#precalculus
1 messages · Page 20 of 1
you can rewrite this as $2(\frac{ln(x)}{ln(2)})=x$
prime
ah, this is an intermediate step
Can you explain how you got this please
dude this is the precalculus channel
you want to go to the calc channel
I can help you in dms if you need
I got a question. I had to determine if a equation would be even and odd on a graph by using f(-x) and -f(x) on a quiz. I got the answers right; however, she subtracted 1 point off of each question because when showing my work I didn't include f(-x) and -f(x) in my problem. So for example I wrote 2x+4 instead of f(-x) = 2x+4. She never told the class this. The answer she wanted was either odd or even so I just did the work and didn't bother labeling because I only needed to circle odd, even, or neither. But those points she subtracted off left me with a 19/22 on a test that I would have gotten a 100% on. Is this fair? Should I ask her about it or is it my fault?
To be honest, it seems more like miscommunication than a fault on your part, so you could talk about it to your teacher. Tell her you understood the concept and correctly identified whether the equation was odd or even, even though you didn't write out f (-x) and -f (x), and that the main understanding was the mathematical concept, and the labeling requirement wasn't explicitly communicated. 
okay thanks 👍
my friends who got a 100% on the quiz said that they just put that there out of habit and also didn't know you had to as well. And they all said I should talk to her about it.
What are some great books that teach precalculus through real world applications like physics or engineering?
everyone always sees the precalc channel and is like yep, precalc has integrals
its cause they take the 'calc' in precalc too far
then arent we allowed to ask help for integrals etc things here?
not in this channel
you should ask in #calculus
are you learning this stuff in high school, and if so, are you perhaps doing a higher math class?
calculus is a part of high school wdym
derivatives, limits belongs to this channel right?, arent they
PRE calculus, thus stuff you learn BEFORE taking calculus
In the US, whose traditions inform the channel organization, calculus is commonly taught in the first year of university. Therefore the #calculus channel is located in the "early university" category. That doesn't mean one has to actually BE in university to use it. The categories are just a practical arrangement to avoid having all of the channels lumped together in one long list.
oh ok, thanks 👍🏼
wait calc is for university?
????????
i never knew that
interesting
Depends on which country/system you're in.
this
calc can be taught at pretty much any level depending on the country and education system
typically, unless youre taking math as a course, most university STEM courses etc will require you to do math as a module which includes calculus
I'm led to believe it is not all that uncommon in the US to learn calculus in high school. They just tend to think of it as "particularly bright/interested students get to learn some university topics early".
Conversely, it is not uncommon to see basic calculus taught at European universities -- just billed as "remedial high-school mathematics for STEM students who followed a low-math track in high school".
So the actual differences on the ground might not be as profound as the overall generalizations suggest.
im a hong konger taking IB. Usually we math nerds get taught it early in 10th or 11th, but we also have it for 9th grade as a super-extension task. I am a freshman, but because of 🤓 , i've already learnt the equivalent of roughly 25-30% of calc 1
including me, there are 3 people in my maths class (higher level, rigour based, we call it "Pure maths") who know calc
i thought it was a high schooler subject
hi whats the log in base 1 of 1?
"Log in base 1" does't make sense.
can anybody explain the rational root theorem and how syntetic/long divison for polynomials work
like why does the algorithm work
Can anyone help me to solve this?
Eq. 41
dawg is this multi variable calculus
nah precalculus 💯
watch youtube videos about the topic; just search up on youtube about the rational root theorem and long division...and you will understand my friend
Is there any limit
[ \lim_{x \to k} f,(x) = 0 :, \quad \lim_{x \to k} g,(x) = 0 :, ]
such that
[ \lim_{x \to k} {f,(x)}^{g,(x)} \neq 1]
ταυταυ
I found one btw
ive been finding videos on its application
i havent been able to find any videos on the why though
ill keep searching
anyone know why ap precalc is a thing now
for these problems do you reflect first, translate left/right, then up/down?
for example, 37 would be reflect over x axis, then shift 1 right, and up 2
quick question is ratio of cotθ the same thing as finding the exact value?
im sorry to bother, but can you help me with this question? given sinθ = 4/5, secθ<0, determined the ratio of cotθ
and how can you rewrite tangent then?
idk what youre trying to ask, i just know that cot is inverse of tan
There’s a special way you can rewrite tangent in terms of sine and cosine
and since cotangent is the reciprocal you can flip that
I tried the question myself, is the answer cot = 3/4?
draw out your triangle it makes things easier
I understand that
yes
now why do you wanna confuse the lad
bruh
ok
Wait so how did you solve it?
Can you put your work in here?
I could
will you though
yeah that’s a valid way to do it
am I complicating myself?
not that ur way is complicated but there's an easier way
Is there an easier way ?
but the way we were thinking is by doing cot (theta) is cos/sin
then you sub in the value for sine and the pythagorean identity version of cosine
and plug in and simplify
your way is completely valid and probably less abstract anyways
If one of you guys can write it down for me, that’d be great
u don't even have to use that you can just use sohcahtoa
you still have to solve for c that way, it’s basically the same
u can understand the sin bit through sohcahtoa
secθ<0
can someone explain this to me?
i view it as when cosine is + or is it -?
The inverse
The negative
Sec=- ?
