#precalculus
1 messages · Page 280 of 1
I can show you how to do it on wordmat
ok
so this is what I get
first you make a table like the one in the picture
and then you choose the wordmat tab > regression > exponential regression
and you get the following equation
huh
Hm
Do you know how to do it on a graphing calculator?
I have to find the a and b values though
yes you can see the a and b values in the equation
I need a graph though
kyoto
ok
you can plug the equation in your graphing calculator
but I can see in your case the form is:
$y=a \cdot b^x$
kyoto
so what's the value of a and b here? @viscid thistle
I don't even know so confusing
look at the picture I sent
Can you show me it on paper @vestal zenith over text is hard
Ye
Idk how you got those numbers though
in the progress
it's a bit hard to explain when you're not used to wordmat
and i'm wondering why your teacher haven't taught you how to do regression yet
i'm not familiar with desmos but I found a video about it here: https://www.youtube.com/watch?v=zcZaI-xfiFE
This video explains how to perform linear regression using the online graphing tool Desmos.
http://mathispower4u.com
ok ty
anyone help me with velocity problem?
is there such thing as the inverse of a factorial
like how division is the inverse of multiply
can someone simply explain the reasoning behind why floor(-x) and -floor(x) are different
which part are you stuck on
@thorn agate
have you learned about derivatives?
if not have you learned anything about exponential growth
rate of growth
thats just a derivative
sapphire grows overtime at a declining rate
thats also a derivative
also this is a precalculus channel btw
I need 7, or 8
can someone plz help
do you have any notes?
@lunar axle
this is usually what youll use for C -> P
obviously youll need to simplify
r means radius
yes.
yeah
yes, as it has changed cot into 1/cot which is wrong.
Would the quadratic function be A(x) = 6^2 + 12x + c?
not even sure
@astral knoll
Area=width * length, so new area is (6+x)(12+2x), now multiply and u will get the result in the form asked.
for a question like this
are we supposed to assume that the right triangles evenly share the height of the pole
so like each side thats adjacent to the pole is 15 ft
or am i getting that wrong
bruh
divide it by 2 then factor
Probs not
Since they got different angles
Try treating the whole system as one big triangle by adding the two angles
You know the height of the base
And the angle of one side
Crap actually nvm then u can’t use trig
What have you tried so far?
well im just wondering what am i supposed to do with A, B, and C
plug in -2 into the equation
-1 if x<0
-1 if x is greater/equal to 0
soo the 1st part is true but the 2nd part isnt
yeah
what part of this are you confused about?
if x=3 then h(3) = 6
otherwise, just substitute x into the other equation
also note that the other equation simplifies to x+3 if x is not 3
help pls
@quartz oxide do u still need help?
ok, do you remember solving quadratic equations during Algebra II?
yea kinda
okay great, so simplify this let's just refer to this as $3x^2 - 7x + 2 = 0$
Jitter
do you know how to put the equation into factored form?
would it be (3x-1)(x-2)=0
Jitter
we can set each equation equal to zero, getting the equations $3sin(x)-1=0$ and $sin(x)-2=0$
Jitter
so is that the solutions for [0,2pi]?
Well, you can simplify it and find an exact value by solving for $sin(x)$. first equation would be $sin(x)=1/3$ and the second $sin(x)=2$
Jitter
I need to solve for x (the original problem is circled). Below the problem is my work so far, but I’m stuck on how to get the x’s on one side of the equation. My teacher wants us to provide the exact solution and an approximate solution.
Ok, what did I do incorrectly? And how do I move the x to one side?
u have to expand the brackets when it first appears
then move all x term to one side by addition/subtraction
then factor out the x
sorry, how do I expand the parentheses?
(x-1)log2: x log2-log2
yes!
Thank you!
but not done yet
Yeah. Where do I go from here?
step 3^
By factor it out do you mean divide?
2x + 4, factor out 2 becomes 2(x+4)
Ah ok
factor means take out common factor
looks good
yes
What do you mean..
