#help-36
1 messages · Page 182 of 1
GIF is the common bracket for Logarithms, it doesn't matter much in calculus (at least integration)
Oh is that so?
Eh, or I might be wrong, but it won't affect our question
I remember seeing some questions with GIF, so it does matter, but not in this particular question
f(a + b - x) can be written as log(2 + x) - log(2 - x)
Then integrate using parts?
Nope
A faster method
f(x) was log(2 - x) - log(2 + x)
-f(x) would be log(2 + x) - log(2 - x)
So add both
And that is f(-x)
(Or f(a + b - x))
Now what do we call a function where f(-x) = -f(x)
Odd
And the integration of an odd function is?
Yup
Oh
And here a is 1
In such cases, where the lower limit is just the negative of the upper limit, we always first check if f(-x) = -f(x)

[x] DOES make a difference
I guess we do, because it shouldn't change the fact that it is an odd function, at least in this question, I'm not sure in general
Yup I realised that, I added a correction later
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The function isn't defined for x>0, so it isn't odd
e.g. at x=1, log(floor((2-x)/(2+x)))=log(floor(1/3))=log(0) which is undefined
@tranquil pine You have to consider cases based on how the function is defined
Oh
@tranquil pine Has your question been resolved?
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Does this proof look good?
do you mean disprove
yeah sorry
oh if im disproving
would it be better to prove the negation
not really sure what that would be of this set though
Don't you just need a counterexample?
yeah thats true, is the counter example I proposed correct?
You didn't though
oh I didnt?
I thought I took an (a,b) in the left hand side
and showed it wasnt in the right hand side
maybe im misunderstanding what counter example means
A counterexample would be stating explicitly four sets (A_1, A_2, B_1, B_2) for which the equality is false
ohh ok
There may be some slack in the definition of a counterexample but to me it's with concrete values
You would also try to make them as simple as possible, while it's not mandatory
Ok i'll try to constrcut a counter example
@lapis wedge Has your question been resolved?
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,rccw
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
Apologies for absence
3rd one and don't know how to begin
It's multiple correct
IVT?
High school?
Btw I'm an 11th grade student
Yeah ok so nvm
This just needs Rolles doesn't it
⁉️
If a continuous function changes sign it is zero at a point in between
High school level
I recall having done this during my JEE prep
yeah you should have been taught rolles
Hence me bringing it up
unless calculus hasnt started at all
I'm high schooler and I already know rolles lol
but then why are you advance
I'm just at the quadratic equations
In my country they don't teach calc like uni
rolles is just general shit formalised in a statement so people doesnt need to think it from scracth
yeah it's kinda obvious when you look at it
Yeah it's easy to understand i agree
This looks like they wanted to type (x-e)(x-pi) in the denominaror on the right fraction
Unlikely
Then when you multiply by (x-e)(x-pi) its a quadratic
They have π + e in the options
yeah there are a few jee question in the chapter quadratic equation which can be done with rolles theorem quickly , so i suggest you can mark this question , do it the conventional method and come back in like 12th 2nd month
So they definitely wanted it to be x - π - e
Oh I am stupid
But i should develop my problem solving even without it shouldnt I
its just location of roots simply , but very lenghty otherwise , you also need to understand how you use the tools you have given
Hmm
Probably we aren't even given its solution in it's pdf
quadratic equation can be solved using the completing the square method too , but do we use it generally?
middle term split does the trick most casses and sometimes we have to use quadratic formula
Shall I call someone
A good helper
By pinning her🫣
you know na how you can solve using this?
That will truly look as ugly as hell ig
chapter name
Not all problems will have pretty solutions
Especially when you don't have the necessary tools
is location of root one of its topic, this is the question from that topic.
And the numbers are ugly
Sometimes you need to get your hands dirty
Yes
Fr😭
Also I do not appreciate you calling the three people trying to help you "bad helpers"
hence i suggested to mark and move on
No, solve it using what you have now and come back later
yeah thats fair too
Umm i didn't mean that
Should still understand how to solve it on the base level
it was implied
Anyway go do this
Oh universe lend me ur energy
I'm gonna solve this ugly
(I was hoping he'd make that realisation himself)
yeah true fair mb
I was thinking but,.....