1/cos
This sign means “<“ greater then right?
So then cosine is greater then 0?
its the same question from above
i just want to make sure I understand it
Cause i guess on that sec part
all i want to know is
when sec < 0 is equal to +
when sec > 0 is equal to -
?
when putting it inside the quadrant
ok thanks
I havent learn that yet, but it’d come in handy soon. I appreciate the help
While finding max of function using derivative can we directly assume the point of Max the point we get after equating first derivative to 0 without checking the sign of second derivative ?
no
Consider x^2
Then he just calculated the 3² so it became 9x² ?
Oh okay thanks !
Well, I believe the correct way of saying it would be "the negative reciprocal"
its the quantity squared, so yeah
hi calculus here 😎
damn
C A L C L U S
calclus is best type of calculus
fr
ikr?
Yo calculus can you tell your friend statistics that nobody likes him and he should just leave this plane of existence

Will do
Lmfao
predicting
bravo to the people that have actually went into that field of research
Quick question: How do I verify this identity?
sinx/cosx (I just simplified if from tanx)
do something about left hand side
Hold on am I bugging or does the left simplify to -cosx
If u plug in pythagorean identity for 1
I did
The original identity was:
This is the original identity.
what is your question?
why is there a second identity and which one are you asking about
How did u go from this to the first pic
Can u send solution I am curious
Lol
you're welcome
Do I cancel out the 9/4 sec^2theta. Or do I simplify the radicand first?
there's nothing to cancel
oh lord
-1 + sin(x)^2 = -(1 - sin(x)^2) = -cos(x)^2
-cos(x)^2/cos(x) = -cos(x)
you dropped the - sign from the previous line
which came from chain rule/derivative of
35 - 5sec(x)
also with the presence of differentiation, it's calc not pre-calc
please use the correct topic or claim your own channel
you're missing a U 🤨
No way 🤯
Thank you ❤️
You can’t cancel the $\frac{9}{4}\sec^{2}(\theta)$, you can rationalise the denominator though, but that would make it very chunky. It depends on what is expected of you to do, but I probably wouldn’t change anything about this.
TheLord26
Is there a section for calculus bc I am taking AP calculus ab
uts probably grouped together
How you taking geometry and calc

ryan has been exposed
just #calculus 😭
dont tag
when its csc(5pi/2) can i look at it as sin(5pi/2) ?
Both csc(5pi/2) and sin(5pi/2) happen to be 1, so they are the same -- but only for that mostly accidental reason.
how to i go from exact values to radians
example -> cos(1/2)
what would that be in radian form?
Huh. Do you mean the cosine of half a degree, and you want to write that half a degree in radian form?
i figure it out,
cos (1/2) = pi/3, 5pi/3
thats all i wanted to know
You mean to say the solutions to cos (x) = 1/2 are x = pi/3, 5pi/3.
trigonometry is fun !
At any given point or like finding secant lines
Given 2 points
If it's linear like a line you can just do rise over run
Difference in y/difference in x
What about calculus
In your highschool probably
probably youtube or something
you might wanna work on algebra and trig some more before you start studying calculus though
can't really do it well without the foundational stuff
literally tbh
ik trignometry and algebra
trignometry basic lvl
lol
have you done like. csc sec and cot stuff
I'm in 11th grade
W
when it comes to algebra how do you feel to that end
personally i likee algebra more than anything in maths
okay cool
if I were you instead of looking at calculus i'd become more familiar with trigonometry
probably look at trigonometric equations, polar coordinates, and complex numbers just to get again a good base
they usually come in handy later
and then when it comes to algebra if you haven't done this stuff already I recommend getting very very comfortable with conic sections and piecewise functions along with inequalities
all those are really prep for calculus
if you want to dive straight in though, I would check out 3blue1brown's video on the subject and maybe see if you could do some on khan academy as they have fairly in-depth calculus resources
yeah of course
which country are u ?
from the US
oh ok
calc on top, linear algebra scares me
linear algebra in uni is very fun you'll see 
i do uni-level linear algebra, its definitely not fun.
linear algebra truly is iconic tbh
i love it
uhh js go on yt or start with the stewarts textbook
if u wanna learn p basic calc go up till chp ig 6?
after that its haevy integratation based
also make sure u can do basic math rly well cuz like it is very heavy algebra based when ur solving the stuff
imo u dont rly need precalc for calc
you dont need it necessarily but it does have its usefullness later down the line
Guys,would you mind some of you can help about that
Solved in #prealg-and-algebra
thanks for the heads up btw
2 + 2 is 4 minus 1 is 3
can someone help with composite functions
Those are not composite functions
Can you show what you have so far?
They're plainly composed of f and g (and the addition and subtraction operations).
