#precalculus
1 messages · Page 309 of 1
What are trying to show?
Trying to show what you have is equal to something?
Try what I suggested.
You need end up with something nice.
okay
Not sure how I do that
Observe you have sinx/cosx + cosx/sinx.
Yes
What should you do to get sin^2x + cos^2x?
Multiply?
Yes.
And divide all that by 1/sin^2x
Yes. Also what does sin^2x + cos^2x equal to?
Huh? That is not right.
how would I add that
Try to recall pythagorean theorem.
Then divide?
Yep.
So what are you left with?
sin x cosx
Did I divide wrong
Yes sort of.
what did I do wrong
a/b * c/ d = ac/bd.
Oh yea
That is how I got that up top.
Btw for this it would be sinx * sinx / cosx *sin x
Right
Yes.
Tanx?
So what is the final answer?
Yes.
Not sure how your teacher got 1, unless they evaluate tan(x) at x = pi/4.
Hmm 🤔.
Ok I don’t see anything wrong with his solution.
I can’t seem to find anything wrong with ours.
Checking again.
👍🏼
@mental steeple I found his error. In the last line tanx from previous line is not equal to sin^2x/cos^2x.
Yea I saw that to
Not sure where he got the cos2x from
And sun
sin
So we are right correct?
Yes we are.
Nice I’ll tell my teacher about it rn
The 2 confuses me for this one
Expand what each trig function means.
?
Like express it in terms of cos and sin.
Ik that cot^2 = cos^2x/sin^2x
Yes.
What about csc^2(x)?
1/sin^2x
Ok what do you do think we should do now?
Divide?
Yes.
2Cos^2x
Close.
It should be cos^2(x)/2.
Next time be patient and work it out first before asking for help.
Just the 2 threw me off
Otherwise it’s easy
Also quick question if something was 1/cos^2x + sin^2x / cos^2x would that equal 1+sin^2x / cos^ 2x = cos^2x /cos^2x = 1
Yes you can add it since the denominator are equal. Generally a/d + b/d = (a+b)/d. But 1 + sin^2x is not equal to cos^2x. It’s 1-sin^2x = cos^2x.
It follows from sin^2x + cos^2x = 1.
Okay ty
you guys got a good math problem?
I need some help evaluating a problem(top of the page)
When I can evaluate it jn 2 different ways(right and left side) I just don’t which one is correct
Btw I just graphed the angles at the bottom of each one
This is the correct picture
My bad
Note that tanx=1 happens for x=kpi+pi/4, and those x also give sinx=±sqrt(1/2).
However on the left-hand side you also get some spurious solutions caused by the squaring early on -- that is, x=kpi-pi/4 also gives you sinx=±sqrt(1/2) but don't satisfy the original equation.
wait the x values also give it as +-?
I thought it was just positive
oh wait nvm forget that
ohhh ok this makes sense now
thank you
let me try that
thanks it worked
question, how many point(s) does a tangent line intersects a curve of a function?
You need to figure out exactly what "intersect" means to you first. Of particular relevance: Does the point of tangency automatically count as an "intersection"?
What does p represent in the way of graphing conics in polar equations represent?
ep/1-ecos(theta)
Does anyone mind helping with a hw problem?
\
this is the math problem
when I factor it I get 131^2 k^2 t^2 -168t+48
17161+k^2 t^2-168t+48
my professor said I need to use the quadratic formula for this problem
But I'm still very confused
@brittle ice do you still need help with this
yeah
if $z$ is such that $p(z) = 0$ then what is $p(\bar{z})$?
Ann
hello, Im confused on this question. Is there an identity to use or something?
Use properties of conjugates and the definition of a polynomial to show that $p(\overline{z}) = \overline{p(z)}$
Eevee Trainer
i was addressing this question to jef
Just figure out the θ that makes the first equation true, in the fourth quadrant. Then find sine & cosine of that angle
Oh sorry 
In particular perhaps consider using inverse tangent
is this all the topics that should be covered in pre-calc?
deciding on if I should use these lessons or this one https://www.youtube.com/watch?v=FkUEsP9efFg&list=PLDesaqWTN6ESsmwELdrzhcGiRhk5DjwLP&index=2
Support: https://professor-leonard.myshopify.com/
Cool Mathy Merch: https://professor-leonard.myshopify.com/
What Functions are and how we can determine when a relationship is a function and when it is not.
this one seems like the better course to watch right
Hii can anyone confirm if this is correct
I think you want to check (i) again
Oh
The second one I think it might be is 2 because it matches based on the y-axis Bht it’s also similar the choice answer #1
?
