#help-13
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what have you tried?
try combining them into a single fraction
the term on the right can also be simplified
Cringelord
Cringelord
Cringelord
which simplifies to $\frac{cos(x)(cos^2(x)+sin^2(x))}{cos^2(x)}$
Aram
do u know what cos^2 +sin^2 is
yes
so you can simplify that
yes
you factor cos(x) like you would factor x^2+x = x(x+1)
@opaque mantle Has your question been resolved?
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Hello guys! How can I show that the following limit exists:
HeyMilkshake
by using the formal Limit definition:
HeyMilkshake
By evaluating the limit across some directions, anmely y=x, x=y, y=mx, x=y^2 and y=x^2 I have the candidate L=2
so I plugged everything in the definition and ended up with:
HeyMilkshake
now, How can I construct inequalities such that I can prove that:
HeyMilkshake
you might want to go into polar coordinates
I would look into rationalization here
so, maybe multiply the left side by the conjugate to simplify?
maybe that leads to somethign easier to prove?
How didn't I remember that. lol
$$\frac{x^2 + y^2}{\sqrt{x^2 + y^2 + 1} - 1}$$
$$ = \frac{(x^2 + y^2)(\sqrt{x^2 + y^2 + 1} + 1)}{x^2 + y^2 + 1 - 1}$$
$$= \sqrt{x^2 + y^2 + 1} + 1$$
King Dedede
but I get it
😄
Happy to provide you with a refresher. I think that I can handle it form here
many thanks!!!
Here's a 🍺 as appreciation
No problem!
I'm still in school 😂
I will have to wait a few years
11th
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Thanks 
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just substitute i guess
hint: the starting value of f(x) (in this context) occurs when x = 0
do you know what (0, 2000) represents?
if the graph of a function f(x) passes through a point (a, b), then b = f(a)
No
damn
well k is right
so you should have $f(x) = 2000b^x$
sills
but idk the base
no it's right
but
you have written it in the wrong form
idk why did you even write it in that form
but k still is 2000
thats the way I was taught
also can you explain how you got this
post your work ^^
f(0) = 2000 ---> C = 2000
thats what I am doing
So now f(x) = 2000*exp(kx)
f(2) = 20
20 = 2000*exp(2k)
1/100 = exp(2k)
ln(1/100) = 2k
ln1 - ln 100 = 2k
k = (ln 1 - ln 100)/2
= (-ln 100)/2
f(x) = 2000 * exp( (-ln100)*x/2)
@violet rapids
@fallen solar
I need help finding the base
now just do the same thing, except instead of using exp, just consider an arbitrary base b
exp() function is just another way of representing e^x
and instead of that, do b^x for some base b
you have to find that...
do you understand why f(0) = 2000 and f(2) = 20?
20 is the base?
no
not really
how did you use that in your solution then
yes
Im not guessing
20 = 2000b^2 is 0.1, -0.1
@violet rapids
1/10
@upper basalt Has your question been resolved?
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I can help, but I thought this was a math discord?
@grizzled rivet Has your question been resolved?
whoops
i forgto about tht ol
I've seen physics problems here, engineering problems
But not biology before
damn
Also, it has to do with the definition of species
not even that. Thought it was one of those questions
the question asks the utility of genetics for classification, tricky
I mean here it is a reductio ad absurdum
I could only eliminate the 1st answer really, the rest could be correct
I'd be mad if I got a question like this
not sure
<@&268886789983436800>
bruh
This is not math
mathematically if you count there are 5 mutations
exactly
and u have to COUNT the differences
so it has math
add me in case i get banned lol
that should help, but the rest is theory, can't really help with that
@grizzled rivet Please go to any number of biology or general homework help servers instead of asking it here
You're more likely to receive help and you wont be cluttering up the help channels that way
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A point on the terminal side of Angle0 has the coordinates..... Where is angle0? is it center or is that the coordinate?
could you post the full problem?
yes I can
I just want to verify that I am answering the questions based off the coordinate given as Angle0
@lunar cave Has your question been resolved?
@lunar cave Has your question been resolved?
I figured it out
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yeah, i think they meant the limit to go to 0
someone probably copy/pasted and forgot to fix it
Yea
alright
I've found a few mistakes in this book before
That makes sense
thanks a lot!
