#precalculus
1 messages · Page 44 of 1
By the way
2^x - 3^x = - 1
So can we say that lhs is monotonously decreasing function?
no
with calculus
So cant i solve precalculus exponential equations without it?
I mean, hard ones
if you can show that x < y implies 2^x - 3^x < 2^y - 3^y or that x > y implies 2^x - 3^x > 2^y - 3^y, then you will prove that the function is monotone
f:g:h g is 60 percent more than h , f is a third of g , simplify f:g:h
Hello! Idk where I can ask it tbh, because it is a simple thing. Is there a general formula for derivative of f(x)=u(x)•v(x)•w(x)•…? I mean I can find the derivative of the ‘triple’ product, it isn’t that hard but is there a general way? Because if I would have to find the derivative of the of 6 functions, I will spend a lot of time counting a lot of default derivatives for the product of two functions
~~ see this: https://en.wikipedia.org/wiki/General_Leibniz_rule ~~ nevermind, I made a mistake
(also, this belongs in #calculus, but no big deal)
I made a mistake, the first link shows you show to differentiate a product of two functions n times
the second link gives you the derivative for 3, and then k functions
just below that, you can also find out how to differentiate a product of k functions n times
there's also stuff for partial derivatives, but I'll let you explore all of that lol
Thank you so much!
I haven’t got calculus because, I think, I have only got pre-university group… my bad with it
give yourself the Advanced role
type ,iam advanced in #bots
that should let you type in #calculus, and the other early uni/adv math channels too

oh, you've taken the UG role
that works too!
Thank you!
I just got the AoPS Precalc book and I'm stuck on trig unit circles :-: does anyone know the basics to it?
that's not nearly a specific enough question
try again
what don't you get about it?
Hold on lemme find a picture
ok so for example you have graph sinx=sin(x+2π)
and it asks if it's periodic and if so find the period
how am I going to solve this question?
Having trouble understanding why multiplying the x value in a trig function, decreases the length of a period.
It just doesnt make logical sense to me. I feel like it would make more sense, for it to be reversed instead of 2pi/b.
Why not just 2pi * b, since you would be multiplying the input x value?
trig functions aren't special
@bronze rock Thanks for the explanation! I think I got mixed up lol
f(ax) represents a horizontal dilation of f(x)
when |a| > 1, the function is compressed; when |a| < 1, the function is stretched
Yeah I just find it super odd that its a dilation I guess. It just seems reversed logically to me
wat is
multiplying the x value of a function.
Its Inverse Variation which I find weird
Suppose f(x) is periodic with some period and consider g(x)=f(2x).
Then you only need half of the x before g starts repeating.
Since multiplying by 2 means you can reach a certain input for f without spending as much x as you would need to if you fed x directly into f.
Ah I see. That makes sense. Thanks
oh ur talking about why 1/a is a stretch but multiplying by a is a compression
im guessing
ya does seem p reversed
you need calculus, more specifically take the derivative and sub in the x-value of your point
i need a bit of help with precal
the question is "graph f and g on the same set of coordinate axes (include two full periods)"
!da2a
No need to ask “Can I ask…?” or “Does anyone know about…?”—it’s faster for everyone if you just ask your question! See https://dontasktoask.com/
oh ok
f(x) = -2 sin x
g(x) = 4 sin x
i kind of forgot like everything so im struggling with how to graph individual ones
can you graph y = sin x?
like what's sin 0 for example
i have the graph memorized
but like im still kinda new on the entire concepts of graphs and stuff
sin 0 = 0?
oh right, that's good then
yes!
so you need to watch a video on graph transformations then
what the -2 and the 4 do when multiplied by sin x is that they stretch the y-direction
so 4 sin x stretches the y-direction by a factor of 4
in other words the max is now 4 and the min is now -4
ohhhh
-2 sin x is similar but after you stretch the graph by a factor of 2, you reflect it across the x-axis (flip it upside down)
you flip it upside down when there's a minus sign multiplied by sin x
wait so it's like normal rules of transformations
exactly
okay wait that made so much sense
cool sounds like something didn't click for you and that you actually know your stuff
thank you for the help 🙏
looking for some hlep in studying for cal final if anyone is interested
What sort of stuff is it?
What does it want me to say when it asks for an explanation for my reasoning
why do you conclude the answer that you do?