Like it could be choice two but idk the difference between choice 1 and 2
You need to know the difference between (i) and (ii).
In (i) x approaches -4 from the left
In (ii) x approaches -4 from the right
Usually system of equation, partial fraction decomposition, trig is covered in precalc. At least where I am from.
Need some help, I can send an image of the work
Domain and range of relations and functions
Lemme see if I can help, is it ok if you send the image regarding the problem?
Hello, I wanted to know what I should know to start deriving functions?
great series to watch to help understand calculus
differentiate
I'm pretty sure what he asked isn't in precalc at all
no i'm pretty sure you interpreted it correctly lol
i'm like 98% sure they meant differentiating
but everyone always says deriving
^^^
pretty sure that's how its called when I started learning calculus.
deriving does not mean differentiating lmao
if you know calculus you should definitely know that
ik
no i did not know the difference by the time I finished calculus AB
pretty sure the former if in #precalculus
Hello, I'm in need of help for a differentiation proving question I'm stuck at, I can send the question and what my working is so far, hoping someone could help me with where I went wrong/where I'm stuck at?
At the side it says k is a constant
is that how I'm supposed to differentiate x²k?
Product rule
Ack... That's all I wrote man, I'm not even sure what I'm doing so...
how exactly did you apply the product rule?
it looks like you skipped stuff and./or didn't apply it properly
and also applying product rule to this is a bit overkill
like the whole equation, I'm supposed to use quotient rule to differentiate it, right? So I took the denominator multiplied by the first derivative of numerator,
but am I not supposed to use product rule to differentiate x²k?
well to differentiate you fraction you could apply the quotient rule
but the issue with what you did is that you didn't differentiate x^2*k properly
you "can" apply the product rule if you want, but you'd need to apply it properly
oh wait
k is a constant
so it's essentially kx² right?
damn I didn't need to use the product rule
nvm I get it now, thanks for the help!!
That's not PREcalculus
Although it's differential stuff, I am happy to help. Why don't you try to differentiate it partially,if you know. Otherwise, I can give you a solution. I think the answer is a set of points which satisfy the condition above.
Good to know
thanks
No problem:)
$P(X)$ is a real polynomial such that $P(X+1)-P(X)=X^{2022}$. Prove that $P(2/3) \geq P(0)$.
erictheeonicpizhao
how do i do this?
<@&286206848099549185>
do i find the magnetitude of each vector?
What is it asking for
it diodnt specify
is this about finding the discriminant?
To locate a whale, two microphones are placed 6000 feet apart in the ocean. One microphone picks up a whale's sound 0.5 second after the other microphone picks up the same sound. The speed of sound in water is about 5000 feet per second.
a. Find the equation of the hyperbola that describes the possible locations of the whale
b. What is the shortest distance that the whale could be to either microphone?
ig draw a diagram but i can't visualise
still need help?
yes
ok could ya get the diagram?
i'm literally going to sleep
ok so 😂 how tf do u do this 😭 maybe im just not getting it but why is the f(x)= equation so huge ??
this is an example I got from trying to solve a hoemwork questions but I don't understand the instructions
f(x) in the explanation is a general rational function, a polynomial over another polynomial
the goal is to find the horizontal asymptote, if it exists, or to say one doesnt exist
to do this they are splitting the general rational function into 3 cases depending on the degrees of the two polynomials that compose it
so 18/(4x^2 + 5) is case (1) where the degree of the numerator is less than the degree of the denominator
A spherical zorb with a radius of 1.5m is being filled with water at a rate at 100π cm^3/s. At what rate is the height of the water increasing when the water is 20cm high??
Need HELP!
you may wanna try any one of the math help channels
cheers
still need help?
i believe the area of the circle in at 20cm is .56pi m^2
or 56 pi cm^2
and (100pi cm^3/s)/(56pi cm^2) = 25/14 cm per second
if ur wondering how i did this i used Pythagorean theorem
woah
?
your handwriting is terrible
from what i gather the radius is 1.5
i was writing on notes on my phone 😆
i am talking about radius of the circle cross section
at the waterline
the length of the chord?
idk damn know
🤨🤨
Besides that being a very recognizable ratio, the interval of [0, 2π) is nothing special.