Never mind I figured out my own question
Alright then
@iron pendant
how would i answer this?
polynomial of degree n will have nth differences be constant @agile owl
im not sure what that means
Lines (degree 1 polynomials) have constant 1st difference
quadratics (degree 2) have 2nd differences constant
etc
oh ok then that's degree 4 cuz its x^4?
yes
that makes sense thank u
the word differences messes me up
then this would be 3rd differences cuz its degree 3?
yes
how would i find what number it is?
d = an! @agile owl
d=4(3!) ???
yes
Can anyone help me solve this question? "A balloon drops 2 balls with a time of 3s between the drops, after 10 seconds the first ball reaches the ground, how high is the balloon? (tag me if u can help me out)
anyone?
Hello
I am Solving a exponential function. I’m at 4^2x+9=12
So after subtracting nine on both sides I end up with 4^2x=3
What would be the next step ?
you would take log, base 4, on both sides
So log each side ?
yup
Ok thanks a lot I was stumped on that and was unsure on what to do
Logs are so confusing
the rules may take some getting used to
but it is fine more exercises or examples will treat it as 2nd nature
Indeed I’m still getting used to them after a week of practice
perfectly normal take some breaks in between overwork will prevent you to have the "aha" moment
Do you know what is sec x equal to?
@oak skiff you need to use this arcsinu + arccosu = pi/2
infinite, question is not well defined
hm
wouldnt that be ambiguous case
then you use law of sines to figure out the sides and angles*
you can determine whether it’s obtuse or acute right after
it says i have to pay for steps :c
hm
it gives answer but idk rly how to do it myself
lets see, uk how they give you steps but its incomplete
you could open it on another tab and put that part where it was incomplete
then it shows you the steps on how to complete it
@misty imp
I had that trouble back then too
lol
ic
x + 3y = 12 and 3xy is as big as it can be. First thing to note is both numbers have to be positive : if only one is negative so will the product, but if both are negative the sum cannot be 12. Next to try and find y you might want to consider all multiples of 3 smaller than 12 and compare against a necessary x value. Compare these products and take the maximum (this is assuming the question wants integer answers)
Okay thanks
@misty imp check out the laws of logarithms. For this problem in particular pay attention to the product rule and quotient rule
i found the angle measure using inverse tan but what do i do after to find the weight?
i think u have to resolve the force/tension in the diagonal cable to balance out the horizontal force and vertical mass
how do i find the answer do i plug in the coordinates?
you can plot the function in your graph calculator and check it
Huh?
That's not even close to the method they probably want them to approach this
@agile owl consider how can you express that a number is negative first
f(x) < 0 means f is negative
yes
I was trying you to go "to express a number to be negative, x<0". Then you'd go f(x)<0
-infty?
anyone free to vc to help me with 2 problems?
hey, how do i find the root of a non-factorable cubic equation?
the equation is: P(x) = 5x³+21x - 2
the presence of 14x and 7x separated like that is very suss
are you sure its not supposed to be 14x**^2**?
because that would have nice roots
nopee its 14x + 7x
prolly, but its still solvable right?
,w solve 5x³ + 14x + 7x - 2 = 0
this is what i got when i assumed 14x as 14x²
solveable yes, but very ugly
i think i'd go with 14x²
use cubic formula and/or depressed cubic
yeah it looks ugly
will cardano's method work?
fancy name related to what i stated
when finding non-permissible values of a rational expression, only the numbers on the denonminator is what you're working with, right?
Yes
for rational expressions, the numerator would be defined everywhere so yes you only need to consider the denominator when determining non-permissible values
Alright, thanks!
how do I find the polynomial equation using the quotient and remainder?
its better if you post the whole question
okay, uh, "Write a polynomial division that has a quotient of x+5 and a remainder of -2"
consider the quotient-remainder form:
P(x) = (x-a)Q(x) + R(x)
ahh that one! thank you
Hey all, is there a reason to use cardans method to solve cubic equations? Im using the "a0/an" method that I've seen which is easier. If it's worth the time, I'll learn the cardan method
well use whatever can be used to solve, there is no set method. Studying Cardano's method is useful nonetheless, because sometimes the usual techniques don't work , it is a method to find the real roots of general cubic equation so sometimes does come handy, it is kinda like the quadratic formula method.