(if it’s a polynomial, just state the parity of the degree (even/odd) and the sign of its leading coefficient (positive/negative))
ok
hi could anyone help me with this series problem in this thread?#1252945019342557204 message I cant ping helpers there due to this:
Hey could someone help me with this one question
!da2a
No need to ask “Can I ask…?” or “Does anyone know about…?”—it’s faster for everyone if you just ask your question! See https://dontasktoask.com/

#calculus is a better channel for that 
right, you can't see that channel, can you?
take the Undergraduate Math Role in id:customize
that's good enough
the role is meant for people who study undergradate math
you don't necessarily have to be an UG for it
many are not

#calculus is the channel for calculus discussion
this one is suited for precalc
I need to solve for the critical values of cos(2x)+sinx+1=f(x). I set the derivative equal to zero and got 0.25 and 2.9. However, there are two other critical values that I don't understand how to get mathematically.
there are infinitely many critical points, not just two or four
you need to show your work
How far does pre-calculus go? When does it end? Like- i took the 5 rules of derivation and some integration techniques, am i at calculus 1 or pre- calculus
The last two lessons i was taught: how to differentiate trig functions and applications on derivatives
Next year first two lessons:how to differntiate functions in parametric form and implicit differentiation
you are most definitely in calculus, not precalculus
take the Undergraduate Math role in id:customize, and then go to #calculus if you have calculus-related problems
this channel is for the usual precalculus curriculum
I did i did (i usually ask questions in help channel) ok ty higher
Higher is like
The infinte version of high
higher! 
You cant get higher than higher
I don't see your UG role, strange
So higher is infinity
Oh? Lemme check
🤩
ermmmmm technically akshually calculus is Pre-uni and not undergrad 🤓
depends on the school
the graph looks mostly okay, but 3^4 = 81, not 51 like you've plotted
If two men are moving towards each other, the first one with speed 10 m/s and the second one with speed 7 m/s, how soon will they meet
And the distance between them is 100 m
I dont understand how to solve this kind of porblems
100/(10+7)
If they move towards each other u add the speed
If they leave each other then subtract two speed
Hello
I think i should replace 4x (i dont have theta character in my keyboard) with t, so the equation is gonna look like this: cos t + cos 2t + cos 3t = - 1
Is there an easier way of solving this equation without cos 3t identity?
I mean i always confuse cos 3t identity with sin 3t identity and it's hard to remember it to me, so maybe one can solve the equation without it?
Thanks, but the equation has more solitions as far as i remember
I solved using cos 3t identity
However thanks, i should learn sum of cosines identity
yea it would have more, but keep in mind that theta is between 0 and pi/2
do the numbers look correct?
,w log_3 (17)
,w log_3 (36)
I don't get how you came up with those values
you just draw horizontal lines y = 17 and y = 36 on your graph
cause $3^{\log_3 17} = 17$ and so on
southy
no worries
log 3 (17)is 1.707 though
it's not
and you shouldn't get that value from your graph
should definitely be 2 point something
no worries again
so it gives me 2.5 but how do I graph it?
oh, type in 3 ^ x
and then you can type in y = 17, y = 36 on different lines
how did you get 17 and 36?
the question says 17 and 36 here
how do i prove that the derivative of sin x is cos x
The differentiation of trigonometric functions is the mathematical process of finding the derivative of a trigonometric function, or its rate of change with respect to a variable. For example, the derivative of the sine function is written sin′(a) = cos(a), meaning that the rate of change of sin(x) at a particular angle x = a is given by the cos...
at least take a few seconds to google it first
use the limit definition of the derivative
and the sin addition formula, $sin(x + h) = sin(x)cos(h) + cos(x)sin(h)$
KJ
I see several identities at the same time, but it didnt help me at all
I just dont even know what should i start with
I tried expanding sin 4x and sin 2x but it was still useless
You know the sum to product identities?
Wait are you trying to prove this or find solutions?
Cuz if prove then its not possible as the statement is wrong (look at x=0)
It's an equation
I am trying to solve it
Yes and i already applied it
What did you get
i got 2sin(x)cos(3x) = 4cos^2(x) -3
Expand cos(3x)
As sum of 2x and x or as a cosine of triple angle?
Latter
Okay
i got 8sin(x)cos^3(x) - 6sin(x)cos(x) - 4cos^2(x) + 3 = 0
But i dont know what how exactly should i factor this
Ahem
Take 2sin(x) cos(x) common
Ok
(Please ping when responding)
Hm
By the way, are this identity and triple angle identities popular? Should i learn them by heart?
Because i hardly ever use them, however this equation used both
Eh i mean the derivation is easy enough jusf derive it
I dont know how to derive it
Look it up its easy enough
Okay
I have forgotten limits
Why is the limit as x approaches 0 36?