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I need help with 26 e).( it’s not a test, it’s a resource from Nelson.net)
if you don't mind me asking, what have you yellowed out here
A bunch of numbers for confusion
For the question
So any idea of how I would do the last part e, I’ve done the rest
?
@warm vector Has your question been resolved?
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Confused
Basically:
-
Plug in x = -2 into h(x) = ax^2 + 1
-
Replace h(x) = h(-2) with 21.
You can then solve algebraically for a
why'd you replace x with 2 and slap a negative in front of a
Remember:
Example: If t = -4: t^2 = (-4)^2 = (-4)(-4) = 16 ≠ -t^2 = -(-4)^2 = -(-4)(-4) = -16
@plucky dirge Has your question been resolved?
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how do u do this
<@&286206848099549185>
What's the slope of x + 2y = 0?
1/-2
Very nice. Now for the tougher question, when does that curve have slope -1/2?
That is, for what values of x does dy/dx = -1/2
I'll back up a bit. Can you calculate dy/dx of that curve?
Very nice! So note that you care about when dy/dx = -1/2
As that would be the same slope as the line
So you care about -1/2 = -1/2y
ahh ok i got to this step when i was going over the question and then didnt know what to do after
cuz i isolated for y and got y = -1/4 but i have no clue what to do w the value
So I thought you meant dy/dx = -1/(2y) as that would be correct
Then the solution to -1/2 = -1/(2y) is y = 1
So the point that we are looking for has a y-value of 1! We are just missing the x-value
OHHH
yk what i did
i thought the question was asking for perpendicular so i subbed in 2 instead of -1/2
and then got y=1/-4
Kek yeah that makes sense
lol ok so w the y-value, do u just sub it into the original curve to get x?
o ok i have figured out the answer
tysm!
@gentle ore Has your question been resolved?
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How was the integral of sqrt(1-y^2) with respect to x from 0 to sqrt(1-y^2) evaluated here? When I found the indefinite integral, I got this, which is not nice at all:
fuguehoppy
^ The result of my indefinite integral
Oh wait, I see, it's completely constant with respect to x
Oops lol
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Help: When a number is increased by 20% the result is the same when it is decreased by 10% plus 12. What's the number?
Please don't occupy multiple help channels.
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test?
Looks like hw
<@&268886789983436800> :(
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hello
this is a simple one
how do you denote an integrated function
as in derived funciton is f'(x)
@glad halo Has your question been resolved?
What?
Do you mean how to denote an integrated function of a derivative function?
@glad halo
$\int f$ is fine
riemann
riemann
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I’d assume it’s vectors
The lesson is related to forces
Yes it is
Unfortunately, I’m doing vectors next chapter. So I can’t help
Sorry bro
There are smart people here tho, so don’t lose hope, someone will help
We help with the problems but not give answers, that’s the policy
😑
What have u tried so far?
Actually, let me try doing it
U can also use the website cause I’m prob gonna be wrong
Depends on the country
We study vectors in yr 11 advanced math or year 11 physics
Idk about the USA, I don’t live there
Yea
No
I’m in 10th as of now
But I’m doing yr 11 content
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Closed due to the original message being deleted
I was trying to solve problem 11 but had issues on solving for the transient solution
The steady periodic (or particular) is correct according to the answer key, but the transient is wrong
Im sure the solution for y is correcg because i checked it online. So now when im solving for y_c my values for C1 and C2 are incorrect
Differential equations is such a pain dude i hate this class
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oh
Ansh
so uhh, $x(t) = e^{-2t}(c_1 \cos t + c_2 \sin t)$
Ansh
and the particular soln. would be 
this is the correct problem but my work was on a diff sheet and yeah i also got that for the general solution. the particular would be -(1/4)cos3t + (3/4)sin3t
converting that to amplitude angle form and get y_p = 0.7905cos(3t - 1.8925)
which matches the solution in the book
yeah the steady periodic solution is fine but i am having difficulty with transient
solving for C1 and C2
in this equation
$$x(t) = e^{-2t}(c_1 \cos t + c_2 \sin t) + \frac{1}{4}(3\sin 3t - \cos 3t)$$
Ansh
oh
lol yeah ill try maybe i can solve
oh
x(0) = 0 => c_1 - 1/4 = 0
x'(0) = 0 => c_2 -2(c_1) + 9/4 = 0
And you get your values for c_1 and c_2
enjoy
yeah that gives the correct values for c1 and c2
and now the solution is the same as the one in the book
thanks ansh
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can anyone help me with this please?