What do you mean by which quadrant? You mean to physically draw the triangle?
no, after you get the inverse you are supposed to figure out what quadrant it came from
cos^-1(4/5) = 0.64
then you need to find the reference angle
but idk what quadrant equation for reference angle im supposed to use
answer in the book iis 1/56cm per second
idk how that's possible
ru sure
it should be 100/56 cm
or 1/56 m
it says the interval 0-2pi so it's all 4 quadrants
AstroRP
How do I partition this?
you can't, unless you're willing to go into complex number shit
this is already an elementary partial fraction though
and how would that look like
because wolframalpha doesn't show anything (real or complex)
$\frac{1}{(x-2i)^2(x+2i)^2}$
Ann
,w partial fractions 1/((x-2i)^2(x+2i)^2)
it gets something done
i guess you'll end up with complex logarithms which are going to be hell to work with
but it gets something done
ah nice ty
Friend was doing sequences, find explicit formula
$\frac{-6}{5}, \frac{7}{15}, \frac{-8}{45}, \frac{1}{15}, \frac{-2}{81}, \dots$
! Brontochad (RYC4blushysully)
...19, 19, 19, 19, 19, ...
Turns out if you write the bottom as a geometric sequence it works super nicely
1/15 = 9/135 so it continues the arithmetic sequence on top
hello
i am new
i was bored today so i made piecewise functions with a single equation
it doesn't support >=, <=, =, or != in the domains though
you know desmos can already do that, right? :P
{condition1: formula1, condition2: formula2, ...}
some of the issue appears to be in your handwriting, which messes up the equation(s) you're working with
also plugging things in incorrectly in some places
just in the first line alone:
- why does the
-bterm appear not to be part of the fraction? the fraction bar should extend clearly to cover it. - the stuff under the root is b^2 - 4ac, which in your case should be 6^2 + (-4)(9)(7), not 9^2 + (-4)(9)(7) as you wrote.
it all went downhill from there
lol
ok
Where am I going wrong @willow bear
Hold on
.
read this again
I didn't see it lol

why are you doing math at 4 in the morning
quiz?
we won't do your homework for you.
ok then posting this here is pointless
everyone here has their own problems to deal with
nobody gives a shit about yours
after b^2 it should be - not +
war was here
b&
thank you
guys can you reminde me by the binomial theorem ?
$(x+y)^n = \sum_{k=0}^n \binom{n}{k} x^{n-k}y^k$
Ann
$what do \binom{n}{k} mean$
MRme001
binomial coefficient, a.k.a. "n choose k"
$\binom{n}{k}$ is defined as $\frac{n!}{k! (n-k)!}$
Ann
thanks
in the function 4/(x^2+x) why is there a graph under the x axsis?
i understand that x goes to ifinity when x approches -1 from the left and 0 from the right
i think it is because x is defined between -1 and 0, should i take the derivitive and look for when the derivitive is 0 to determent when x is defined between -1 and 0 ?
it's part of the same graph, the function is just negative there
should i take the derivative and the look for max point to determine when that part of the graph starts?, in this case its -16
do you mean the highest point of that part?
if so then yes
...your phrasing is hard to parse
yes
yea im not the best with either math terms and explaining math in english, but thanks for the help!
drawing 1/4*(x^2+x) might help u visualise that graph
that's a reciprocal of parabola
ill try thanks for the tip
zeros of this graph will be a vert asym of the reciprocal graph
and loc min will become loc max
hence the "max point" of that particular part
cuz u can't divide by 0 so it will be undef so asym
cuz as y becomes larger, the reciprocal becomes smaller
thanks for the help, ill keep that in mind
missing parentheses
⬇️ 
I don’t know how to prove this, can someone help ?
i don't think that's precalc
are you sure this is correct ?
If you multiple the square root by M
the M^2 is canceled out, leaving you with
$\sqrt{P^2+4\cdot{pi^2}\cdot{n^2}\cdot{M^2}}$
and as M approached infinity, this entire expression does the same
Deus_Vult
Ok
i guess it applies to any math, but i’m in precalc rn.
does undefined = undefined? or does it not equal anything bc it’s… undefined
technically the word 'undefined' has no business showing up in a proper equation
but people do it all the time in math classes and it's understood what they mean
like there will be a function, say f(x) = 1/x
and people will write "f(0) = 1/0 = undefined"
what they really mean is f(0) is undefined
1/0 “is” undefined, but not that 1/0 “is equal to” undefined
right
i’m solving trig equations and such and i’m checking my solutions. and i had to find out the cot of pi
so it popped up in that context
cot(pi) is undefined
sometimes people may write cot(pi) = undefined, which is sloppy, but it's generally understood
wait let me write out what i remember
cos^2(pi) * cot(pi) = cot(pi)
would those two expressions equal each other?