Anyone can help me with this
-
( \lim _{n \rightarrow \infty}\left(\frac{2 n^{-2}(n !)^{3}}{3(n-1) ! \cdot(n+1) ! \cdot(n-2) !}\right) = \lim _{n \rightarrow \infty}\left(\frac{2 n^{3}}{3(n+1)(n-2)}\right) = 0 )
-
( \lim _{n \rightarrow \infty}\left[2 n^{2}\left(\sqrt[3]{2 n^{3}-1}-\sqrt[2]{2 n^{3}+1}\right)\right] = \lim _{n \rightarrow \infty}\left[2 n^{2}\left((2n^3)^{1/3}-(2n^3)^{1/2}\right)\right] = -\infty )
-
( \lim _{n \rightarrow \infty}\left(\sqrt{n^{2}+5 n+3}+\sqrt{4 n^{2}+2 n-1}-3 n\right) = \lim _{n \rightarrow \infty}\left(n\sqrt{1+\frac{5}{n}+\frac{3}{n^2}}+2n\sqrt{1+\frac{1}{2n}-\frac{1}{4n^2}}-3 n\right) = n )
-
( \lim _{n \rightarrow \infty} \frac{\sqrt{n+2}-\sqrt{n-1}}{\sqrt{9 n^{2}+2}-3 n} = \lim _{n \rightarrow \infty} \frac{1}{3\sqrt{n}} = 0 )
-
( \lim _{n \rightarrow \infty}\left(\frac{1+3+\ldots+(2 n-1)}{n+3}-n\right) = \lim _{n \rightarrow \infty}\left(\frac{n^2}{n+3}-n\right) = \lim _{n \rightarrow \infty}\left(\frac{n(n-3)}{n+3}\right) = \infty )
-
( \lim _{n \rightarrow \infty} \frac{1+\frac{1}{2}+\frac{1}{3^{2}}+\ldots+\frac{1}{3^{n-1}}}{1+\frac{1}{5}+\frac{1}{5^{2}}+\ldots+\frac{1}{5^{n-1}}} = \frac{\frac{3}{2}}{\frac{5}{4}} = \frac{6}{5} )
-
( \lim _{n \rightarrow \infty} \frac{\sqrt{n}}{\sqrt{n+\sqrt{n+\sqrt{n}}}} = \lim _{n \rightarrow \infty} \frac{1}{\sqrt{1+\frac{1}{\sqrt{n}}}} = 1 )
-
( \lim _{n \rightarrow \infty} \frac{n \cdot \sin n}{n^{2}+1} = 0 )
-
( \lim _{n \rightarrow \infty}\left(\frac{\mathbf{1}}{\mathbf{1} \cdot 3}+\frac{\mathbf{1}}{2 \cdot 4}+\ldots+\frac{\mathbf{1}}{n \cdot(n+2)}\right) = \frac{1}{2} )
-
( \lim _{n \rightarrow \infty}\left[\left(1-\frac{1}{4}\right)\left(1-\frac{1}{9}\right) \ldots\left(1-\frac{1}{(n+1)^{2}}\right)\right] = \frac{2}{3} )
Zeuro
@heady elbow check
Holy
Is it asking for the rate per hour?
Folks in this graph problems ,we suppose to use vertical and horizontal asymptote or Someone have a idea ?
103?
so 340 = 170(1+x)^5 where x is your percent
Yes this one
basically you're able to tell graphs based on their shape and where the holes are
the holes being where things on the top and bottom camcel
for this equation can you cube a negative number?
Why wouldn't you be able to?
so you can cube a negative number?
yeah?
so when i cube it does it become -1? like how you would square root 1?
I think I see what you're asking. Yeah, it's possible to do that. All odd roots are able to be done on positive or negative numbers. It's only even roots that are bound to positive numbers
when i cube it, it becomes 2cosx=-1?
Umm, what is the "it" you're cubing to get that?
the equation up there
that^
Cubing (each side of) that gives 512cos^9(theta) = -1.
im isolating the equation to find cosine
You isolate by doing the opposite operation. So dividing by 8, and cube rooting
Which is why I mentioned the odd and even root thing. Thankfully since it is an odd root, you can root a negative
@exotic barn ok so i noticed that when you have a zero in the denominator thats not in the numerator of a rational function thats a vertical asymptote and if theres a shared zero in the numerator and denominator then its a hole but is it possible to have a jump
yeah, why did you ping me hahaha, you said the same thing previously to that girl of yours lol
on god shes my girl 🥶 but i pinged you because you r smart
haha thanks
i cant think of when a rational function would have a jump
im getting the vibes
that it has something to do
with limits
and rates of change
but vibes only take you so far
Rational functions don't jump, but they can have vertical asymptotes even where the numerator is 0 -- consider for example x/x².
(Silly example, but the instances of this are generally silly in the same way).
mannnn
why cant they jump though
oh wait
rational functions are just polynomials
nevermind
i mean any function with a numerator and denominator part
Hmm, I don't have an elementary argument for that ready.
nah ur good i kinda get why polynomials dont jump but if u got an explanation at any point pls share
Well, in that case |x| / x does jump.
how would you identify jumps in a graph
other than by just looking at it
I'm not sure how to do anything with a graph that's not looking at it ...
moreover how would you describe them like would you describe them by their left and right point and which point is defined
noo i mean like
actually
idk what i mean
If f(x) = x^3-5x^2-4x
and g(x) = 2f(x) + q
Find all values of q if g(x) has exactly one x-intercept
hello guys, u discuss here about the basics of calculus?
closed interval
So it is the union of -infinite to -3 and 0 to infinite?
are you talking about the red one or the blue one?