\frac{\left(\sin\left(6x\right)\right)^{2}}{x^{2}}
My first thought is infinity since {x^{2}} is in the denominator
$\lim_{x \to 0} \frac{\sin (x)}{x} = 1$
Transparent Elemental
How is that proved?
you can google the proof
I mean the equation you gave me
guy just tell me one thing
does product rule for integration exist or nah
cuz my physics teacher told me there aint nothing like tha
but a book i follow has a rule formula named "integration by parts"
and google says i exists too
product rule would say something about the integral of a product of two functions
which you can't say anything about
so what do u mean??
that's what product rule for derivatives does
it relates derivative of a product to derivatives of something simpler
oh
i somewhat get it somewhat dont ( im new to calculus thats why lol)
so like u get the answer but it isnt exactly what you would get
could someone explain thsi for me
i dont get what i got wrong
its coming to zero from the right side
and i dont get how it works cuz there are holes
The limit looks at behavior near the point rather than the point itself
The graph is approaching 0 from both sides as x -> 0
As far as the graph, there is a hole at (0,0) they didn't draw well or at least it's hard for me to see
But otherwise it wouldn't be a function
How can I apply taylor series to a limit?
For example, I wanna solve this limit when x tends to 0 of sin (x) divided by x using Taylor series.
$\lim_{x \to 0} \frac{\sin (x)}{x} = 1$
Machholz
This will go to #calculus
But you just need to substitute the sin(x) with its power series at 0 and then divide it by x. Since the series converges uniformly then you can interchange limit with infinite sum and thats it
Thanks a lot!
Could some explain the difference between chain rule and product rule?
I'm kinda stuck lol
Chain rule is for differentiating functions of the form f(g(x)) while the product rule is for f(x)g(x)
Also this belongs in #calculus
Hey, so I wanted to learn calculus and downloaded the book Calculus: Early Transcendentals by James Stewart, and realized that I have huge gaps in the knowledge required from the diagnostic test.
I am currently 12 months in my 14 month army service in Cyprus, and things are starting to get easier. Every 6 hours, I have a 3 hour number where I basically just sit on a desk and write the credentials of anyone that takes out our puts in a gun. That is a great time to study, and I am currently just wasting that time on my phone.
Can you recommend a good precalculus book that will cover everything extensively? If I can't finish it during the next two months, I am prepared to put in the work in University as well.
Thanks!
What about this one?
https://www.opentextbookstore.com/precalc/
Hello. This is 9th grade math (functions). I don't know how to do the exercise in the middle. It's in spanish so I'll try to translate it:
"According to the following conditions for the functions k(x) and t(x)
k(2)=4, k(4)=8, k(6)=2, k(8)=6
t(2)=4, t(4)=8, t(6)=8, t(8)=4
Determine.
a. (kot)(2)=
b. (tok)(2)=
c. (kot)(6)=
d. (kot)(4)=
e. (tok)(8)=
f. (tok)(6)="
Please help.
Hello, i don't exactly know what kind of operator "o" is but I'll give you a general idea of what you have to do in these cases.
A:
(k o t)(2) = k(2) o t(2) = 4 o 4
B:
(t o k)(2) = t(2) o k(2) = 4 o 4
"o" is the function composition
then you can apply that (f o g)(x) = f(g(x))
I tried doing that, but every result ends up being 8 except 2.
I tried k(t(2)) = k(4)=8.
I also tried k(8)= 8(8)=64
or 2(2)(2)=4(2)=8
(f o g) is (k o t), I know that much
but the (2) instead of (x) messes me up
well it has to be that way, the 8s might be only coincidence
no problem
whats special about precalc
Idk js never done it
what do u know about it
everything is hard when you've never done it before
especially in mathematics
don't be too discouraged!
practice makes perfect, as they say 
trig, composite and inverse functions, rational functions, logarithms and exponentials
I'm not American and only American people call it precalc
That just algebra in my country
factor and remainder theorems, polynomial long division
Depending on your depiction of "america". It's not just the US, Canada has it too
indeed, there's no single definition of precalc
technically all countries have material that is covered before calculus
but Ontario calls it advanced functions
BC calls it precalculus I think
MB calls it precalculus, yep
ahhhh right yeah just not Ontario fair enough
and whatever the frick Alberta calls it I'm not sure
Who knows
Even calculus courses go by different names in different places
exactly
We did so much in precalc
Wait, calculus has different name?
Anyway, yeah. Precalc by the cirriculum I had was teaching exponentials, logarithms, trig, rational functions, and inverse functions
Okay to be fair, my analogy was actually incorrect, lol
It's because calc courses go by different names, but never mind, that has nothing to do with actual alternative math names
I often say calc 1/2/3, just because generally speaking, even if places do things a bit differently, most people are able to distinguish between what content goes inside of those
I guess saying differential calc, integral calc, and multivariable calc is even better though
yes, like different unis call it differently
there's not just single-variable calculus but also multivariable
Not like I really know much about calc yet. I only recently finished calc 1, and have just brushed the surface of calc 2, lol
Make sense
I also often call calc 1, 2, 3 but my university have different courses on them
But calc 1, 2, 3 look universal enough so everyone know what in it
Calc 2 is the only one at my university that goes by that name
Calc 1 goes by "Introduction to Calculus", which is honestly a pretty fair name. And calc 3 goes by "Multivariable Calculus".