I see
I mean, both sides are undefined
I see the point is you can erase cos^2(pi), since it's 1
but you could even just say "cos^2(pi) * cot(pi) is undefined" and stop there without using an equation
would they equal each other though
that’s all i’m worried about because my math core was on that
same exact problem
I assume they mean for you to say yes
OH THANK FUCK
kind of a sketchy problem though
yea i may have solved it wrong but i checked it over twice
unlikely but very much possible
is precalc hard learning it for the first time? I'm in algebra 2 right now and I hear it's like a whole new concept in math so I wanteed to hear other people's opinions on it
nah it's not bad
precalc is pretty easy
calc is the first bit of real actual math you get to see
algebra 2 or precalc which one do you think is harder learning for the first time
equal tbh
precalc builds off algebra 2 just like algebra 2 builds off algebra 1
again, calc is where you first see math
alr cool thx
precalc has the unit circle and common trig values, it can be a lot to take in
trig makes sense as an extension
he'll be fine
it's not bad
as long as you understand em
and why it works the way it does
hm fair
i don't remember anything from trig because it was during quarantine and I was playing valorant during all the zoom classes...
damn
some students find all the factoring degree 4 polynomials and crap from algebra 2 harder than anything in precalc
really depends on what you're stronger in
gods i forgot we had to do that lmfao
same concepts, different lingo
learning sines, cosines, csc, and all that jazz is like learning a new language but once you get the hang of it, it’s super easy
👍
is fifth degree polynomials in precalc?
not really, but algebra 2
i do not remember learning that in alg 2
oh wait, p’s and q’s and synthetic division?
they even do descartes' rule of signs
i wish i'm that one kid in the back of class that pays no attention in class and is always watching youtube videos in class but still somehow knows all the math and is a genius
it's done because you have to guess a root, and you might get unlucky and not try the right one until the last possible one
used to be me until this year
same for me
possible but would take some trial and error
i dont even know anything about calc but i already hate it
my friend’s taking it rn and she said just know the unit circle by heart
Basically this question asks me to find the vertical intercept and I'm wondering if I solved it properly using this equation that I did here.
Answer is b = 8,000
Is the second of your images part of the problem or your answer?
Can you state a concrete formula for profit as a function of items sold?
Plug 2000 and 3000 into that and verify that you get 24000 and 32000 out.
It's better to learn how to derive or recall it again and agaon
Learn quadrant one, there are three values, 1/2, sqrt 2 /2 and sqrt 3 / 2
the pi values in quadrant 1 are more obvious on inspection. Add pi to move half a unit circle to quadrant 3, add pi/2 to move a quarter a unit circle to quadrant 2
true true
brooo
its 1am
and i just got to vectors
and this shit is tripping
like, why i gotta find out how to represent it in how many one unit movements it made
you don't "gotta" do shit if you're so repulsed by it
but this is the decomposition of a vector in the standard basis
and especially in linear algebra one is often interested in looking at vectors through a different basis than the standard one
to say it in a highly abridged manner that skips over most of the details
not repulsed, just dazed and confused xD
because think of the cartesian coordinates as an incomplete quantity and you want something to tell you about the direction of functions and curves
what are all the topics i have to learn before studying precalulus?
i learned trig
what about exponentials
are polynomials used in precalc?
how
ok
how advanced should my polynomial skills be?
what does 3rd degree include eg. algabraic geometry
simplifying dividing and multiplying then i can move on to precalculus?
ok thanks i might be able to do that in a couple of days
no prior knowledge tho
possibly
thanks
ik what to study now
I have this complex analysis problem but I'm pretty sure it's just a geometry/precalc problem about hyperbolas. I have $z\in\mathbb{C}$ where $z-1=r_{1}e^{i\theta_1}$ and $z+1=r_{2}e^{i\theta_2}$. I need to show the region described by the conditions $r_1 > 0, 0 < \theta_1 + \theta_2 \leq \frac{\pi}{2}$ is the region between the unit hyperbola $x^2 - y^2 =1$ and the x axis in the first quadrant. I'm stuck showing how z satisfying the constraints involving $r_1$ and $\theta_1 , \theta_2$ imply z is in the region described above, I think I see how to show the opposite inclusion.