Does cardano's method always work?
Also, do cubic equations come up in calc 1 or 2?
I was having trouble finding a video to explain cardano's method; most of them are in hindi, and I've yet to learn how to speak it
I think this is enough, just write cardano's method , and a load of stuff is on internet in english
@scarlet oak
Thanks! I'll definitely check it out. @cobalt swallow
given a recursive sequence definition
lets say you want to find like the 4th term
is there a way to find just that one term, without having to start from the first term and progressing until you reach the 4th?
ye there is a way
well
should be obvious that
every term is you just adding +3
to the number
so you want 4th term. just multiply the 3 by 3
add 9 to 15
you get 24
yeah
yeah i just verified it with some python
do you know what the recursive definition for this sequence would be?
Hmmm, there might be many.
If you assume the form of
a_n + A a_n+1 + B a_n-2 = 0
Inputting exact figures, give you 2 equation of 2 variables, A and B.
@tribal vapor
It's a classical recursive formula with 3 terms
You can have more or less terms, but this is like the most common one.
You can have for example
a_n + A* a_n-1 = 0
Solve the trigonometric equation for all values −3π≤x≤3π. 2sin1/3x-sqroot3=0
hi I'm in elementary school how do I start learning calculus now I want to make my paretns proud
expressing something in base $\red{a}$ would mean to express it in the form ${\red{a}}^b$
ℝamonov
so for b for example its 2^64^2-x?
no
@past meadow why so?
Because 2^64^2-x doesnt equal 64^(2-x)
And its also probably not even what they meant to write
I'm assuming you let 64^(2 - x) = 2^a, and solve for a in terms of x
for problem (b)
same for problem (a)
but just 3^a
suppose the graph of y=ax^2+bx+c has its highest point at (1,7) and it's y-intercept is -3. Then what is a, b, and c?
@quick kelp are you still stuck?
Consider what happens at the y-intercept
ie what's the x value that characterises it
Ok yeah ig you could think it that way
If you are in the form y=ax²+bx+c yes, as when the function hits the y-intercept, x is 0, so you'd notice that y=a(0)²+b(0)+c simplifies to y=c
ohh
Then what's our c?
the y-interceptt
I mean what's the value of the constant c
y?
You are given the y-intercept, aren't you?
yes
If you know the y-intercept, and we just established that c represents the y-intercept, what's our c
ohh!
What can you do with the info: "highest point at (1,7)"
Yes
And you get an eqn
Our goal is to make a system of 2 eqn's to solve for a and b
What's the other equation you can have
hm..
Think about highest point
(h,k)
Think about what does that mean
vertex?
Do you know how to get the vertex if you have for example y=x²+x+1
This is just an example
do you use an equation form?
I want to see if you are able to do it numerically
Wdym by eqn form
Uh i really have to go, i'll be back in some time
Ok gl
@quick kelp if it can help, recall that the x coordinate of a vertex (in the form ax^2 + bx + c) is -b/2a
Yes.
how would this vertex equation be relevant if i may ask>?
Because now you have 2 equations
The one you got by plugging (1,7) into the rule
And the one you just got
You can find a and b that way
hm...
let me think this through
i'm so sorry I don't know how to continue
so I got 2 equations which is 1=-b/2a and
y=ax^2+bx-3
7=a(1)^2+b(1)-3?
Ohhh
okok im solving it rn
what I did
I got the value of a from 7=a+b-3
which yield to a=-b+10
then plugged the the value of that a to 1=-b/2a
and got a b=20
and used that value of b again to 1=-b+10
so i got a=-10 b=10 c=-3
b=20*
Looks good @quick kelp
Oh my god
thank you so much
thank you to both of u! Really appreciate the help!
And the time you gave for a stranger :))
https://notevensweating.shx.gg/sbwmhP i got this problem wrong but i dont understand why, can someone explain and help me find what i did wrong?