Hmmm
If I tell you the angle $\theta$ can you find the coordinate?
CatHashira
If I just told u theta then do you know how to find the coordinate?
Uwu yeah
ill try 😭
Ya I don't wanna give the total answer
just help him/her figure it out
You don't have worry about fishing theta now
If I give u this angle how will u find the coordinate that's all
mmmmm
then is the coordinate for point e like (5, cos ((pi × r)/2)/7) , (5 sin ((pi × r)/2)/7) ?? :0
Umm I said ignore theta
Just if I say angle how to find coordinate
Yea u right ig
But u made a typo
Or something u wrote three components
Also multiplied sin by 5
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hello good morning or good afternoon I have a question : Why is the terminal side in trigonometry inside the unit circle always positive
$sine = \frac{y}{\sqrt{x^2+y^2}}$
$cosine = \frac{x}{\sqrt{x^2+y^2}}$
$tangent = \frac{y}{x}$
in quadrant I, x and y coordinates are both positive, therefore sine, cosine and tangent will always be positive in quadrant I
exploseph
since r^2=x^2+y^2 so r=±sqrt(x^2+y^2) why r need to be positive
let r be the terminal side
x be x corr y be ycoor
okay nevermind 😄
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How will you solve word problem on composite figure?
Help
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Do u guys do 4th grade math?
Nvm
What's your question?
Well I'm not in fourth grade so I'll let you guess
They haven't closed the channel
@cedar shadow Has your question been resolved?
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What is two and one fourth times eight fiths?
Not eight fifths. I meant 5 eights
Sry
I'm interpreting this as \[ 2 + \frac14\cdot\frac85 \]
convert to improper fractions and proceed
oops
Lance
2 1/4 X 5/8
.
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<@&286206848099549185>
- Find the inverse of f
- Find dom(f^(-1))
i'm not sure how to do that
I mean this is probably not the fastest method nor would it be worth one mark, but you can find the domain of the inverse function, because the range of the original function is the domain of the inverse and vice versa
uhh sure lemme try
In other words
i dont know the domain either
Wdym
ok wait let me backtrack
The domain of...?
Ye
Do these following images not make sense to you?
Okay well
In simple terms
they do but im struggling to apply them algebraically
ok now subtract -6x from both sides
Okay your objective is to get the variable you're solving for on the same side
either the RHS or LHS
then factor that variable
because you'll have the same variable in same expression on either side
alright give me a sec
alright if i'm not responsive let the other dude take over cause atm i'm cooking
ok
ye that's alright
but
why'd you subtract -6x?
all you had to do then was divide 3x+2
So now you have y=(1-6x)/(3x+2)
ye
that looks good
wait
no
how'd you manage to simplify that
I mean well certainly you could divide
but not like that
if that term is undergoing addition or subtraction you can't cancel them out or anything
alright yea so just leave it in that form of 6x and 3x
Ye
now to find the domain of that function...
But we'll leave it as a single fraction
Ye
Well look at the form you've gotten
It's a fraction
just recall your indeterminate forms
ye
And when it comes to radicands it can't be negative
there
thanks a ton for the help man
what's xEr?
binary operation E?
x belongs to R
yes
is that the official way of doing the does not equal to?
$x /neq -2/3$
!= is taken from computer science
meaning not equal to
\neq in latex
Use \neq
x\neq-\frac23
taemed
Go check #latex-help #latex-testing if you want to learn how to latex/tex
which would be beneficially when doing maths
sure
or anything really, music, natural sciences, etc
idk what latex is
$f(x) \neq -\frac {2}{3}$, $f(x) \in \mathbb{R}$ since it's the range you also have to go back to including f(x)
I could explain the basics rn
I can't believe you've done this
So you yeah may express your range using inequalities or interval notation
i prefer using interval notation
Thus
For a function f:X->Y with domain X we denote the range of f using ran(f) or Range(f). This may also be used to denote the codomain (set of destination/target set) Y.