DootDooter
Geometrically we should have something roughly like this:
The last thing I could think to try was to solve for z in terms of $r_1,r_2,\theta_1,\theta_2$ and then try to sub into $x^2-y^2\geq 1$ looking for some nice angle relationship.
DootDooter
That got me here:
Assuming I didn't make some super dumb algebra or trig mistake, which I might have because my brain is currently kinda fried.
But I don't see any nice relationship that is useful from here. If anybody sees any way to proceed ping me.
Wait maybe I see it
$z+1-(z-1)=2$ so $r_2 cos(\theta_2) - r_1 cos(\theta_1) = 2$ also. So, $r_1 r_2 cos(\theta_1+\theta_2)\geq 0$.
DootDooter
Pretty sure picking theta one and two in the interval I need and reversing my steps in that last image will get me the identities that I need. 
ok sorry
ask your question, just don't ask to ask
hey guys do you mind helping me with the one i got wrong? (i got my answer for the 1st one by doing <340cos40, 340sin40> )
the wind is blowing southeast while your vector is pointing east
$$ \begin{aligned} &y \geq-2\ &y \geq x+3 \end{aligned} $$
Anyone here know how to solve this problem? I don't understand how to solve it.
if u take the natural logarithm of e^anynumber, theres a power rule that allows u to cancel the e and move the exponent down
so take ln of both sides
look at the top example
so u can just ln both sides and isolate x
Alright thanks for the help
i am gonna study logarithms
i am a begginer but i do however know the very very basic concept such as what the function does
could someone give me recommendations on what to learn
what grade are you in?
i would suggest getting a strong understanding in normal algebra first
like use khan academy or some other source to learn basic algebra then move on from there
anyone have other alternative step-by-step solution without prior knowledge of L'Hospital Rule?
I want to know why that limit become natural logarithm, using theorems and such
zoomed in graph can show me the value, but still not satisfied with that one
This is what they had. We have an indeterminate form of 0/0 when we take the limit as x->0. So taking the derivative wrt x for the top and bottom of (2^x - 1)/x we have it's ln(2)2^x. Now take the limit as x->0 we have it's ln(2).
As for an alternate proof, maybe graphing the function in desmos and zooming in to seem what values it's you think it's converging to and the using the definition of a limit to prove the function converges to that.
I can't think of anything else right now.
Have done with graphing proof and i saw the irregular shape after zoomed in the graph. However, the algebraic solution that u told me or from the pic above is kinda recursive. I just curious whether there is algebraic way to solve it without prior knowledge of derivative itself. Assume that equation is just an algebraic equation and as a people without calculus knowledge, i want to solve it just using algebra
Maximum means something with differential. Open your book
for 9a, use the limit definition of derivatives and the derivative law of trigonometry
yeahh what else do u think??
Ohh I got it
if you know what is sec(x) means, then everrything's trivial
ur welcome
let's say I start investing 160 dollars at the start and i don't add anymore money and every week I earn 5% profit, what's the equation for this scenario?
160(1.05)^w where w is every week after investing that 160
Pic unrelated
Oh wait
Are we reinvesting this money
“Compounding interest”
If we are then the equation above is fine
If you're offered an investment that will give you 5% profit each week, it's a scam, no ifs or buts. Run.
its a hypothetical question, wasnt offered anything
Bruh=moment
yeah its compounding interest
Yeah we’re good then, the standard form for compound interest would be a(b)^t where a is the original investment, b is the increase (this number should always be greater than 1 to represent an increase) and t represents integer unit for measuring time, like 2 weeks or 5 months.
can i get a quick rundown on why a certain thing is the way it is? I'm in calculus but ive completely forgotten about sin, cos and tan related stuff
i cant remember how to actually reach this result
apply arctan to both sides
the way you take minus signs out of the parentheses is no good
Wait why isn’t a negative leading term
ManifoldCuriosity
$-(x^2 + 4x) - 5$
ManifoldCuriosity
when you take out a minus sign in situations like this, you have to flip the sign of everything inside the parentheses
Oh I did that
oh I see, you do it in the next step
just so you know, the equation where you didn't do it yet is technically wrong
So I should do it early?