The red one
oh okay so yea it is the union of -infinite to -3(not included) and 0(included) to + infinite
and the x in blue is thier final result, that is thier intersection
This is another part I don't understand. Every negative x ≤ -3 would result on the equation "x²+3x" being ≥ 0
Why it shortened it to [0, 3]?
you mean $\cup$ and $\cap$ right
RottenGold
$\cup$ is called the "union" of 2 sets, it combines 2 set. $\cap$ is the "intersection" of 2 sets, it finds the overlapping elements of 2 sets
RottenGold
Oh, I understand now
I missread the question
lmao that happens
Because of |x| ≤ 3
A thing I hate about learning maths is sometimes having to spend more than half an hour on a single page tl understand it, but it is fun
you can take the cubic root out of the equation, it would be 2cosx=-1 then cosx=-1/2 and finally arccosx=-1/2 then x= 120 or 2pi/3
hello everyone i have a question , im 10 grade right now and i want to start learning precalc and after calculus by my self but i dont know where can i start can any one tell me the roadmap or something like that
I recommend using An igsce addmath book
That's where I studied all my base of calculus from
alright thanks let me search about it
is this not a dirichlet function ?
I'm studying my precalc with the openstax book
Ill tell you chapters that are normally hard is binomial and vectors
The calculus part such as derivitives and intergrals are easy
Trignometry is also a hard chapter
so which one i have to start first and also i want to take ap calc ab at next year
The book starts of with functions
I sent you in dms
The book I used
Just curious what I should be finding with a question like this. I understand the end goal, and generally what it is I'm supposed to do, but I don't really know how to start it
I'm just self-learning, and I'm not in an official course, so I'm just a bit confused. My school back then never really covered trig with functions, so I'm inexperienced with this type of situation
I don't need the answer, just want to know what processes I should be applying to that question
Does anyone know how to simplify this
idk think it can be simplified any further but the only thing i can make sense of is multiplying both side by 1-sin theta
@strong epoch
I tried that
Got that bottom would become cos^2x
Then wouldn’t it be -cossin/cos
I thought it was -sinx but it was marked wrong
how are you getting
-cos(x)sin(x)/cos(x)
Doesnt cos/cos^2 simplify to 1/cos
cos/cos^2 does simplify to 1/cos,
but you don't just have cos/cos^2
I know that’s where the -cosxsinx comes from
Can I just simplify it like that?
no
fractions get simplified from cancellation of a common factor
and not erasure of expressions that happen to appear
here you'd want to factorise the numerator
or not have expanded in the first place
So -cos(sin)
no
no
What is it cos( 1-sin)
Cos( 1-sin)/cos^2x
$\frac{\cos(x)(1-\sin(x))}{\cos^2(x)}$
ℝαμΩℕωⅤ
now that it's clear that cos(x) is a factor of both the numerator and denominator, you can cancel
not really sure how to finish this question
this is my working out, but i dont know how to eliminate the value for a
Just use the formula sin-1 x + sin-1 y
Then we know that sin-1x = pi/2-cos-1x
Then just euqate the angles for x
alternatively, take the sin/cosine of both sides
the identities can be found from a right triangle
anyone have any tips for gauss elimination
google fang cheng
its gaussian eliminqtion without fractions
Fractions got you down? We illustrate an ancient Chinese method of solving multilinear systems that avoids fractions until the end of the problem.
For more math, subscribe to my channel: https://www.youtube.com/channel/UC1KV5WfubHTV6E7sVCnTidw
and then convert to gauss-jordan
Getting a matrix into reduced row echelon form.
this is seperate from gaussian elimination
well its a type of gaussian elimination j without fractions
it's standard gaus
no bc this way avoids fractions
How do i find this point? Where the arrow is pointing
im looking for the phase shift of the function
solve f(x) = 0
I urgently need someone who knows Calculus
Google is pretty good at it
if you know the function of the graph, you can find the phase shift. in the form $a\cdot\sin(b(x+c))+d$, a is amplitude, b is the period, \emph{c} is phase shift and d is verticle shift. in the form $a\cdot\sin(bx+c)+d$, the phase shift is found with $\frac{c}{b}$
TheLord26
it's 2 cm + 4 * (4 + 1) cm
22cm
im suppose to write an equation for the graph, ik the amplitude, and vertical displacement, im missing phase shift and period
Just approximate then, you aren’t given any exact values.
the only values im given is the numbers that are marked on the graph
If that is all the information you have got, then this is the answer: $y=6\cos\left(\frac{2\pi}{3}\left(x+\frac{\pi}{24}\right)\right)-2$.
TheLord26
What with?
What do I need to know before I venture into calculus?
is there an equation i can use to find the phase shift or period?
Count.
Basically what I did was counted how big each of those units are, which was pi/24, from there it was pretty easy.
trig
and a good amount of algebra
yeahh
i gotta step up my algebra game more ngl
im not in college still but next semester, i'll be taking up basic calculus
The most important things that you should revise is logarithms, exponents, fractions. (At least that’s what I think)
Also if you’ve done complex numbers before those are pretty annoying to divide.
Help
I don’t understand why it’s not the thing I circled on the top (not the answer)
Isn’t converting it to a different time rate make it like that?
Because the value increase one per month, it stands to reason that it will increase 12 times per year. And because t is time in years, you have to multiply the value by 12.