@iron pendant are you familiar with unit circle?
describe what you did
can someone plz confirm if this is right for me??
Looks correct
If your question has not been answered for a minimum of 15 minutes, you may use the Helpers tag once. Please do not try to bump your question using this ping unnecessarily. Do not abuse this ping. Do not individually ping users with the Helpers tag without their express permission.
we can do some algebra then recognize a derivative
I have no clue what that means
$\frac{1-2\cos(x)}{\pi-3x}=\frac23\frac{\cos(x)-\frac12}{x-\frac\pi3}$
RokabeJintarou
you're welcome
it is not that the answer is wrong but the way you did it, firstly you seem to have used the fact lim x-> 0 sinx/ x =1, nothing wrong with that , but your second step is wrong, in the way that it does not lead to third step the way you did it , to get to the third , you don't do multplication in sin, rather you do it outside sin, and that you will multiply by (m+n)(m-n)/4 , both above and below ( I repeat outside of sin) , then you will get the third step as you have
@bleak torrent
and after that you use lim x-> 0 sinx/ x =1 , so the third step expression will directly be as k^2 will cancelled when you use that fact , so -2 (m+n)(m-n) /4 =
-(m+n)(m-n)/2 the answer you got ,
Hey! I'd like to simplify sqrt(16+sqrt(31))-sqrt(16-sqrt(31)) into sqrt(2) but I don't know how to proceed! Does someone have an idea? Thanks!
you could try assigning a variable to your original expression,
square it in an attempt to simplify some of the square roots and see what happens
hi hi. quick question.
i came across this identity in my book, is there a name for it?
$a_0=0, {\sum_{i=1}^{n}{(a_i -a_{i-1})}} = a_n$
Biggs
Hi, I'm a little confused on how to do this type of question:
The point (1, -2) is on the graph of f(x). Describe the following transformations on f(x), and determine the resulting point:
g(x)=2f(x)+3
@odd shell do you have the transformations from f that make g?
@sick steppe yeah that is why i am confused
this is the only information that is given to me
ok so what does the 2 do? and what does the +3 do?
well so the 2 would be a vertical strech? and the three a vertical translation up?
yep
vertical stretch by a factor of 2, vertical translation 3 up
Now determining the resulting point means you want to know g(1)
but g(1) = 2f(1) + 3, but f(1)=-2
so then would it be g(1)=2(-2)+3
yes
yes
0/0 so L'Hopital's rule
consider 1 = sin(pi/2)
and the limit definition of the derivative
hello can anyone help
a. 1st derivative
Shen
ok thanks
ax^2+bx+c
c determines the height, changing this doesn't change the maximum height?
it doesn't change where the maximum height is
$x = \frac{-b}{2a}$ is where the maximum is
Shen
according to a quadratic in the form $ax^2 + bx + c$
Shen
changing $c$ changes the max value, it just doesn't change where it is (along the x-axis)
Shen
If you want to solve for maximum height, you need to do:
$a(\frac{-b}{2a})^2 + b\frac{-b}{2a} + c$
Shen
where you plug in $\frac{-b}{2a}$ for $x$
Shen
help
use the arithmetic series formula $\frac{n}{2}(2a+(n-1)d)$
187
how do i do the sum 165 part
let it equal to 165
then you know the values of a and d
a=5 and d=2
so solve for n
187
bro how
im stuck on this question
i tried finding the inverse but i got stuck trying to isolate
So the input of ln can't be negetive or zero i.e it has to > 0
\begin{align*}
e^{x^2-x}> 1\
\therefore \hspace{6pt} x^2-x>0\
\end{align*}
So that gives either x=0 or x=1
S k
how did you go from e^x^2-x > 0 to the second one
removing the e
and how did it go from > 1 to > 0 @signal pivot
i dont understand how to jump to that step
e^0=1 @bright grail
Is there a reason why during addition identities and subtractions for trig functions, when you break up the inner values, it has to be from the lower value to the greater value?