ManifoldCuriosity
Oh okay but I dont think I solved it correctly
you correctly write + 4 inside the parentheses
but then you balance it with -4 outside
which would be right if it weren't for the negative sign in front of the parentheses
I did that because -4/2^2=4
I thought we do that to both add the -4 to both sides
that minus sign in front of the parentheses means you're really doing -4 to your expression
so you have to balance that with the opposite, +4
should be:
$-(x^2-4x+4)+4-5$
ManifoldCuriosity
now somehow you do end up with -1 below that
which is right
but it doesn't follow from what you wrote
in the end your answer is right
but the work has several mistakes
So I got the right answer but my steps are confusing?
yeah
Alr I’ll fix it
you seem to know how to do it, just not written up in a usual way
What if I did it by equaling the equation to 0
you can do it all the same way
Ok Alr Ty
sure thing
fixed some things, but you forgot about x for a few lines
you wrote x^2 - 4 + 4 in the parentheses
instead of x^2 - 4x + 4
also you should have a + before your 4 after the parentheses
Can someone explain this to me?
No
consider looking it up first
Okay so I have to substitute both values in the equation?
yes, (separately)
There is a zero, it goes down, then stop, then goes down
It like this but going down instead
Wait but they are both negative so is there no zero?
not necessarily, depending on the function, there could be a zero in the given interval
the IVT can't be used to conclude that there no zeros
so in this case since both are negative, IVT cannot be used to determine if there's a zero in that interval
It’s an equilateral triangle. You know the angles.
And you have an altitude.
hm
Have you learnt about derivatives?
wait i will give a sum it's impossilbe to do
So you havent been taught what they represent right? And their use?
I have but it’s really confusing to me
if the signs were different, IVT guarantees that there will be at least one zero
otherwise it doesn't do much
the IVT can't be used to conclude that there no zeros
so in this case since both are negative, IVT cannot be used to determine if there's a zero in that interval
You'd have to show that there exists/doesn't exist a zero using derivatives, I can't think of another way
This is in accordance to 
Do you have an example where the signs are the same?
This is the only one that was given
I guess since it specifically requires using IVT your answer is that it cannot be determined then
Oh okay alright Ty
I need help please
“Least productive” should be when P = 0. You should be able to set the equation equal to 0 and solve.
can i have help pls
Can you be more specific?
all the answers that i entered are incorrect
The question is worded really awkwardly, but from how I understand it, most of your answers are correct.
C is incorrect simply because (0, 2) falls on the circumference of a circle with a center at (2, 2) and a radius of 2.
It also looks like D is not asking what it intends to ask. Your answer is correct, but I think there might have been an error with the question.
Do monsters have width?
We can use the IVT to prove that there is a zero in (-1000,0), and that there is a zero in (0,3) and that there is a zero in (4,1000). If we then also know that a polynomial of degree 3 can have at most three zeroes, then arguably we have determined that there is no zero in [3,4] "using the intermediate value theorem".
Can I borrow some help to get this started please?
The ball in is air for as long as there's vertical motion.
The objective starts from y = h_0 and ends up at y = -h_0 finally again, when that happens it's finally not in air.
Use those facts.
I think it’s asking to find whether a point lies within or on a circle given the origin and radius
hey this one has been driving me bonkers, i think i have to use implicit dif/related rates but i’m losing my mind some help would be appreciated
would you like the slightly cheaty but legit solution, or the solution your teacher likely expects from you?
both would be good to be honest
i’d like to learn the proper solution but seeing the cheaty solution could help speed me up on an exam
cheaty: the radius and height of your cylinder are given by r(t) = 5 + t and h(t) = 8 - 4t, and the volume is V(t) = pi * r(t)^2 * h(t) as you wrote. in all this, t=0 is the moment in time that is of interest to us. your goal is to find V'(0), which you can do by expanding out V(t) and applying little more than the power rule.
'proper': same thing except you differentiate V wrt t symbolically, treating r and h as functions of t (which they are) and ending up with a mess of r, h, dr/dt and dh/dt into which you then plug the numbers. no mention is made of any specific point in time
ah thank you
i think my mistake was not interpreting r and h as functions of t
which totally makes sense now but i just got confused since the usual style of questions doesn’t normally give 2 values (ie radius and height) and couldn’t figure out how to apply it
cheers man 🙂
Why do we turn terms into smaller with '
like
x' = (x - 1)
whats wrong with x -1 ?