Hi
Can anyone help me with it
I tried applying difference of cubes formula and i also tried solving the system of equations but neither helped me
Recall that $$a^3-b^3=(a-b)(a^2+ab+b^2)$$
Civil Service Pigeon
I did it
thats the difference of cbes formula lol
you can replace a with b + 9 then
^
you can do that or reduce it to a system in (a+b) and ab
Using the fact that:
- ||a^2 + b^2 = (a+b)^2 - 2ab||
- ||(a-b)^2 = (a+b)^2 - 4ab||
(Note that a and b are complex numbers that aren't particularly nice to work with)
reduce it to a system in (a+b) and ab
so they probably intended you to do this
especially b/c they explicitly ask for a product
I dont understand it
What do you mean by reduce it to a system in a + b
I should've said "rewrite a^3 - b^3 in terms of a+b and ab" tbh
But i dont have a^3 + b^3. Instead i have a^3 - b^3
Typo, the idea still holds.
don't divide 27
you should have 9(a^2+ab+b^2) = 27
? they said "27 by it" not "it by 27"
And replace a-b with 9
And divided 27 by it
wait do you mean divide 9 by 27>
it's clear "it" refers to 9
yeah but that's a lot of extra work
you're better off just doing this
b/c this
using this
oh yeh tru
i think -26
is that pi in the second line?
no it's x which is ab
a simple variable
bird $$3+3*3$$
Mark
wow nice formatting
these r just homework questions I cannot figureo ut
would love some help
also how is this the wrong slope?
what do you need help with?
you can rewrite the square root(f(x)) as [f(x)]^(1/2)
and then you can use the chain rule
what don't you understand?
how to differentiate it?
yes
you know how sqrt(x) = x^(1/2) ?
yes
so like sqrt(x+2y) = (x+2y)^(1/2)
right
and sqrt(3xy) = (3xy)^1/2
and then you can use chain rule right?
And no it’s not correct
Why would something be more than -4 and less than 4
absolute values cannot be negative
what you have there is satisfied by the entire real line
The first message yes but not the second message
Could somebody clear this up for me here? I dont get why my answer is wrong
I used system of equations to get my quadratic equation
I used points (1,6) and (2,1) because it seemed easier
So like:
a(1)^2 + b(1) + ~~c ~~= 6 --> a + b = 6
a(2)^2 + b(2) + c = 1 --> 4a + 2b = 1
c's cancel out
Multiply (a + b = 6) by 4 to cancel out one of the terms
4a + 2b = 1
-- (4a + 4b = 24)
-2b = -23
b = 11.5
Plug b into a + b = 6
a + 11.5 = 6
a = -5.5
Plug a & b into quadratic equation:
-5.5x^2 + 11.5x + c = y
Use one of the points to get c:
-5.5(1)^2 + 11.5(1) + c = 6
-5.5 + 11.5 + c = 6
c + 6 = 6
c = 0
Equation is y = -5.5x^2 + 11.5x
i really dont get it
@winter comet I need you pls
you need three points to find the unique quadratic passing through these points
so a + b = 6 is already wrong, the c doesn't go anywhere
you have a + b + c = 6 and 4a + 2b + c = 1
if you subtract both equations, you get -3a - b = 5
you need another equation like with the point (6, -99), so 36a + 6b + c = -99
see how you go from there
Hi, If we know a function isnt polynomial, exponential or logistical. Can we safely say its linear? The derivative of the function is always an integer ≥ 0
And f is also an integer
No
If the derivative of the function is always >= 0 then we know it is an increasing function
still the same
But = 0 isnt increasing
If the function is linear then its derivative is always equal to a constant
increasing doesn't mean strictly increasing
increasing can be 0 but strictly increasing is always > 0
By linear, i mean when the scale at which this function is viewed at, is huge
So these scenarios where f'=0 seem to disappear
And f smooths out
Do you mean when you zoom in on a function it will look like a straight line?
When you zoom out
Linear is also polynomial
When you zoom in, it looks like increasing linear at some ranges, then constant 0 at some too
Ik, but by linear i mean its a line, not parabolas or similar
when you zoom out large enough, a function might look like a straight line, but it doesn't mean it is linear
kind of like an illusion
No
Like, if we are given properties of this function. Can we prove that it will assume linearity as its domain increases
I have no idea what you’re expressing
What is “f is also an integer”?
...
Does this count as spam?
Think so
You know like how pi(x) is approximated with logs
I think he means for example, when you graph a function on a graphing calculator, and you zoom out large enough then the graph looks like a straight line

Nah I don’t even understand the first thing he said
What “and f is always an integer”
if f(x) is always an integer, then f'(x) will be undefined
☠️
?