@woeful fable specific example if possible?
cos(2pi/12+3pi/12) != cos(3pi/12+2pi/12)
I did the angle formula
and they don't equal the same unless I have an algebraic error
I did cos(pi/4+pi/6)
Which sums just
cos(pi/4)cos(pi/6) - sin(pi/4)sin(pi/6)
yeah
That's equal to (sqrt2/2)(1/2) - (sqrt2/2)(sqrt3/2)
then that's sqrt2/4 - sqrt6/4)
which is sqrt 2 - sqrt 6 / 4
brackets
wdym
(sqrt2-sqrt6)/4
I just distributed and simplified
yes
yea
And that's not equal to what it's supposed to be
if I did cos(pi/6+pi/4)
The top one is my result
the correct answer is the bottom one
You either added or removed a negative somewhere then
cos(pi/4) = sqrt2/2
cos(pi/6) = 1/2
sin(pi/4) = sqrt2/2
sin(pi/6) = sqrt3/2
angle addition formula for cos(x+y) is cos(x)cos(y)-sin(x)sin(y)
idk where im screwing up
Result:
0.86602540378444
,calc sin(pi/6)
Result:
0.5
0/0 so L'Hopital's
@bold meadow I am trying to work this out on my own but I am not understanding the step by step for e
well after using L'Hopitals' you can see that it just becomes:
$\lim_{x \to a} \frac{\sec^2{x}}{-\sin{x}} = - \csc{a}. \sec^2{a}$
usernamephobic
@bold meadow in my book it says f'/g'
so I need the derivitive of (tanx-tana) as step 1 to find f'
derivitive wrt x
but there is an a there
Divide numerator and denominator by (x-a) and you'll notice that each term becomes the definition of derivative at x=a
ok that matches the book
probably harder for me because I forgot the definition of a derivitive
isn't that just the definition of the limit of the tangent line?
slope of the tangent line
$f'(a)=\lim_{x \to a} \frac{f(x)-f(a)}{x-a}$
My Army is Frozen
ok thx
Need help solving f(x) = 0
the solutions aren't pretty
there is 2 solutions only , that can be seen for -2e^(-x) = x-4 by "hand " drawing the graph
but yes finding them won't be easy
using W lambert is a good way to solve it
Can you show me how?
it gives solutions W( ...)+ .. something, they are expressed in terms of the Lambert's function , but we need numerical values I don't think you need it, considering you asked it in precalculus
I don't know how to do it properly as well
Only looked it up when Ramonov told about it, really interesting.
many find approximate solutions through iteration
maybe using Newton's method
Hmm... I’ll try using Newton’s method
blackpenredpen on youtube does the W-lambert functions method
can someone explain this? how did they get this
they used the lengths of the line segments
desmos proves this, but how would you get this without the use of a graphing calc?
divide the red inequality by sin theta, then take reciprocals (which flips the inequality signs)
Have you tried anything so far? @winged cloak
@viscid thistle Nvm i did it it was dumb 🤦♀️ i just couldn't see it
Can someone help me with: Graph the function f(x) = cos (x) and g(x)= 1/2 cps (2x-pi) ?
What do you know about the graph of y=cos(x)
Suppose you need to find the height of a tall building. Standing 20 meters from the base of the building, you aim a laser pointer at the closest part of the top of the building. You measure that the laser pointer is 4◦ tilted from pointing straight up. The laser pointer is held 2 meters above the ground. How tall is the building?
Draw a diagram
and
Show your diagram
^
If your diagram is right, it's just a trig question
can u help me with the diagram im confused
not much im generally confused about this
ok, my recommendation is imagining it in your head. Imagine a building, and you walk 20 meters away from it. Now draw one line as the building, and the other line as the path you took 20 meters away from it
Got it so far? Now I recommend drawing a line from the point where you currently are to a point 2 meters above it. That is to simulate the laser pointer
ok
Now draw a line connecting the laser pointer to the building
And show your drawing, even if it's not done and you need help to continue
i think you were the one i was helping who i asked for the diagram but you didn't post it
Maybe their phone is too old to take pictures and they're embarrassed to tell us
Don't be, only the mods here are elitist. The rest of us are nice.
i have the iphone 11
I just need help with
Graph the function f (x) = cos (x) and g (x) = 1/2 cos (2x-pi)
i also said "what do you know about y=cos(x)" previously answering this q and you ignored it or i skipped it
You've never heard of cos before and know nothing about it?