Were u IITian
Nah, I got the JEE trauma as inheritance
Btw how do ppl become helper here?
It's a role you self assign isn't it
Idk
Then ig ull get that soon
hes talking about the green role
Btw I guess like how helpers spent their time here they might be paid but no way
its auto assigned to the person who is actively helping ig
Ehhh no maths research leaves you with a lot of downtime
nah most people here are highschool/ college math students , so yeah free time pass
At least if you manage your time properly
Anyway, stop talking and go get your hands dirty
That equation is literally becoming more than like 2 lines
Collect the coefficients
Btw why is e so used why is it a natural no. Like one that is recurring
The original discovery of e was when studying compound interest
Dirty equation
But the one you might appreciate the most is the limit formulation
Oh great
CI that i studied in 8th grade
e is the limit of (1+1/n)^n as n approaches infinity
A lot of graduates
higher levels of that
Ik
yeah thats fair , **mostly **graduates are more active in the higher chanels or if a higher question is asked in the help chanel
which is lwk fair
Yeah...
Unfortunately very few people here are asking what I'm working on so I'm stuck with JEE trauma
grinding help channel and you will have that role
How many hrs spent?😜
bro do your question , talk in #discussion if you have smthing else
Sry
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Xavier's specimen
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6th one
I'm stuck in between
Show your work, and if possible, explain where you are stuck.
do that, then i'll share my idea if applicable.
your work looks kinda hard to read ngl
can you rewrite all this but calligraphic please
Lemme Redox it
I find the problem statement really funny:
...then a value which is greater than |n+m| is
...I'd just choose the highest value out of spite >:D
It's multiple correct 😑
ah, again it is weirdly written as if they are asking for one
I ain't a fool neither are they
Here it is Ann
ok let's see
so D ≥ 0 yep
but i think you set up the discriminant incorrectly
$\frac{3x^2+mx+n}{x^2+1}=y \to yx^2 + y = 3x^2 + mx + n \to (y-3)x^2 + mx + (n-y) = 0$, which gives $a=y-3$, $b=m$ and $c=n-y$.
Ann
so either you did some funny business in your head or you messed it up
or both! who knows.
but i would have expected $$m^2 - 4(y-3)(n-y) \geq 0$$
Ann
Ummm, sure?
It's just I solved it😓
No one understands me😭
well you may have solved it but then you didn't communicate it properly.
i for sure was confused at what you idd.
did*
also i just realized the x^2 coeff in my thing should be 3-y and not y-3, oops.
and "not communicated properly" qualifies as funny business, btw.
Yeah I was thinking the same
But I was not so courageous to oppose an post-graduate😅
oh come on
Well that doesn't matter
Let's go ahead
just because i have a master's degree does not make me a goddess who is never to be doubted or crossed
anyway, $$m^2 - 4(3-y)(n-y) \geq 0$$
Ann
Yepp next
the solution set of this ineq should be [-4, 3] but for now we should only keep that in the back of our mind.
and instead simplify this inequality. carefully, step by step, and without funny business.
Hdyk
I did and it is right
original question says the range of $\frac{3x^2+mx+n}{x^2+1}$ should be $[-4,3]$. the equation $\frac{3x^2+mx+n}{x^2+1}=y$ should have solutions for $x$ precisely when $y \in [-4,3]$ (no more, no less).
Ann
and what are your m and n
if you solved the question then why are you even here
U mean that I have to compare both equations?
... ok, we are definitely not understanding each other
wtf did you mean when you said "i did and it is right"
I meant that i simplified that equation 😅
inequality*
As u say
so whats this then, is that the simplified version?
Yepp
ok yeah i retraced your steps and you didnt fuck up
now you need this quadratic in y to be equal to 4(y+4)(y-3).
(for all y)
so yes you compare.
U r belief that i will f up is absolutely absolute
Like Why?