Your domain is still in real number right?
No decimals
like x = 0, 1, 2, 3,....?
f(x), f'(x) = 0,1,2,3,...
I mean $x \in \mathbb{R}$ or $x \in \mathbb{N}$ ?
NKH
mainly N_0
But we can accept and approximate the output of decimals too
But as mentioned this is just an approximation
I am confused about what you are trying to do. But if you want to prove that a function f(x) is linear like you said then you need to show that an increment of x at which the function is approximately linear?
I dont understand your statement, can you elaborate thx
like: at every $x + \Delta x$ then $f'(x + \Delta x)$ is approximately equal?
NKH
you need to find: $\Delta x$
NKH
Thats true for x ≤ 2000. But i dont know how to prove it for the other values
Then just set that as a condition
Condition for what
So if x <= 2000, f'(x) is approximately equal?
Yea
Is this a problem in your school? I am very confused
Nah, its just something am working on independently
I wanna know if there’s a calculator that can solve all types of calculus problems for high school
Btw its not typical highschool calculus, alittle more advanced
Wolfram?
If you want a handheld calculator, you can try Texas calculator
It also has a computer algebra system like Wolfram
Can it derive, integrate, find the bounded area and so?
Also these are examples of the problems I have
Iam not se well-educated about the names and so sorry😭
Yes
You can try wolfram first
Any tutorial video?
Tutorial for what?
How it solves such equations as shown
i've got one
but it's in hindi
Its alr ijust wanna see how it does things
its also 5 hours long , but what you are looking for is explained very clearly in it \
✨ IIT JEE Plus Subscription @5,499: https://unacademy.com/goal/-/TMUVD/subscribe?plan_type=plus&referral_code=PJLIVEJEE Complete Notes and Lectures – Atoms- ...
i can solve it but , im doing vectors and 3d rn
Imma watch what i need and get back to you, thanks man!
if im doing binomial expansion and the first variable has a coefficient, how do i do it
i tried to find some videos online explaining it
but nothing really shows up
any recommended vids??
you apply basic exponent laws
raise the coefficient to the appropriate powers as well
ex $(2x+1)^2=(2x)^2+2(2x)(1)+1^2=4x^2+4x+1$
elrichardo1337
more explicitly, $(ab)^x=a^x\cdot b^x$
elrichardo1337
is there a faster method to do this when you have a large exponent
I have to get the power to the ten
do i have to just do it by hand?
Binomial theorem
yeah, like i mean
in the binomial theorem
how do i plug in the 2x for example
like where does the 2 go
in front of the "a" where a is to the power of n - k
No
The 2 should also be raised to the power
You can imagine replacing 2x with another variable like u, and then substituting 2x back in once you've applied the binomial theorem
so i would go (u + b)^10, apply the theorem, get the final answer, and resubsitute "u" and 2x?
Yes
<@&268886789983436800>
hello guys , i am stuck with this problem , so , someone can help me please it 's an EMERGENCY !! show that (n+1)*3-n is equal to the sum from 0 to n of 3-n pleaseeeeee 😦
Pretty sure you could change this into an arithmetic sequence
Where a_n = 2, 1, 0, -1 ..., -(n-3)
So d = -1
And the sum S_n = (2a_1 + dn - d)*n/2
Then you could maybe continue from here and try forming equations and manipulating stuff
(5n - n²)/2 = (n+1)(a_n)
(5n - n²)/2 = (n+1)(a_1 + dn - d)
(5n - n²)/2 = (n+1)(2 - n + 1)
(5n - n²)/2 = (n+1)(3 - n)
(5n - n²)/2 = 3n + 3 - n² - n
5n - n² = (3 - n² + 2n) * 2
5n - n² = 4n - 2n² + 6
Might have done something wrong, but there exists some values of n where LHS ≠ RHS. Therefore the two sum formulars arent the same
wait, it's all conics?
@fickle cedar
Deleted
confused if this is wrong because ive checked on my calculator and im pretty sure the answer is b
wolfram alpha agrees with you
= ?
I’m pretty sure the answer is b
hmm b and c are equal
this is just a poorly made question
they want the expression obtained via half angle (ignoring that it can be simplified to the form shown in answer choice b)
i think their "intended" answer is c then
pls help me with this question . ([] means greatest integer function)
this means that x + 1/3 has to round down to 2, but x + 1/2 has to round up to 3
So the endpoints are x = 2 + 1/2 and x = 2 + 2/3
but it doesn't include 2 + 2/3, cause you get 3 + 3 = 6 instead of 5
how many values of x did you get?