What you have done is multiplied 12 (the number of times the price increase per year) by t/12, which cancel out, thus leaving you with just t.
And because the price doesn’t increase only once per year this is wrong.
Omg Ty so much
Okay I can do most algebra
Trig needs more work
For a bit of background context, I'm technically not in school right now, and haven't been for a little while, so while I have taken pre-calculus before, I'm a bit rusty. I understand what the question is asking me to do, but I'm not sure how I'm supposed to go about doing it. Can anyone tell me what formulas or rules I'm supposed to use on this one? Not necessarily asking for the answer (you can provide if you want, I don't mind), I'm just curious about the process itself
Help, what are the rules for integrals
,tex .int rules
Akira (fumo)
i was doing random stuff with exponents when i found smth weird
so i have x^x right, and it's defined on [0;+infinity[ since apparently 0^0 is 1
but as far as i know you can write x^x as exp(xln(x)) which cannot be defined on 0
my question is where did i go wrong, is there something i didn't do correctly when i rewrote x^x ?
because 0^0 is not 1, it's undefined
What about this? I've been having trouble with this, lol
ah, i've seen from some sources that it's 1
thanks
draw the picture
Pro tip for math: don’t mess with 0.
i guess i'm just gonna
Guys, what algebra and trigonometry do i need specifically to be able to understand calculus?
👍
all of it
a whole lot of algebra
idk about trigonometry
but probably all of it too
Lol I thought that as well when I first read the message.
all of the algebra and trigonometry? wdym by that? Everything that has been published? 😄
Google “what does a pre calculus course have”
everything that's part of the school algebra and trig course
Ahh yes, my favourite precalculus course, Algebra A.
Once again, calculus is 90% algebra
I generally know what it looks like, the problem is I'm not sure about the equations. I don't think I'm supposed to find the answer with a graphical solution
it's not like the exercise explicitly forbids you to use valid mathematical tools?
Of course, but I'm pretty sure there's an algebraic solution, no?
once you draw the picture the equations will be obvious
I mean if you can't even visualize the problem in your head and what it's asking, then it's not clear how you would come up with algebraic solution
taylor series
I wouldn't have a problem with the question if it was asking for just a function period. But it's asking about the function of the slope. I'm not sure how to create the final answer based off of just that variable
try to figure out the slope of the line joining P with the origin first
And is a graph required to do that? Like I can't do it any other way?
depends on how well you understand what the problem is asking
you already given the information what the coordinates of P are technically
in the problem statement
The problem is, I don't know how to find the coordinates. I was trying to find them earlier, but I must've been doing it wrong. That's why my original question was asking what equations or rules I have to use to find it. I've done a problem like this before, but it was years ago, and I'm just rusty
suppose P has coordinates (p_1, p_2) and you're given that P lies on the graph of f(x) = sqrt(x)
what can you say about coordinates of P now?
and it being in the first quadrant
Try graphing stuff on Desmos.
Am I just misunderstanding the question?
What do you think the question is asking?
I thought it was asking what point on the unit circle had the same point as a point on the line of sqrt(x). I know, I know, the question didn't explicitly mention it, but I assumed because of the word "quadrant", I think that threw me off
Am I only worrying about the sqrt(x)?
You understanding of the question is incorrect. A quadrant means the positive/negative values of x and y (google Cartesian plane quadrant). And you are trying to find the slope of a point passing through y = sqrt(x).
Yes
Okay, thanks, that simplifies what rubbish I was trying to assume it meant, lol
That should be good, I think I know what to do now
The first quadrant is whenever the x and y values of a point are both positive (in this case every point you are working with should lie in the quadrant).
Right. I just never heard that term outside of trig when I used to go to high school, so I always treated it as a "trig term"
Understandable.
If you need any more help I’ll probably be around
Aighty thanks. I should be fine for now. I'm actually not looking at a pre-calculus textbook, I'm doing calc, but I'm in the first chapter which consists of pre-calc stuff, so I'll probably stick around here for now
Actually one more thing. What is meant by a "natural domain"? I don't think that term ever showed up where I went to school. I know about domain, but I don't know what a natural domain is
Well the domain is what you set it as, and the natural domain is what is defined by the essence of the function. Take f(x)=sqrt(x) for example. It’s domain is everything in the first quadrant, not because you defined it as that, but because that’s just how the function is.
So depending on the question, they can mean exactly the same thing, if there wasn't a domain restriction, since natural domain has no restrictions except what the function itself has. Gotcha
I figured that's what it was, but I was confused, lol
Don’t worry, you might not be used to how some text books say or do things.
My teacher absolutely hates a certain textbook because of how it says stuff.
Yeahh, I think my schools always had their own sources, so I'm not familiar with math textbooks in general
I got used to it cuz I used 3 different text books.
Dang, nice. Right now I'm using Thomas' Calculus book. I know this covers like 3 courses in 1 book, but it should still be helpful anyway
Nice, might check it out.
Well, I’ve got some time to kill later today. I’ll get a start on it so I don’t feel lazy.
can someone help me find the phase shift of this cosine graph
can any one solve this
There is none or it depends really
$\int \rm{x^n dx}= \rm{nx^{n-1}}$
ഴajat
and then put the limits
ok thanks
yes, youre right! there is none.