I did these just following my intuition
my gripe was that your work was mostly unwritten/mental which means unverifiable to external parties (everyone except you)
Leave it
idrk how best to explain it other than "these both are quadratic inequalities so the one with m and n has to have roots exactly where the other one does"
Why whats the relation😭
Oh
Actually both are same
Both represents y
But why less than or equal to 0
I'm f up
Isn't it the range
Why would I get it as roots
Yes
It's the all values of y
you've written down an inequality whose solution set is that same interval
Why how?
ie you have passed from a "find the range of this function" exercise to a "solve this inequality" exercise...
cause of your discriminant ≥ 0 thing??
Oh yeah that should be greater than 0
Bcoz y does have roots
lemme try to illustrate the logic here
Sure 🙏
your solution feels you are solving it like a set algorithm i dont see a thought process here
you've got 3 statements here
and the logic that underpins solving this question is the logical equivalences between these statements
this requires higher-level awareness than simply the ability to solve an inequality
Wait
I said that it was my intuition
vibe mathing 
Yepp
Truly i was doing that
mmmmmmmmmmmmmmmmmmmmmmm no good.
It's range why is it related with that
consider the function f(x)
if i write x>0 ,
can you tell me whats the domain
Okay did you understand the first part of what Ann did
there are 3 equivalences here which i've conveniently color-coded
(two of them look black to me)
"known from theory" is green.
Understood
Colour blindness kicking in
my aim is for mathemystic to:
- understand the red equivalence, AND recognize that it is question data
- understand the green equivalence, AND recognize that it is a manifestation of theory
- understand the black equivalence, AND recognize it follows from the other two, AND recognize that it is the path forward
My, my, thank u guys for doing this so much for me🥹
I think I've read the question well
Do you recognise any of those
Idk
I just know that u made me understand despite of colours
Ty
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Problem Statement: Given an array and a sum k, we need to print the length of the longest subarray that sums to k. how do i start with this? i know i can check which elements equal to the sum given, but how exactly do i keep track of the longest sub-array?
one thing i can think of is:
i keep track of all the sub-arrays whose sum equal k
and then check which one has the maximum number of elements
but i think that would result in a lot of memory wastage
plus would not be convenient
Are you familiar with dynamic programming
no, not yet
i am not really sure how i am going to start with it, but i provided which direction my mind is going in
No I meant if this is for a course, what types of algortihms have you done so far
it is not for a course. i have just started learning arrays
i am not following any course
I see
If you haven't done dynamic programming, all you really have for this is brute force
not sure what exactly do you mean by that
Dynamic programming is a type of algorithm essentially
Until you learn that, I don't think you can solve this in any way that isn't to just check all subarrays
(which is what your approach was, I don't think you currently have the tools to do better)
well if you're not concerned about speed, you can get all subarrays, check which of those sum to k and then return the longest of those 
That's already her approach
but would that not result in a lot of memory/cost wastage?
It would yes
But until you have some better tools it is the best you can do
Look up dynamic programming if you wanna explore that
what exactly does it come after? i really want to go step-by-step
I have a solution
I'm not sure, I studied algorithms very out of order lol
That's quite the jump in difficulty
i want to build-up my logic thinking
@plucky rover I don't see how dynamic programming helps here
Wait hold on have I been saying dp instead of hashing
I don't see how hashing helps here
Hashing definitely helps here
i know a little about hashing, in theory
Ok here’s the thing, assume your array has n Numbers. Test all n arrays (There’s 1), then test all n-1 arrays (There’s n), etc.
Now think of the kind of test you wanna include
Is that really your solution?
That's still O(n²)
Yes, use a while loop and exit as soon as the Value drops beneath k
Wait Nel, I've been thinking contiguous subarrays
That's why I jumped to hashing (and called it DP)
I can't really imagine how you'd code that, so I can't tell what's wrong with your approach
There's a simple¹ O(n) solution for this problem
-# ¹when you've already solved this sort of problem before
It’a gonna be using nested loops
Using ||prefix sums|| or something different?
How is it better than OP's first thought?
I didn’t say it was
Fair enough
Cuz if so this is what I've been referring to as hashing, cuz you use a hashmap
Not really
It’s faster because you start by testing the longest sub arrays first
Oh hmm
For an array of 1000 elements, all 1s, with k=2, that's not faster
@robust horizon I can try to guide you through this but it is a difficult problem for someone who has just started using arrays...
can i try?