8
so from 2 + 24/48 to 2 + 32/48, but not including 2 + 32/48
so 32 - 24 = 8
how did you get those numbers?
this
x + 1/2 is always greater than x + 1/3
so [x + 1/2] has to be 3 and so [x + 1/2] has to be 2
that's the only possible way to make 5
that's impossible
[x + 1/2] and [x + 1/3] can only be 1 apart as (1/2 - 1/3) < 1
1 part meaning?
[x - 1/2] - [x + 1/3] can only be 0 or 1
but why??
from the definition of the floor function
Like keep trying different values of x such as x = 1/6, 1/2, 1/3, 2/3 if you're not convinced
cause you're rounding down, so if you have x + 1/2 and you add 1/3 - 1/2 = 1/6 to it
then you can cross a number, so x + 1/2 can round down to 2 but x + 1/3 can round down to 3
you can't have that x + 1/2 rounds down to 2 but x + 1/3 rounds down to 4
i think i need to learn some maths

Why do we take infinity as 1/0 in limits
Idk if I’m understanding what you’re asking but because 0 on the bottom would make it undefined, there is a asymptote at that spot
I take 2/0
We don’t really take infinity as 1/0
Hello, guys
I need help
cos (10^x) = 0
My answer is x = log(pi/2 + pi*k), k is an integer
But
I doubt that k can be any integer. Because if it's a negative integer, then the argument of the logarithm is also negative
But it's beyond a log domain
So
Should i say that the answer is x = log(pi/2 + pi*k), but k is a positive integer including 0?
sure, so you could say $x = \log(\frac \pi 2 + k\pi)$ for $k \in \mathbb{Z}_{\geq 0}$
Pseudonium
But photomath says the opposite
It says this is right
Is it just x = log(pi/2 + k*pi)?
Where k is an integer
So is it the correct answer?
technically correct but it's redundant
But if k is negative than it's beyond the logarithm domain
they've split the list up as (pi/2, 5pi/2, 9pi/2....) and (3pi/2, 7pi/2, 11pi/2....)
I mean they say that k is any integrr including negative ones
yeah so you could have a complex logarithm
if you have a complex logarithm then yeah those solutions aren't correct, you would need to be adding on multiples of 2pi i / ln(10) as well
yeah, complex variable will solve the problem
so yeah PhotoMaths doesn't understand maths logic
Oftentimes, math software will give you solutions in complex domain
I dont know what are complex logarithms, sorry, so what's the final answer without those complex logarithms
value of k that makes log non-negative
Okay, thanks. But are those complex logs learnt in high school?
I don't think so, high school just gives you an introduction to complex number
You meant log's argument?
Yeah, if you want you can solve $\frac{\pi}{2} + k\pi \geq 0$
Closer
to find value of k
this is just $k \geq 0$ anyway
Pseudonium
cause k is an integer
Okay, thanks, i just want to clarify everything so that i have a solid understanding of it
mhm
And i am struggling with this equation
I tried using logs on both sides
But i think that after that and applying square of sum formula i only complicated this
I think you can try applying ln on both sides of an equation
so you have this: $ln(3^{\sqrt{10-\sqrt{x}}}) = \frac{3}{2} ln(10-\sqrt{x})$
help
Closer
I still cannot figure out what to do next
Maybe i should let 10-√x be t
Why
From that I can make it to this: $\frac{2}{3}ln(3) = \frac{ln(10-\sqrt{x})}{ln(e^{{\sqrt{10-\sqrt{x}}}})}$
Closer
I don't know how to simplify it further 
uh i dont have a perfect proof but here we go
$\frac{2}{3}ln(3) = \frac{2*ln(\sqrt{10-\sqrt{x}}}{\sqrt{10-\sqrt{x}}}$
Ender Doesn't Mind
now we can divide by 2
and we see that both are of form ln(t)/t
hence by simple comparison
sqrt(10-sqrt(x)) = 3
ie x = 1
but there is probably a much more formal proof
Thanks
By the way why ln x^c = c * ln |x| when c is even?
Is it because √a^2 = |a|?
But any even root
wdym?
when c is even it allows x to be negative however if we take it out it will be ln(negative number) which is not allowed hence we take it as ln|x|
yea pretty much
But when c is odd, we left x as x, but not as |x|, because x^c (c is odd) cannot be negative in logarithm by default?
I mean is it a reason why this rule doesnt apply to c when it's odd
if c is odd and x is negative then it isnt defined anyways
Okay, i understand it
Can anyone help with it?
I need to factor it, but ln |x| and ln x are different, right?
Note that you can't have x < 0 however, cause ln x would be undefined
hoi
so all your solutions must have x >= 0 cause of the RHS only being defined for x >=0
So what should be done next?