But of course in our context we're using it to denote the image set of our function
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. is the cmd prefix for @cedar kiln
You there?
@opaque gull
@opaque gull Has your question been resolved?
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Hint: Complete the Square
ah dammit
i forgot how to do that
what is the advantage of completing the square versus other methods of solving the equation
ok yes that is true
The advantage of my hint will be obvious when you apply it
you factored p(x)
f(x) g(x) h(x) are factors of p(x)
i dont understand what you're getting at
ok...
feel like there's an obvious connection im missingf
but i can't think of anything
fgh(x) = f(x)* g(x) *h(x) =p(x) = (x + 2)^2 -15
ok now how do i figure out what each function is
find 3 functions that multiply together to equal
p(x) = (x+2)^2 -15
but they dont multiply they get composited
i have to find functions that you can plug into each other to get that
i have the answers so don't worry about giving it away
i just want someone to explain what's the process behind it
if it were composite it would be f(g(h(x)))
wait f g h are multiplied together?
must syntax error then in the original question, but makes sense
So yes, Mosh' suggestion works
complte the square
Then can you see how the answer works?
i cannot
i do
9 permutations, learn by trial and error
but the logic of figuring out what functions compose into that is hard to comprehend
actually 6 permuations
given the answer given
this is some next level explaining
f(x) = x+1
g(x) = x-1
h(x) = x^2 + 4x - 11
Surely this works
And yet the mark scheme is very specific
i think it's more geared towards testing the critical thinking that you described above
First thing that came to my mind
it could be that the class teaches a particular method to achieve a specific answer?
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What have you tried
dont know where to start
What formulas do you know that are related to quadratics?
Write them all down
See if any are helpful
completing the square
factorization
quadratic formula
Any others?
what is completing the square used for
creating a perfect square no matter the quadratic?
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
$$f(x) = a(x-p)^2+q$$
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
What's the point of this process?
i don't know
$(x-p)^2$
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
uh no...
If I have a square number
the square of something
what must this always satisfy?
$k^2$
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
No matter what k is?
im stumped
hmmm
What is a negative times a negative
a positive
You can say something about all the y-values here
just take a derivative
they go infinity but the min is 0
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
Does this make sense now?
haven't taken calc yet
ah ok
Yea I figured. Shuri's giving great hints
so lets backtrack
x is a variable
p is a constant
but its still something squared
It must be non-negative
yes
So does this tell us something here 🤔
If you want, you can work with inequalities
$$(x-p)^2 \geq 0$$
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
so bracket must be positive
right. (or 0)
yes
what about a times it
a bit of a tricky question but maybe u can figure it out
A hint is there is no fixed answer --- it depends on something
a p q
is that what you're getting out
are all constants
ah this is in vertex form
a could be a negative
the signs inside the parentheses switch
no...
it comes negative
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
is =2
The minus outside doesn't affect the sign inside the parenthesis
(the sign inside goes away because square)
yes
So the squared term is always 0 or positive
If you multiply by something negative ... ?
it becomes negative
it stays positive or 0
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
And then we are one more step from saying something about f(x)
f(x) is the left side add q
Does this make sense?
somewhat yes
So the point of vertex form is to find the maximum and minimum of a quadratic
(also known as the extremum)
The last thing to check is when the maximum/minimum happens
If you reverse the steps
You should see f(x) = q (the minimum or maximum)
When this original squared term is 0
yea im lost
👌 which bit
here
check this inequality
I claim q is the minimum if a > 0
the maximum if a < 0
Plug in some numbers for ^ if it doesn't make sense @opaque gull
$$g(x) = (x-1)^2+2$$
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
It's the equivalent of parabolas opening up or down
We have 'something positive or 0' plus 2
yes
The smallest g(x) can be
2
is when the 'something positive or 0' equals 0
If the square equals 0
we have x-1 = 0
So I can immediately tell from vertex form
(1, 2) is the minimum in this case (since the coefficient of x^2, a = 1, the quadratic is a u-shape)
yep
so that's the point of the vertex
👌
why not -1
for x?