X-prime, as its called is a way of saying its different but similar to x
x = (x - 1) isn't valid
It’s all a matter of notation
x’ is just a symbol or letter used in math, similar to a or b
And it meaning in use depends on context:
In calculus it usually means the derivative of x
In other places it probably just means the new value of x after some change
<@&286206848099549185>
uhm sry but what is the question asking? I dont really comprehend this
i’ve been given a relation and am calculating the dy/dx using implicit, but it is asking for it in terms of s only how do i find without y?
find dy/dx in terms of only x
that’s what i got
<@&286206848099549185>
sorry for the late response, but you can solve the implicit equation for y explicitly since y>0
@hazy dust
Then, you can either take the derivative of that directly, or substitute what you got for y into the implicit derivative you've already found.
How would I differentiate this?
I need to get a general formula for displacement based on gravity and it's altitude
$\rho(t)$ needs to be substituted later based on the position then
sentinel
Could someone help me with my last few problems, there’s some proving Identitys, a double angle problem, and a few other things
the last term in the denominator is $(\rho(t))^2$ since you're squaring the denominator of the previous fraction.
vin100
What question are you asking? That is just an expression.
There's only sin/cos on the left, so convert everything to sin/cos on the right
why'd you turn sec^2(x) into cos^2(x)
Wdym
you have this in the denominator right?
Yes
I think
does 1/cos^2(x) = 1?
no
so how could you change the 1 so that the denominator is cos^2(x) and would still equal 1
Can’t you do cos2x/1 then cross multiply which the cos2x cancels out then your left with sin2x-1 which equals -cos2x
you mind writing out the work and taking a picture of that?
ok
my mind is dying
:(
would you ever do this?
No
same concept, you can only cross out if it’s multiplication
So we are subtracting right
lookey
Oh I was thinking of that didn’t know I could do that
it’s way harder to figure out sometimes because it’s letters and not numerical
yea, that’s valid
yes yes
Wouldn’t the top =1
yep, for the denominator of the entire expression
Ok
and now it’s just division!
what where did you get the 1/cos^2x
Thank you
Got it
what the kronk is that?
It’s just saying if the graph is at a relative minimum or maximum
yow just a simple question, is integration the inverse process of differentiation or the reverse process?
dunno if reverse and inverse are the same
I don't think reverse is a formal description
They're inverse operations
Though they take functions as parameters not singular number.
(although a constant could be thought of as a function that returns the same number independent of the input)
Is it always the case that if g(f(x)) is one to one this implies f(x) is also one to one and it g(f(x)) is onto then this implies g(y) is also onto? Prove whether the statement is true or not
@viscid thistle if u agree then prove it, if not give a counterexample
The problem is I don't know whether it's true or not .
I feel like it may be true but I don't know how to prove it
u can try getting an idea of whether its true by playing with examples
if ur proving, it helps to unpack definitions (in this case those of 1 to 1 & onto)
Someone can help me with this problem
-3x(2x+3)>-(-3+4x)
-6x²-9x > 3-4x
4x-6x²-9x > 3
-6x²-5x-3 > 0
6x²+5x+3 < 0
Solving 6x²+5x+3 = 0:
D = b²-4ac = 25-24×3 = 25-72 = -47 => x∈Ø => there are no solutions for -3x(2x+3) > -(-3+4x).
x∈Ø.
Should I factor when simplifying
Just look at the last two lines
The answer key says I don’t need to factor out the h but I feel like I should
I mean, doesn’t that make it…simpler?
It depends on what you are doing with it.
If you are finding zeroes, trying to factor saves you time over the quadratic formula.
Especially if one of the zeroes is 0.
- Let "F" be a function of Real variable, defined by f(x)=mx+b /(this bar means such that) 2f(2) + f(4) = 21 and f(-3) -f (1 ) = -16. Find 1/3 f(1)
- If f(x) = ax^2 +bx +c ; f(-1) +f(1/2)= 15/4 ; f(-1)=0 ; f(1) = 8 . Find f(5)
Not doing anything with it. So I guess it doesn’t matter either way.
But yeah I get what you’re saying it would definitely be smart to factor if you are doing pretty much anything with it.
Yeah lol
I think you have learnt This right r.n - a.n
Where r is your general point and n is the normal vector
I don't think my precalc class taught that
what is an?
a is a specific point, right?
Yh
sin^2 x = sin x^2 ???
that is an identity
not an equation
every real number is a solution to that
oh wait
sin^2x and sinx^2 are the same thing right?
unless you mean sin(x^2)
,,sin^2(x) = sin(x)^2
Lidoh
I think that was what was being asked. But it is a bit confusing when you don’t use parenthesis for the argument of sin.