Of course
what would be the very first step i should be thinking of?
Shush all arithmetic operations are constant time for simplicity
No they're right it's O(n^3)
No I know I was being facetious
Maybe make an example array and try going through it manually, keeping track of relevant things, and see if you can find a solution that way
okay, say the array is {1, 2, 3, 5, 9}; with n = 5 and, say, k = 10
we know that there's two sub-arrays which equal to 10, i.e., {2, 3, 5}, and {1, 9}
oh
Oh, before we continue, I should ask: does the question define a subarray as contiguous? It should, but we can't be too sure...
(if it doesn't this is np-complete)
i copy-pasted the problem
i am sorry
Fair enough, also I just realized how to do this without hashing lol I was overcomplicating
It's normal, you're learning
so this would not work?
Alright so it's almost certainly contiguous subsequences
No it wouldn't
Let me try making an example
{3, 2, 1, 1, 1, 1, 3}, k=4
That should do the trick
question, what happens if it is not contiguous? i mean it makes it more complicated, yes, but aren't we just checking if elements of the array equal the sum? like how does it make a difference?
It makes a big difference in complexity, because there are 2^n subsequences (not necessarily contiguous)
okay, but what if we skip that part? would we change our approach?
and there is no known algorithm to solve this in non-exponential time IIRC
It's np-complete yes
np-complete?
Well in this example if we're considering subsequences, you'd need to consider things like {2, 3}, {3, 3}, {2, 1, 3}, and so on
Essentially it's a class of very hard problems that can't be done in polynomial time (as of now)
even if they do not equal the sum?
i see, thank you
You won't know until you check
So you have to check still
How do you know whether they do before you even consider them?
You know how, if you want to find the maximum value in an array, you need to check every single element?
how did you get {2, 3}, {3, 3}, {2, 1, 3} again?
yeah
like, are we not talking about contiguous sub-arrays?
Well in this problem you'd need to check every single one of the 2^n subsequences, and that's potentially a very big number
right
We are, I was just demonstrating the difference
so basically kind of like all the power sets?
oh okay, makes sense now
It's the power set, yes
But, going back to your problem, you only need to consider subarrays, and those are the contiguous kind
can i state what approach i am thinking of?
Go ahead
i am not sure if this is correct but
{3, 2, 1, 1, 1, 1, 3}, k=4
okay so
we start from the very first element, 3
we check if the next element plus itself equals 4
it does not
we keep an index?
so we know it is not {3} or {3, 2}
or is lesser than 4
so we move the index to 2
again, we repeat the process
3 is <= 4
so it could be {2, 1, ...}
You mean 2 <= 4?
oh, yes, sorry
Ok, so you get to {2, 1, 1}
then 2, 1
yeah
we get a sub-array
whose elements equal to 4
now we move our index to 1 (the first one)
and so on
but isn't that a super long process too?
wait
isn't that what the first thing i thought of, was
Kinda, but it's a start
I should've asked too, is it an array of positive integers only?
Do you have a link to the question?
yeah i was gonna say, negative numbers would throw a wrench in his solution
it was shared to me by a friend as a screenshot, is it okay if i forward the picture?
Yea
so, this is not exactly what we are trying to think of here
Well it's not bad, just not optimal
I think you should implement your solution before trying to improve on it
Yes
If the problem included negatives in the array, you'd be right; I was already thinking of only positives, which has a (slightly) better solution
Also I found the source (spoilers because solutions): ||https://takeuforward.org/data-structure/longest-subarray-with-given-sum-k/||
question
so i would need to check for individual elements too, right
would that not result in a lot of ifs conditions?
Yeah, in the question's example there is a 5 in the array, and k=5
It shouldn't
||hashmap& prefixsum|| i think
can i work on it like how we work on the fibonacci series
like compute the nth fibonacci number?
i am thinking
say i find a sub-array which equals k
where do i store it?
or do i just remember the indexes?
The question only asks for the maximum length of valid subarrays
but we wouldn't know the maximum length until we have found all such sub-arrays, right?