x = -1
gets me
(-1 -1)^2 + 2 = 4 + 2 = 6
I want the bracket to be 0. So I solve x - 1 = 0
$$h(x) = -2(x+4)^2+5$$
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
So quickly try this to make sure you got it
Find the coordinates of the extremum of h(x)
and determine if it is a minimum or maximum
minimum is -4, 5?
yes
no
(-4, 5)
not a minimum
(x+4)^2 is always non-negative
So -2(x+4)^2 is always non-positive
maximum since its opening downwards?
yes
So to begin the question, you should be able to deduce something from the 2nd sentence using vertex form
so the graph is upwards opening and the minimum point is at (-1.5, ?)
yea
Standard form
$$f(x) = ax^2+bx+c$$
Vertex form
$$f(x) = a(x-p)^2+q$$
Factored form
$$f(x) = a(x-r)(x-s)$$
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
^ these are the forms you need to know in general (the letters other than x are constants)
alright
i thought the question was referring to plugging -1.5 into the x of the equation
so that threw me off
but it seems like i was supposed to convert it to vertex form for it to make sense
Also remember the x-coord of the minimum/maximum is always exactly halfway between the x-coord of the roots (if they exist).
yea
AH
GOT IT
YES SO HALF THE 9
IS 4.5
and when added to x demonstrates that roots are at 3 and -6
Oh I just noticed you don't need vertex form then lel
But it definitely is helpful for a good number of Q's
yes i have encountered it alot
ok so now question b
should be intuitive
since we know all the values
q is -1.5
but idkt he r
Notice all these 3 forms must be equal
You can convert either of the bottom ones to standard form and equate coefficients
equate coefficients?
$$f(x) = 2x^2+(k-3)x-44$$
$$f(x) = (k+2)^2x^2 + jx - s$$
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
wait
𝐒𝐡𝐮𝐫𝐢𝟐𝟎𝟔𝟎
I chose a bit of an extreme example
If these two are the same quadratic
we need a = 3, b = -5, c = 2
Otherwise they will be different
yes
The same applies here
x is a variable, the rest are constants
And finally the same applies here
If you multiply out the vertex or factored form
yes each one has three constants that correspond to a b and c
@opaque gull Has your question been resolved?
@opaque gull Has your question been resolved?
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Hi
im only doing the odd ones but im not sure about 1 and 3
how would I find when the tangent line is horizontal
well what does it mean for a tangent to be horizontal
what slope does a horizontal line have
0
what's dy/dx
f'(x)
are you in calculus
yes
or precalculus?
calc
what
so I find the derivative of f(x)
and set it = 0
cuz we wanted the slope of the tangent line to be horizontal (0)
then solve ?
yes
oh and then those should be the answers?
Do you understand what f'(x) represents
yes
if you do, then you should be certain that these are the answers.
no not just that
oh
f'(a) represents the derivative of f(x) at x = a
oh yea
Geometrically, it also represents the slope of the tangent at x = a (or you can say at the point (a, f(a)) )
at a certain point (a)
yea
oh shoot sorry I gotta go. Thank you for the help guys
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Hello, I have no idea how they went from the first one to second one, could anyone help explain to me what did they do here? Thanks in advance!
Are you familiar with
root(x) = x^(1/2)
3rd root(x) = x^(1/3) ?
you can break out 1/x^(1/3)
and that is equal to x^(-1/3)
(it's generally true that a^(-1) = 1/a)
does that make sense? i'll explain the rest, just making sure you're following so far
yep yep
so then we get x^(-1/3)*(x^(1/2)-2)
let me format it better so you can see it easier 1 sec
okay!
,, x^{-1/3}(x^{1/2}-2)
PixzleOne
does that make sense too?
,, \frac{x^{1/2}-2}{x^{1/3}} = x^{-1/3}(x^{1/2}-2)
PixzleOne
👍
PixzleOne
PixzleOne
no worries! good luck have fun :)
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So the objective was to find p and q
Constants
Did I do it correctly?
<@&286206848099549185>
could Q posibly be 9 actully if I messed up my -/+ signs?
@azure magnet Has your question been resolved?