$\frac{a - bx - 16}{\sqrt{3}x(\sqrt{a - bx} + 4)} = \frac{a}{\sqrt{3}x} + \frac{-bx}{(\sqrt{a - bx} + 4)} + \frac{-16}{(\sqrt{a-bx} +4)^{2}}$
texaspb
is this expansion correct?
no
i dont think so just by looking at it you can add all those and get a common base from those partial fractions
Preetham
uuh I don't get it
why is there 2 prices of apple pies
no clue:(
@viscid thistle hmm I think i understand now
so
f(p) has linear relationship therefore it is in the form ax + b
a and b are constants and x is the amount of pies bought
if you substitute those values given you get a system of equations
3000 = 500*a + b
2300 = 325* a + b
and then you solve for a and b
ohhhh
in this case a will be the price of each unit of pie
and b will be a constant that means something like "the price of starting the production of pies"
omg thank u sm u are a lifesaver
you are welcome!
i cannot figure out sum and difference formulas for the life of me
and manipulating sin/cos waves, will post an example soon
If someone knows a trick to look at them differently, but i cannot figure out the proper way to break down cos(x) into a sum and difference formula to solve it
Anyone how to find all solutions for the following equation: sin(-3x)=0.5? Only found one solution so far which is: (2*pi/3)n + 7pi/18
sin(X) = 0.5 only for X = 30 ° (pi/6) or X = 150° (5pi/6)
however that is true only for the first lap in the unit circle so you need to add 2pi*n to your solutions (where n is a natural number that represents the numbers of laps around the unit circle)
I did it but there seems to be a second solution taking n into account in the soln as well which I have not been able to find out how to write from the eq above
yeah so
for examploe : sin(pi/6) = 0.5
so : -3x = pi/6 --> x = -pi/18
but thats only for the first lap around the circle
so your answer in this case should be
x = -pi/18 + 2*n*pi (n is natural)
the other solution is when -3x = 5pi/6
that also contains the + 2 n pi
ooh ok
le haut c trop compliqué pour comprendre
mais en bas je crois que c 48 et après 192
it should be -3x = pi/6 + (2pi)n
cos(165)=cos(120+45)
For the first one, you'll notice that the numerator is a factor of the denominator
so if you can factorise the denominator, the numerator should cancel and you might be left with something cleaner
something similar is true for each of the rest.
someone pls help it’s related rates
Can u send the diagram if they gave it in the question ?
they didnt attach a diagram unfortunately
Oh ok
How would I solve the top equation, can someone please help with this I’m stuck with what identities I need to use
<@&286206848099549185>
,rotate
sin(x+y)/cos(x)sin(y)=1+cos(x)tan(y)?
.
Question on Set Theory and describing Rational Numbers (it’s in my pre calc text, apologies if this should be asked elsewhere).
So thr first line is incorrect and my second line is correct?
yes
That is disconcerting. The first one is how it’s written in my text. The second is what made more sense to me.
So now I wonder how much else is wrong in thr textbook
Yes
I’m not sure the identities I need to use @fast oxide
if you put this imaginary number in polar form you can do it easily
I am not sure on how to solve this question. can anyone help me?
f(α+β)=tan(α+β)
Using the figures, tanα = -1/x and tanβ = -3y
Then you can simplify to get the final answer
Oh wait
tanα = 1/sqrt(3) and tanβ = -2sqrt(2) (since x=-sqrt(3) and y=2sqrt(2)/3)
Thx Alot i love you. What math does a mf
Help. I'm stuck converting the trig function into exact form.
I've derived the function to -cos(5pi/6)
I have checked the marking guides and it is equal to root/2
What's the process for getting from the function to the esact value/ratio?
So I finally figured that bit out but now I have to put it into the gradient formula y-y1=m(x-x1)
I did similar except instead of using pi/6, I made it 1/2 exact ratio since sin pi/6 exact ratio is 1/2, or am I not supposed to do that and leave it as pi/6 because you can't convert it as it is a point and not part of the sin function?
(Also I'm most farmiliar with slope intercept form over general form so that makes working backwards that little bit harder)
Also I see questions happening in both places. In future is it better to just go straight to a "help" room?
<@&286206848099549185>
wrong channel
Hi
So the question is Given f(x^2)=f(x)+x^2 find f'(1)
I don't want the answer
but a hint
I'm stuck
Take the derivative of both sides.
Dont if you put x=1 you get 1=0?
?
It's f'(1) not f(1).
In f(x^2)=f(x)+x^2
wdym?
If you put x=1 in that you get f(1)=f(1)+1