But i dont understand why we can remove absolute value
the right hand side is (ln x)^3
i still dont understand why rhs matters
cause ln x is not defined for when x is negative
so (ln x)^3 wouldn't be defined either
So you're saying that x cannot be negative by default since we have this RHS?
yes
So there is no need to use abs value
yeah so if there are any solutions, they must all satisfy x >= 0
and so you can drop the | |
But if it was 4ln |x| = 0, we wouldn't be allowed to drop the abs value?
Cause x can be any number
yeah that's correct
you'd be better off doing ln(x^4) = 0 implies ln(x^4) = ln(1) and then ln is 1-to-1
Okay, thanks, i got it
np
Or you can set: $4ln(x) - ln(x)^3 = 0 (x \geq 0)$ so you don't have to deal with absolute shi*t
Closer
Absolute is really annoying
you have to provide a reason why you can drop the absolute value sign though
you can't just drop it randomly
I don't drop it randomly, I have provided a condition so it is still valid
I saw this a lot in textbook, though
oh shit didn't read x >= 0, sorry
No problem.
But setting conditions like this will not give you a general solution
I mean it gives you all solutions in the real numbers so
In this problem, yes. But I am pretty sure there are a lot of problems where setting conditions for absolute value like this will not give you general solution even when it is in real number but it makes your life easier 😂
oh true yeah splitting into cases then
Yea, that is why absolute value is really annoying
please why is it that when you use the u-substitution in an integral like this:
Int(1/x^2(root of x^2-(9))
It doesn't work??
because it doesn't? (at least w/ the substitutions you've prob tried)
if you substitute u = x^2 or x^2 - 9
du = 2x dx
you don't have a factor of x
hence it doesn't work
ohh yeahhhh
It's either using à trig fxn or factorisation
Like setting x=asectheta
Or just factor out .
Btw, questions like this belong in #calculus, not #precalculus
Yeah my first instinct is trig sub
$\sin x=a, \sin y=2a, \cos x=3b, \cos y=2b$
Civil Service Pigeon
Now, consider what identity relate sin and cos
You should think of ||the Pythagorean theorem||
How did you figure this out?
That's just the ratios
Right, you don't need abs, strength is more important these fitness freaks making abs overrated
Which average rate of change is greater -0.04 or -0.4?
-0.04
yeah I'm sure that generally -0.04 is greater but when a question says which has greater rate of change wouldn't you say -0.4 because it changes the most?
Oh,yes yes my bad.
Ok thank you
Can someone help me with these
Have you tried all these questions at least once?
No i dont understand the topic that well
So i kind of skipped them
You should then first get a grasp on the graphs of quadratic functions
Are you an 11th grader?
10th
for the first one
remember k is the y intercept
so find the y intercept of -x^2+3x
and use that for the others
<@&268886789983436800>
I'm just joking..
Hurb
sorry alr
lets not please, thanks
oh ok
not exactly a good advice but
It's valid only if 1/sqrt(6-3x) is defined
sorry
a fraction is defined when the denominator is not zero so sqrt(6-3x) cannot be zero thus 6-3x cannot be zero
and the square root inside is only defined when 6-3x is non-negative
this leaves you to solve for values where 6-3x is positive
basically you can see that $\sqrt{6-3x}>0$, you can say that $6-3x>0$, so $6>3x$, then $2>x$, if you srebt sure its absolure or not, just try a number where one is correct and the other isnt, so for example -3, you can see that the value is valid
Skill_Issue
i think they are wrong
Yes
No that's correct
,w 1/sqrt(6 - 3x) Maclaurin series
Not true, a function's power series can diverge even if the function itself exists
This is calculus @north nebula
And this question is?
Your question is calculus
Oh wait I just saw the expansion oops
WA won't tell me the radius of convergence goddamjt
With this question about the conversion, the general rule is that x< absolute (1) right?
But is there an expansion where x doesn't have to be in that range?
It feels a bit useless having an expansion that is only valid for such a small amount of x values right?
the expansion doesn't converge to the function elsewhere
that's the largest possible domain that it converges
But if we use for example (1+2x)^-1
Then we would use this formula if im not mistaken
We would have to say The absolute value of 2X is < 1, but couldn't there be greater values for x than 1/2 that would still yield answers?
would the answer we get from above formula be plain wrong if x were to be greater than 1/2
you can just google whether the series for (1+x)^{-1} converges for x >= 1
different series converge in different ranges
you can't just always say |x| < 1
I have this alpha mathematics book, I hope im understanding this right
so i think if there is (1 + (X) )^-1 then whatever is in place of X, that sould be < 1
How do I differentiate
X^2ln(lnX)
Can anyone just me me what to do with the ln(lnX) part?
I am very confused
the chain rule
yes...
for ln(ln(x))?