No, that’s the derivative instead
Yea that's just wrong
$\text{power rule}\ \int x^n dx = \frac{1}{n}x^{n+1} + C\ \text{and then use fundamental theorem of calculus} \ \int_{a}^{b} f(x)dx = F(b) - F(a) \ \text{where b > a and F(x) is the antiderivative of f(x)}$
someone1010
are the vertical asymptotes 4 and -3
it says it’s only 4 on mathway
but i think i’m supposed to plug in -3 and 4 on the number to find the limits
That is correct
If the binomial cancels in numerator and denominator you get a point discontinuity rather than a vertical asymptote
Ex: (x+1)x/(x+1)
,w graph (x+1)x/(x+1)
notice that there is no asymptote
Well, a/a = 1
yeah
It doesn't go to inf bc it cancels
Not sure how to rigorously prove, but 4 doesn't cancels so it makes an asymptote, though that's not a satisfying explaination
ok
so in other words is this right too
Probably
Is this the notation of a primitive function ?
it's second derivative
Thanks.
oh yea lmao didnt noticed that lmaooo
Total number of calls:
We know that the average number of calls per hour is 30. Therefore, the total number of calls in 150 hours follows a Poisson distribution with parameter (\lambda = 30 \times 150).
Number of men in calls:
Since 60% of the calls are made by men, we can consider the number of men in 150 calls as a binomial random variable with parameters (n = 150) and (p = 0.6).
Waiting time for reward:
The time between calls follows an exponential distribution with parameter (\lambda = 1/30) (since there are on average 30 calls per hour). So, the total time elapsed before the 100th call arrives is a sum of 100 exponential random variables.
For calculate these probabilities, we use the approximate Poisson distribution for the sum of independent random variables. The Poisson distribution can be used when the number of events is large, and the probability of success for each event is small.
In detail, you can use the Poisson distribution approximation for a binomial random variable when the number of trials (n) is large and the probability of success (p) is small.
For the first point, you want to find the probability of having at most 75 men in 150 calls, we can use the binomial distribution.
For the second point, we want to find the probability that the waiting time for the hundredth call is at least 3 hours, we can use the Poisson distribution.
@viscid thistle
☆⃞゙۪ ᪤hiִgh࣪nᧉ͟s̲s: 🫶🏻 𝖨𝘇𝗓𝕪 ܲ 𖧪
[ P(X \leq k) = \sum_{i=0}^{k} \binom{n}{i} p^i (1-p)^{n-i} ]
- ( n = 150 ) (total number of calls)
- ( p = 0.6 ) (probability of a call being made by a man)
- ( k = 75 ) (maximum number of men)
Calculate is
[ P(X \leq 75) = \sum_{i=0}^{75} \binom{150}{i} (0.6)^i (0.4)^{150-i} ]
For the second point, you use the Poisson distribution to calculate the probability that the waiting time for the hundredth call is at least 3 hours. The formula is:
[ P(T \geq 3) = 1 - P(T < 3) ] - ( \lambda = 1/30 ) (rate of calls per hour)
- ( T ) is the sum of 100 exponential random variables with parameter ( \lambda )
Calculate is
[ P(T < 3) = \sum_{i=0}^{299} \frac{(1/30)^i e^{-1/30}}{i!} ]
In the end:
[ P(T \geq 3) = 1 - P(T < 3) ]
☆⃞゙۪ ᪤hiִgh࣪nᧉ͟s̲s: 🫶🏻 𝖨𝘇𝗓𝕪 ܲ 𖧪
thank you very much, will look into it
Np
can you also explain the second one?
Sure
You can use those methods:
• Method of Moments:
The method of moments uses sample moments to estimate the parameters of a distribution. In the case of an exponential distribution like this one, the first sample moment is equal to the expected value of the distribution. So, we need to equate the first sample moment to the first theoretical moment. For the exponential distribution, the first theoretical moment is ( \frac{1}{a} ).
Calculate the first sample moment (( \bar{X} )) and solve for ( a ):
[ \bar{X} = \frac{1}{a} ]
[ a = \frac{1}{\bar{X}} ]
• Maximum Likelihood Method (ML):
The maximum likelihood method finds the value of the parameter that maximizes the likelihood function. For the exponential distribution, the likelihood function is given by:
[ L(a) = \prod_{i=1}^{n} a^2x_i e^{-ax_i} ]
It's often more convenient to work with the logarithm of the likelihood function (log-likelihood):
[ \ln L(a) = \sum_{i=1}^{n} [2\ln(a) + \ln(x_i) - ax_i] ]
Take the derivative with respect to ( a ) and set it equal to zero to find the value that maximizes the log-likelihood.
☆⃞゙۪ ᪤hiִgh࣪nᧉ͟s̲s: 🫶🏻 𝖨𝘇𝗓𝕪 ܲ 𖧪
thank you very much
How's this precalc
thats what im fuckin sayin
technically 1+1=2, is pre calc
is it before calculus: yes
<@&286206848099549185>
matrices- my enemy-
<@&286206848099549185>
what are you plugging into your calculator? and what is the problem, is it the negative? perhaps one of your assumptions is wrong.
can anybody help me with understanding the basics of transformations, translations, and dilations of a linear function?