Of course, but you don't need to remember all subarrays, just the maximum length
I don't quite remember but yeah probably
Problems like these challenges the optimality of your solution
You can brute force or use an effective algorithm and data structure or whatever else
um, something like this? #include <iostream> using namespace std; int main() { int a[7] = {3, 2, 1, 1, 1, 1, 3}, k = 4, sum = 0, max = 0; for (int i = 0; i < 7; i++) { for (int j = 0; j < 7; j++) { sum += a[j]; if (sum == k) { int l = j - i + 1; if (l > max) max = l; } } } }
honestly, i am just trying to think of how to implement it right now, no matter which way
well thats one way to do it but reset the sum
Did you mean to start j at 0?
ah yes, i
after sum += a[j]?
well outside the loop
right, sorry
You need to reset sum at some point
I'll also give you a small improvement: you can start loop j from 0 to n-i; that immediately gives you the current subarray length
i do not follow how
after each ith iteration?
or no?
Yes
using namespace std;
int main()
{
int a[7] = {3, 2, 1, 1, 1, 1, 3}, k = 4, sum = 0, max = 0;
for (int i = 0; i < 7; i++)
{
sum = 0;
for (int j = i; j < 7; j++)
{
sum += a[j];
if (sum == k)
{
int l = j - i + 1;
if (l > max)
max = l;
}
}
}
cout << "maximum length of the required subarray is: " << max;
}```
is okay now?
Should be
yay
Ok this is just details so I'll give you a version of your code that is functionally equivalent but reads better:
#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
int a[7] = {3, 2, 1, 1, 1, 1, 3}, k = 4, maxLength = 0;
for (int i = 0; i < 7; i++)
{
int sum = 0;
for (int j = 0; j < 7-i; j++)
{
sum += a[i+j];
if (sum > k)
{ // optional, to not unnecessarily go to the end of the array
break;
}
if (sum == k)
{
maxLength = max(maxLength, j+1);
}
}
}
cout << "maximum length of the required subarray is: " << maxLength;
}
Hopefully I didn't break it
i am trying to understand this: for (int j = 0; j < n-i; j++)
so
we start from 0
a[0]
I did break it, should've been sum += a[i+j]; (I edited just now)
True
You can also use size(a)
Sure
I'm gonna have to go, so if nobody answers, you can always just close and open a new channel
o7
okay, thank you so much for all the help!
for (int j = 0; j < 7-i; j++) does this not do something like this:
for i = 0, a[0] + a[1] + ... + a[6]
for i = 1, a[0] + a[1] + ... + a[5]
and so on?
Its supposed to be j < 7
they did that before, but then changed it to sum += a[i + j]
Well why?
i also still do not get how it would be a better solution
Oh
Your solution and their given solution is kinda the same
yes, they mentioned it is just for better readability
Well yeah other than that theres not much improvement
okay so now that we have figured this one
what would be a better approach for this?
Well using hashmap and an algorithm called prefix sum
i know prefix sum but i do not see how exactly it helps
which will give you a solution for both negative numbers introduction and O(n) runtime
what exactly is the functionality of hashmap?
Its stores the prefix sums
Basically instead of checking every subarray like your code
the optimal solution
uhm
It kinds of remembers the sums idk how to explain it
which let the code to not check alot of times and result in better runtime
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✅
wait
why does this not work for negative numbers?
like why does it matter at all?
negative numbers doe work on your current code but it slows it down alot
how so?
Because then there will be no early termination and keeping track of the sum is hard since it can now decrease instead of increase
They added sum > k here to avoid neg nums
yes but does that not mean that if we do not add that condition, like i did not, earlier, it slows the process down for positive numbers too?
that is just, bad?
Your code works fine for postive integers
though there is a better approach but it works
sum > k strictly prohibits negative numbers
this
not nel's code
Well its both O(n²)
Yes
it sure makes a big difference, no?