Do you know its graph?
f(x) and g(x) are two different functions
So therefore 2 different graphs?
You need to know how to graph cos(x), and then apply transformations to it to graph 1/2 cos(2x-π)
... Yes
Yes, I don't have a lot of time to help. Hopefully someone else can
Glad you can send pics now, that will help
if that's supposed to be the graph of y=cos(x), then sure that's fine
though it seems you took a pic from desmos
...
So you just wanted help on how to enter it into desmos?
Yes and No
huh
Because I’m not sure if there’s supposed to be on one graph or two different graphs
So now I just to graph g(x) on a separate graph right?
OOOOF
Me who still hasn’t figured out mobile desmos
don't blame you - computer is better ngl
@viscid thistle stop crossposting
Suppose your making a bioweapon that kills 1/3 of the population.
But you & your secret organization of 9 people decide to immunise prior.
If people realize that 1/3 of the population didn't die they'll know you have the vaccine.
How do you change the kill rate to ensure the 1/3 of the population still die even after 10 have been immunised?
Supposing the population has 90 people, in normal circumstances 30 people would die.
But you want to change that so 30/81 people will die.
So the formula is like (population*ratio)/(population - vaccinated people)?
Does this check out?
@viscid thistle not sure what you are asking... oh, you want to change it to kill 30/81 of the people? looks reasonable...
yea so it doesnt look suspcious when 9 of the 90 people in the population are secretly immunised
I know that logs aren't defined for negative numbers
but is there any other reason as well we can't do this:
ln(1)=0
ln(-1.-1)=0
ln(-1)+ln(-1)=0
2ln(-1)=0
ln(-1)=0
let ln(x)=c, x<0 and c belongs to R
e^c=x
which is not true for any c belonging to R
well its not that it isnt defined
but it isnt defined in the real number set
but log of a negative number can also be defined by a complex number
I'm not sure if this the place to ask this
is there a precedence rule for factorial and multiplication?
$3n!$ is $(3n)!$ or $3(n!)$?
az
i think its the latter one that is more common
factorial takes precedence over multiplication
thanks
np 
nice
you thought they were lying? smh

i mean ! is unary operator
!n! what ! comes first?
The exclamation mark
smh !n is subfactorial
Whoa never knew that
How
How do you solve this system of equations
Parameters are p, q, r and unknowns are a, b, c
What's troubling you with this system?
It can be solved by any standard methods for solving linear equations
Gaussian elimination will work just fine here for example
How would you go about solving #13, just for sine (without calculator).
<@&286206848099549185> sorry it's already been some time
$\sin{-115}=\sin{-25}=-\sin(25)$
usernamephobic
Thank you. However, I need to obtain a ratio as an answer, so how would that be done. My teacher had not gone over this type of scenario, where the reference angles are not common like 30, 45, 60, or 90 degrees.
-sin(25°) is exactly what they want
the less special angles are 15°, 36°, 72°,75°
I see
i mean if you read the question, they want
stuff in terms of trig functions of the reference angle
so even IF you reference angle would be 30°,
you'd give an answer like -sin(30°) instead of -1/2
I can't do it for some reason..
@maiden pelican , just solve it the plain elimination way, Using equation (1) and (3), cancel out p, getting an equation in q and r, which you can solve using eqn(2). Doing by gaussian elimination is really quick
Yeah.. I can't do this for some reason, something is going wrong and I don't understand what..
Oh I'll do that
the problem does not ask for a ratio
Yeah I was overthinking it, because I thought it correlated to earlier sets of directions from another worksheet
Oh I see
@mighty talon Bruh, did you join just to spam your dumb competitions in every channel daily?
