equal -2tan^2x
@deep crater Has your question been resolved?
So what would happen then?
i would ask your teacher about that since you can't really prove a false statement
try to work to prove that it equals -2tan^2x in the meantime
Hmm
Did you get 2tanx tho?
no, that's not correct
What did you get then?
as i said, i got -2tan^2(x)
Can you show how?
try multiplying each by 1 (same on top and bottom) to make a difference of squares
Yeah I'm still confused
so we can always multiply something by 1, and 1 can be any fraction as long as the numerator = denominator
the denominators on each fraction look like a difference of squares, so try converting each fraction to a common base using that
(1+sin^2(x))(1-sin^2(x))?
ok so let's start with $\frac{\sin(x)}{1+\sin(x)}$. What happens when we multiply by $\frac{1-\sin(x)}{1-\sin(x)}$?
cloud
The bottom and top get that value
what do you mean?
They get those value added once multiplied
so what does your first fraction look like now?
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Why doesnt this function have an absolute maximum? Is it due to the interval being open on one end?
yea that's the gist of it
f(x) has a least upper bound of 4 on that interval although it cannot actually attain that bound
for an absolute max it needs to be the least upper bound and attainable
you can inch up as close to x=2 as you want but can't reach it, at the same time f(x) inches towards 4
Thanks
np
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can someone explain to me how the answer is not 1/3
do you have work for how you calculated the integral?
you most likely screwed up at some point in your calculations
oh right
no ok i can see it already
@dusky chasm the support of f is [0,2] NOT [0,1]
you neglected half of the interval over which you were meant to integrate
wait so if i get a question like this
i should consider what cause idk where you got that 0 to 2
domain
and i think it still gives me the wrong answer cause the answer is one
yes
yeah
IN GENERAL the expectation of a random variable is the integral of x f(x) over the entire real line
ie from -∞ to +∞
yes
its just common practice to immediately clip off the parts where the density is 0
since, yknow.
it's 0
have you redone your integral calculations?
it gives me the wrong answer still
what answer do you get?
even when i change the bounds
what answer do you get?
i got 8/3
and again can you show your work?