Yup
then why?
also how is this any different (better) than having negatives in our array
sorry if that is stupid
i am just trying to understand
both negative numbers and positive numbers results in the same runtime in your code
Now you got it
yes, thank you
Sorry for the brief confusion lol
I keep thinking that the original questions asked for positive numbers only
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why is it that for this question even tho we're just rotating 1 funciton around some axis, we have to use the washers method?? why is it not the disk??
i thoguht we're just rotating f(x) around the axis so i can just use f(x) - (-2) as the radius and then use the disk method
this is the solution, i dont rlly understand
because else you wouldn't had a hole
You need to remove the -2 distance because else you wouldn't get that hole
how can i know form the question that theres a hole..?
You are given a region
doesnt it just say to rotate f(x) around the line y = -2?
,, R = {(x,y)\in\R^2 : (0 \le y \le 4-x) \land (0\le x \le 4) }
you are rotating the above part
yea
OHHHHHHH
im tripping
tysm
but like
if it didbt say region between x axi
axis
and it just said to rotate f(x) around axis y = - 2
then i can juist do this right?
most likely
saying rotate f(x) doesn't even make sense
you actually need to specify a region
oh
@solar crest Has your question been resolved?
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Solve $log(3y^2-10) to the base 4=2log(y-1)to the base 4+1/2$
Tan
Tan
Tan
$\log_{4}(3y^2-10) = 2\log_{4}(y-1) + \frac{1}{2}$
did you mean this?
dont know how to proceed
\log btw
yes
Lute
this was wrong btw
you tried to do 4^ both sides, right?
you can't do that unless you've got JUST log(...) on the left and JUST log(...) on the right
i do tho
you still have the 1/2.
that thing doesnt just stay as-is yknow
oh
you need to simplify $2 \log_4(y-1) + \frac12$ into JUST $\log_4(????)$ (with \textbf{nothing} outside the log)
Ann
well i cant do anything abt it since if i subtract it from the rhs it appears on the lhs
you can write $\frac{1}{2}$ as $\log_4(4^{1/2})$
Ann
yes (which i told you to do to begin with)
personally i think this alternative is a bit clunkier than simply applying the function 4^x on both sides but like you do you
you go from $$\log_4(3y^2-10) = 2 \log_4(y-1) + \frac12$$ to $$4^{\log_4(3y^2-10)} = 4^{2 \log_4(y-1) + \frac12}$$ and simplify from there
Ann
yknow like, if a=b then 4^a = 4^b, you feel me?
does it, though? (referring to OP's now deleted message)
yeah
oh lmao rip message
Tan
this might be the worst texit message ever generated
i need to learn how to use this thing man
yes that you do
$b^{\log_b(x)} = x$
Lute
$4^{\log_4(3y^2-10)}$ does cancel out cleanly to just $3y^2-10$, yes. but on the RHS it is more interesting.
Ann
$4^/log*{4}(3y^2-10)*$
Tan
what's with the forward slashes
well u just use the power rule and make it4^log(y-1)^2 and then cancel right?
Tan
Compile Error! Click the
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(You may edit your message to recompile.)
and what's with the *s
im making it itallic
you don't have to
$\log_{4}(3y^2-10) = 2\log_{4}(y-1) + \frac{1}{2}$
those are underscores, and are used to write subscripts in latex.
Tan
YES
bases are not subscripts, but we write bases in subscripts, yes.
IM RIGHT FOR ONCE
why did it not appear in ur message tho
because I did not escape the underscores, nor did I intend to.
?
wdym escape the underscores
why did what not appear in Lute's message?
underscores are special characters in discord. you can surround text in one underscore (to either side) to italicize a phrase. surround a text with two to underline it.
wait in irl mathematics can we use _ to define subscripts like we use ^ to define exponents
to show surrounding underscores as is, you need to escape them.
no.
in real life you can write subscripts directly to begin with.
yeah but people get confused right
thats why they invented the carrot
karat
Caret
no. writing superscripts and subscripts properly makes people less confused than spamming _ and ^.
plus, the caret was not invented for this purpose, as far as I understand.
w this
what is your current step
log(3y^2-10)=log(y-1)^2+log4^1/2
i wrote 4^1/2 as 2
(btw all the bases are 4)
and now
i want to write the rhs as a single log
do i expand (y-1)^2 first or just multiply to get (2y-2)^2 and then expand
I don't see a need to do either. you can directly write the RHS as a single log from here.
how do you normally simplify log x + log y if they're the same base
then do the same thing here.