No
or for x^2 ln(ln(x))
Yes
yes you have to use the product rule for the entire thing
but you asked "can someone just tell me what to do with the ln(ln(x)) part" and you have to use the chain rule to differentiate that
Ahh so you were talking about that part
yeah
i mean you will eventually differentiate ln(ln(x)) and use it in the formula for the product rule
what is the problem
you did sum wrong lol
But how can I multiply 2x and lnX?
why X?
you don't, and also its not correct
So I keep it as it is?
Btw it's lnx
Not lnX
That was my keyboard auto correcting me
d/dx x^2 ln(ln(x)) = x^2 * d/dx [ln(ln(x)))] + 2x * ln(ln(x)) by the product rule
right
Yes
Ahhhh right
and then you can plug that into here
That makes sense but didn't make sense at first
So that's where I made the mistake ig
I did
A d/dx B + B d/dx A
But I took A as x^2ln
Yea
ln(ln(x)) is like f(g(x))
and xf(g(x)) is not xf * g(x) like its not multiplied
its a function of
doesnt really maek sense to do :l
Am just doing the hard stuff first then imma start with the easy stuff
Oh right
Another problem....
Yeah it did come as x/lnx
ok
wdym
oh i meant
x^2 * 1/ln(x) is wrong, its actually x^2 * 1/ xln(x) which simplifies to x/ln(x)
But why though?
the derivative of ln(ln(x)) is 1/ln(x) * d/dx [ln(x)] = 1/ln(x) * 1/x = 1/xln(x)
chain rule
Ehhhhhh
you just have to use the chain rule :l
Can somebody help me explain the symmetry here
x^3 - 4 also looks symmetric but also x^4 - 4 when i plug it into desmos
Whats the difference here
x^4 - 4 is not symmetric
could someone explain to me how this equation matches up with the graph e and not graph d?
why do you think it should be d
asymptotes are the same for botg
yeah so like how can i tell the answer 😭
sub in a few x coods for points
to see which section the curves will be in
e.g for something between the asymptotes
what happens when x=3
Hi guys, I'm having trouble with arithmetic, does anyone have a book to recommend?
both sides of what?
Positive and negative on the x axis
wdym?
Ok,
So like on a quartic or a quadratic it goes to infinity for either -infinity and infinity on the x axis
what is x^4 - 4 symmetric about
what is y = x^2 symmetric about?
????
why the question marks?
Because I dont know man
If you could explain that'll be great
If not i can just ask someone else
without looking it up (cause if u dont know i can explain it better) what does it mean for something to be symmetric
Equal on both sides evenly
in terms of shapes and geometry, more specifically
Equal in size??
Yes
two shapes could look very differant and equal in area btw
ok so
sorry my parents kept bothering me
a shape/curve/graph is symmetric about a particular point/line (etc.) if for every point on that graph, the reflection of that point about the point/line of symmetry yields an image that also lies on the graph
try to understand this
@white rapids
this u should rlly know
its called the axis of symmetry of the parabola
heres a quick sketch of this
Right
So why cant a quartic function be symmetric even though at the same x value, its 2 of the same y values
what is y = x^4 - 4 symmetric about, if anything?
Lets say
and why
For x^4 - 4, for 1.25 and it's reflected x value, and we plug it into the function
Both the x value and its reflected x value, are the same y value
Both points are equidistant from the axis of symmetry
It doesnt have to be x^4 - 4 but literally any transfomation or shifts it has
wdym?
what is x^4 - 4 symmetric about?
Because this still applies
that doesnt answer my question what is it symmetric about
For any reflected x value, it'll be the same y value
It has the same reflected image whether its going x negative or positive infinity
that still doesnt answer the question
what is x^4 - 4 symmetric about
@white rapids
u r never answering the question i dont know why
what line/point/shape is the graph of x^4 - 4 symmetric about
@winter comet
can u answer pls?
yo
Im not sure if im misinterpreting this
its symmetric about x = 0
yes i wanted to get them to figure that out
they wouldnt answer
Axis of symmetry i thought i said that
ok so now we have figured one thing the graph is symmetric about
but why is x^4 - 4 not symmetric about (0, -4)
i meant what in particular
symmetric about a point i'm pretty sure means the same distance, 180 degrees away
a reflection
this should fit
except about a point instead of a line but yeh...
@white rapids
thats why the odd function reflects about the point and the even function doesn't
an odd function is specifically defined to mean symmetric about the origin i.e. a point
but im pretty sure u have heard of lines of symmetry in a square for example
How do you get 180 degrees
Do I gotta look at the z axis or something
just by definition of "reflecting over a point
nah wut
this is all just 2 dimensional
@white rapids
I still dont understand
why
alr uh
what dont u get
Are we looking at x = 0 to know whether it determines
no
no
otherwise x^4 - 4 would be correct
it says a point not a line
why is x^4 - 4 not symmetric about (0, -4) @white rapids and not vicious viper pls answer this
"Because"
-greatest answer