Use desmos
When 2X replaces X, less of a value is needed to replace Y value
Hence graph is factor of 1/2 along X axis
what are you using to transform the line? are you using matrices or just calculus?
what are the cosh and sinh functions for, i know they exist but i’ve never seen them be used
It doesnt workk
It shows different answer
x^2/(3sqrt(2)/2)^2 + (y + 21/5)^2/(3sqrt(2))^2 = 1
,help
A brief description and guide on how to use me was sent to your DMs!
Please use ,list to see a list of all my commands, and ,help cmd to get detailed help on a command!
x^2/9+(y+4.2)^2/36=0.5
how
brains not braining
n=19
n=23,27,31
ok done
idk why my butt is itching and i see the form 2^(3n)-3^n being divisible by 5
sorry i am bit drunk today
i scratched my butt and for n=3+2k for k>=2 and k=0 agrees
Is anyone good at logarithms and exponentials?
Don’t ask a question like that. Just post the question you are resale trying to ask. Otherwise you will probably not get a response, and even if you do get a response you will have to follow up with another response to ask the question you initially wanted answered.
My apologies I have it posted I've just been patiently waiting
Well what’s the question?
It's in the channel help 37
Can you link the channel?
can anybody help me
just post the question bro
i swear, people just be asking for help instead of just asking the question.
bro i spent 20 minutes just to get that too😭
no im supposed to be by this point tho
They are pretty easy to learn, and they are basically the holy grail of trigonometry.
arctan(1/sqrt(3))=60 degrees.
x+135=60
x=60-135
x=-75
are there any more answers or is it just -75
if it didnt ask for anymore solutions than you dont need any more.
its between 0 and 360 degrees so there can be multiple answers
Not that I've heard of before.
Figure it out if you think there are more answers.
They have exact values for the side lengths of triangles with interiors 45-45-90 and 30-60-90
i said exact value triangles.
huh, ive never heard of them being refered to as anything different, neither in text books, youtube videos or from teachers.
they arent really special, other than the fact that they have some of the most commonly used angles in them, and easy to represent side lengths.
Well all triangles have constant proportional sides.
take a right angle triangle with interior angles 15 and 75.
Set one of the side lengths equal to 1.
Solve for the remaining sides.
bam, proportional triangle.
What makes it proportional then?
yes, the triangle i have just created has all 3 sides being constants.
you do know what a constant is, right?
I made them the constant, therefor anything that shares the same angles will be proportional to the triangle i made.
They just have commonly used angles.
tanx/secx simplified is sin x right
Yes
I have a question: what are all the rules for logarithms and exponentials?
This is correct.
Thank you, and which one would be the one you mentioned before? It was like a^log_a(x)=x
those arent all the log laws, but you should be able to do all questions using them.
Oh
here are a few more
Thank you
M and N must be positive factorial
it says that in the second image, the one you replied to.
I’m making a joke with ! And factorial
oh
im too tired to realise
dammit
i should have picked up on it, i love those kinds of jokes.
It’s just a trig function. Tan(31)=450/x
It means you’ve messed up.
Try dividing the entire equation by a constant (hint:||3||)
Which equation?
3x+9z. It’s the only one I can see, so there might be an easier way to go around solving it.
I'm trying to find x,y,z
At this stage I would find out what x was but it becomes zero?
The calculator says I get
z=z
x=0-3z
y=6+z
But idk how
I don’t have a piece of paper on me rn, but start by doing equation 2-3(equation 3)
You're saying 2-3 then plug that into equation 3?
That gets me 0 = 0 I've tried
Solve for y and z first.
Do you know how to calculate where two lines meet?
Yes, using elimination I got 0 = 0
Huh
Check back in your working out, are you doing -(eq3), remember into distribute the -1 onto all terms?
Because if you focus on eq2 and eq3 by them selves, it is the same process for finding the values of y and z.
So I do
-(y-z)=6?
I get -y+z=-6
What i do with this
Multiply it by 3 giving you -3y+3z=-18
Then add the second and third equations together
That make zero?
No it doesn’t.
Wait
I’m getting confused with something else
Lemme just go do this on paper rq
Okay
Appreciate it
Considering one of the equations I got was x+3z=0, and the calculator says x is supposed to be 0-3z, it looks to me I'm supposed to get x by itself? But why
And how does z=z
Does this question come from a textbook?
Nope
So you created it?
No
Where’s this question from then?
It's a practice question generated from a professor
Uhhh
But the calculator provides answer
What does calculator give you?
X = 0-3z
Y = 6 +z
Z = z
I was saying here
Wait
Ok
You’ve got 5 equations?
I made the next 4 and 5
Huh
3 were the question part
Are you trying to find z?
I'm trying to find x,y, and z
Yeah but what is the reason we write the answers like that
When I say “find z”, I mean like, it’s value (4, 19, 3.14, ect)
And if the calculator just says z=z, that means it’s impossible.
I see so since I got 0 = 0 it's impossible to find z and we have to write x and y in a different way
?
I think it's like you have to write x and y in relation to z
Put it this way, it’s like trying to the intersection point of two lines, but the they are the same line. So there is no single intersection point.
Yeah
That means the value of z does not exist.
What abt x and y
Well considering how we can’t solve for x or y without using z, it means that they are also impossible to find.