Doing @ Moderators might be worthy here
Idk how they could have missed it
I will do it for you.
<@&268886789983436800> - can we deal with an ad user here?
how would you determine the function given this table of values?
im stuck someone please help
infinite
First thing you can do is figure out which of first,second,third, etc differences are constant
Would someone explain the concept of an infinite geometric series quickly please? Specifically its difference of finite geometric series?
infinite geometric series go on forever, they have infinitely many terms
finite geometric series stop at some point, they have finitely many terms
does that answer your question? @median moss
I understand that part, I guess I should be more specific. I don't really get the divergence and convergence part. What role does the common ratio (r) play a part in the sum doesn't really click for me, even though its written there
well, imagine trying to calculate that sum 1 + 2 + 4 + 8 + ...
by hand
it will just get bigger and bigger
yep
it basically goes off to infinity
but when you have a sum like
1 + 1/2 + 1/4 + 1/8 + ...
since the terms are getting smaller and smaller
the more you calculate, the slower it will ‘grow’
so it will approach some specific value
the terms r^a get smaller and smaller when you have the ratio between the terms is less than 1
Ahh I kinda get that, and it depends all depends on the common ratio I guess
anything multiplied by a number less than 1 will be smaller
Give me like 10 minutes to just sit on it and try to actually understand and come back to you :)
Thanks so much
anything multiplied by a number greater than one will be bigger
so in order for the terms to get smaller and smaller, you need to be multiplying by something less than one each time
ie r < 1
(at least for positives :p)
Ah got it, and because they get smaller term by term. The sum of these terms will just converge to a sum
not because they get smaller term by term @median moss
it's due to the properties of geometric series - "how fast they get small"
for instance, 1 + 1/2 + 1/3 + ... gets smaller
but doesn't converge
yeah, it’s quite subtle. for all geometric series, ‘they get smaller’ is a good enough intuition, but in general you can have a sum whos terms do not get small fast enough for it to converge
I'm probably using the terms converges and diverges loosely as its a calculus term and i haven't done limits yet. So sorry about that
no dont worry, i just glossed over some details in my explanation
@sick steppe yea the third differences are constant
but what after that?
i know that one of the factors is (x-2)
but thats it
I guess just use the points and try and find f(x) @odd shell
Functions nice!
Anybody here willing to teach me factoring tomorrow?
what sort of factoring?
integer factoring or polynomial factoring?
teach me how to factor integers in polynomial time
I don't know, but I can teach you some O(n^(1/3)) and O(n^(1/4)) methods
n is the number to be factored
not the number of bits
oh right
Poly
oh no polynomial factoring
https://en.wikipedia.org/wiki/Factorization_of_polynomials
this is crazy stuff
In mathematics and computer algebra, factorization of polynomials or polynomial factorization expresses a polynomial with coefficients in a given field or in the integers as the product of irreducible factors with coefficients in the same domain. Polynomial factorization is one of the fundamental components of computer algebra systems.
The firs...
do you have a class of polynomials you want to learn how to factor, or do you want to learn how to factor polynomials in general?
whoa LLL is crazy
this might be something really obvious but how would I work out y - 1 as a function of x? Would this be written as f(x) = y - 1?
If it is, then I'm really lost. X is the inputs right, but the x's aren't being mapped to anything so how would there be a solution?
Do you have an exact question you are looking at?
yep
The original question was find an expression for the function whose graph is the bottom half of the parabola x + (y -1)^2 = 0.
The hint was can you solve the equation for y - 1 as a function of x?
I'm a bit confused about the hint. (Also I wasn't tooo sure where to ask this as I'm starting calculus at uni but these were meant to be prerequisites)
Ping me if you come back
@echo wagon i'm here
Okay, so you just have to isolate y in the equation
Make y the subject
So what do you think the first thing you have to do is?
for the hint? How would I make y the subject if its currently f(x) = y -1, would that not be y = y -1
for the equation in the original question, i could rearrange and make y the subject
actually, i think i tried that but i got stuck at y^2 - 2y = -x -1 when I tried to make y the subject for the original equation
No
The equation is x + (y-1)^2 = 0
Isolate y in this equation
Oh, okay, you did do that
Didn't read all of it
What's the first step?
ahhh i think i get it! So (y-1)^2 = -x , then square root the -x and add 1?
but can we square root the -x?