Oh
This happens because eq2 and eq3 are just the same equation.
but the calculator gave an answer?
No
No?
I used a calculator to check if there were any solutions and it basically just said it impossible.
Well it tells you x=-3z, and because there is no value for z it is impossible.
the two roots can be the same
you're missing the part "counted with multiplicity"
so (x - 0)^2 tells us that x = 0 is a root with multiplicity 2
Does anyone have a roadmap or website I can follow
To learn pre calc and calc
Properly simply and correctly
Without confusing shoot
Like excsersises and stuff toowebsute
Too website*
Paul's Online Maths Notes
Help me pls
OMG I thought I got banned for no reason.
What is the question asking?
Someone give me any clue about what to do please. I don't even know where to start lmao.
The exercise asks to develop (1+n)^n with Newton's binomial and derivate the result of that in order to prove those identities.
Any clue would be very helpful
Did you start off by developing (1+x)^n ? If so what did you get?
I tried to develop it as the sumatory definition of the newton's binomial, and when I tried to derivate it I almost got the first identity, but it wasn't so easy. This is what I got
I probably have made an error, but idk where
the other stuff I have are just random calculations in case I came up with sth, but that led me to nowhere
the original question starts with k=1, not k=0.
cant you use proof by induction?
Yeah I know, that was one of the things I was not sure about what to do
Probably that's the method to get the answer right, but tbh, we haven't used so much induction, so I would still don't know where to start lmao
Expand the sum and it will make proof by induction very easy.
You are trying to prove the binomial theorem correct?
Anyways, I can’t help rn, I’m on my phone. I would’ve helped earlier though but its 12am now.
I'm trying to, by developing (1+x)^n amd derivating it, prove the two identities shown in the image, I don't think I have to prove the binomial theorem
I'm not sure but I think it supposes that it has been already demonstrated
Don't worry, I'll try sth, thanks a lot
haven’t taken precalc yet
but if find f(0)
u gotta evaluate 1/2 + 2/4 + 3/8 + 4/16 + …
which is two and there’s only more choice that matches up to this
How accurate do you want your graph to be?
Because you can jus make a table of a points that lie along the graph.
If that’s the level you are at
Hmm would that matter?
I have a question that’s kinda irrelevant to that i think
basically The height of a tree in centimeters t years after it was planted, is given with the function shown
Then I need to determine grapgically the momentary growth rate after 10 years
very accurate
Honestly, I forgot how to do this without derivatives.
So if you are at the level where you can use derivatives and set the equal to 0, just use the first derivative to find the turning points, the second derivative to find the inflection point, and then just plug all those bales back into h(t).
But if your not at that point, idk.
😭
and there goes my help
I’ve tried deriving
Sorry mate
let’s just say it went horrible
this midterm went HORRIBLE
I’m so far behind it’s outrageous
I need to factorize before deriving no?
$h’(t)=-\frac{1}{10}t^{2}+5t$
TheLord26
Set h’(t)=0 to find the x value for the turning points.
oh God…
That is the first derivative.
I’m so tired rn
Bro this is my 2nd day without sleep and I just did a derivative in my head. I am relying on autocorrect to not mess up.
Yes but you’re an undergraduate or a graduate 😂
a math major perhaps
I’m a preuni student
Don’t have school rn.
also why tf would you torture yourself 😭
Sleep!!!
Are you trying to hallucinate?
Well I can’t sleep now, it’s 6:17am
What are you studying
This is a precalc channel, so precalc ig?
Anyways I’m going I don’t have the mental strength for math rn.
Lol sorry im new
Not new actually
The purpose of this server is to help you learn, not to hand out answers. Do not ask someone to give you the answer directly.
Use this property, and you'll find the answer.
whats good to study for a pre cal test ?
algebra, functions, geo, trig, exponents, logs
can someone explain?
which part?
part a pleawe
Compute the first few terms by hand -- do you see a pattern?
grows by 2n
really? that would mean the population after 1 hour would be 2,200
oh 2 to power of n
right:
stop guessing
you forgot to take away 1,000
(1110)2^n-1 -1000
how many are there after 1 hour?
wait nvm it would be 1200
yes
then 1400
now how many would there be after 2 hours?
cuz only 100 doubles i think
ok
so it has to do with derivatives
which I don't have a problem with
the problem is the fricken equation
that has a cube and a square
with a fraction
alright can i look
i'll just show you here
maybe i can help
oh that
t is 10
I get 216.666, but I can't derive it cuz the factor is hard
I should find the growth rate at t = 10
oh
just find derivative and set t=10
wait let me solve it first so i can help
will take like 2 minutes
I did that, but no avail
lim
t --> 0 no?
nah
lim
h->0
that's the limit value of deriving for growth rate
yes but t is h in this case
i mean you could say so
wait...
t is x in this case, and I wanna find the growth rate at x = 10
yes
so where the heck am I making an error?
i got 40 as value
HOW?
wait let me graph it to see if im right
That's the correct answer but i couldn't come to that conclusion
yeah
💀
t is supposed to be what youre inputting into the derivative
not the difference thing in the derivative
wdym
like
oh i was about to rewrite
yes
man...
and you have to use another variable as variable -> 0
nah you dont have to pull a limit trick