Yes
Why not?
x+(y-1)^2 = 0 doesn't have solutions where x is positive, so x <=0 and -x >= 0. So you are only taking the square root of nonnegative numbers
what if x is positive, then we would be square rooting a negative number no?
ahhh
that makes so much sense!! Thank you so muchh!!
But you're not done yet
im not?
What are the solutions to x^2 = 4?
plus and minus 2
Right, so when you take the square root, ordinarily you should do +- in front
ok so i have 1 +- sqrt(-x) ?
But y = +-sqrt(-x) + 1, isn't a function because it gives you TWO values of y for one value of x.
ahhh i seee
Whereas a function should have one and only one value of y for each value of x
so just -
ahh, got it! Thank youuu :)))
Np
U knw wut this server is friggin boring im leaving
ok bro have fun
the pink goes with two consecutive even whole numbers
adding two to a whole even number gives a whole even number
well so does 4
if a function is a set of ordered pairs no two of which have the same first member, how are two to one functions functions?
wouldnt the first member be the domain?
x and x+4 wouldnt be consecutive if x is even
consecutive means right after each other
Ohhh
so 1 and 2 are consecutive numbers, but 1 and 3 arent
The question states consecutive even numbers
so if we assume x is even, the next even number is x+2
since even numbers occur every other
you can also think of it as 2n and 2(n+1) for an integer n
I need some help visualizing this problem and drawing it out
We just started these today and all I can do is draw the first part (12 nautical miles)
anyone?
then you draw the 15 nautical line from where you ended
this is vector addition
@robust nest 12 mi is the hypotenuse of a triangle
N60W is the angle of theta with respect to the y axis
,w 12e^(i*(5pi/6))
see the decimal expansion is actually your x and y values
drop the i
if you do this twice you will have (x1,y1) and (x2,y2)
then if you do (x1+x2,y1+y2) which is the sum of the two vectors which is a vector that represents the relative location (final) compared to your starting location
hi can anyone tell me the steps for the answer?
it has already been solved on a calculator
,w sqrt(0.688)
,w sin((236/360)*2pi)
then we want to convert that % to radians
1 full rotation around a circle = 2pi radians
so I multiply by 2pi after I do /360 to get the conversion from degrees to radians
360 deg = 2pi rad
@mystic umbra how can we get that when we don't have calculator ?
For this question, why is the answer 3? mostly the f(0) could take any value part
Well, if f(0) = k then because f is even we get f(-0) = k and there is no contradiction. But if g(0) = k then g(-0) = -k and this only works if k is 0
@open vortex
Ahhh I get it now, thank you :))
Np
if a function is a set of ordered pairs no two of which have the same first member, how are two to one functions functions?
wouldnt the first member be the domain? << don't mind the repost im just still confused on it
@viscid thistle A two to one function just means that there are two different first coordinates that give the same second coordinate
So the first coordinates are unique, the second coordinates are not
{(0, 1) (1, 1)}
ohhh for some reason I thought the second coordinates would be unique cause it's one i'm so dumb 😂
that's when it's injective
,w limit x->2 (x^3-8)/(x-2)
so this can only be done by factoring?
You can use Lhopital's too
actually no
that is for the derivative right?
there are times when the limit exists but the derivitive does not exist
you can have a limit of 0
lhopitals works because you are dividing by 0
is hopital's rule for limits or derivitives or both?
limits of indeterminate form
Lhopitals is to find limits, by taking derivatives.
ok

What do you mean by dividing?
$x-\frac13x^4-6x^2+17x-8$?
ℝamonov
Because the degree of the numerator is already smaller than that of the denominator
$\frac{x-1}{3x^4-6x^2+17x-8}$
Star_
?