2(y-1)^2?
or
y^2-2y+1(2)
oh okay
i got
3y^2-10=4y^2-8y+4
(after cancelling log)
0=y^2-8y+14??
keep going
factors of 14:1,2,7,14
therefore
this question has no solutions
wait no the stupid formula
uhh
,w calculate 64-4(14)
Sorry, how did you get this line?
No, I mean
The last message you sent where like three of us responded
, that's correct
How did you get from that, to this?
Like, the RHS after cancelling logs became this
Did you misunderstand this to mean you square the 2 as well? (which is incorrect)
what
after cancelling log, it became this.
No, after cancelling logs it became " 3y^2 - 10 = 2(y-1)^2 "
Might I ask for a
!xy
Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.
I think we can proceed from here and explain why OP may be mistaken.
@urban wasp Has your question been resolved?
this
@bold turtle
I mean, show me the source
If it's from a book, take a photo
If it's online, take a screenshot
there is nothing more.
its just
Solve $\log_{4}(3y^2-10)=2\log_{4}(y-1) + \frac{1}{2}$
Tan
This
Okay, so do you agree with getting to this line?
no
$3y^2 - 10 = 2(y-1)^2$
Waes (Wires)
cuz i heard u cant cancel logs unless the coefficient is 1
y^2-2y+1
Right
So now we have two lots of (y-1)^2
i.e. 2 (y-1)^2
So what's this when expanded?
=(2y-2)^2
=4y^2-8y+4
No
2y^2-4y+2
There we go
parenthesis
Okay, so are we going to take those parentheses and square first, or multiply by 2 first?
?
This...
...is clearly not this
Okay but that logic is worse than shit I'm gonna be fully honest
Because by the same token, "4" is the same as "8" because half of 4 is 2 and a quarter of 8 is 2
so is this a super ultra rare case where it just so happens to be that they have the commutative property?
?
and it wouldnt happen with any other(or few) equations
No this is more of an ultra rare case where your algebra needs more revision before continuing with logs ngl
2x^2 = 2 times whatever x^2 is; it is not equal to the square of (2x)
bro i even need help with addition and subtraction
sometimes i subtract things from the rhs and accidentally add them on the lhs
but yeah
thanks
Honestly at this point that's something you yourself need to practise
A person typing on a screen can only go so far to explain those concepts
i practice 3 hours a day
addition, subtraction,multiplication, and division
...That's arithmetic
oh
Not algebra
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You're thinking of arithmetic sequences (which you haven't described properly)
Those are called arithmetic because you're adding/subtracting between consecutive terms
so i suck at arithmetic
Similarly "geometric" sequences are so called because of having common ratios between consecutive terms
no wonder i always get polynomial questions wrong all the time
Arithmetic, the gerneral term, just means addition, subtraction, multiplication, division etc.
i.e., doing numerical calculations
i see
arithemtic is usually just addition
calculators like wolfram can do more than arithmetic right
yeah they can do a lot
,w differentiate 3x^2
I'm talking about elementary school arithmetic, i.e. numeracy
That context is important
yeah
,w integral 3x^2
(and you'd missed the entire context for it lol)
im in hs..
who needs arithmetic skills when you have a calculator /s
ik, else you wouldn't be doing logs
But what I'm talking about is something that should be taught in elementary/middle school
That being said, I'm guessing you're from the US?
nah we havr to do 2 papers one without calc and one with calc so yeah
in high school??
yeah
i.e. the land of no regulations on their maths syllabus so fuxk me if I ever understand what's on their papers
for cambridge
oh dude i feel bad for you
bro
without calculator i literally cannot function
worth like 180/320 marks each
one mcq, one open-ended, one practical
nope
but guess what
ik someone who can
,w solve $\log_{4}(3y^2-10)=2\log_{4}(y-1) + \frac{1}{2}$
nevermind
That shit only flies if you can acc type the question in properly
,w solve $\log_{4}(3y^2-10)=2\log_{4}(y-1) + \frac{1}{2}$
wait a fokken second
just replace all the y with x
,w solve for y $\log{4}(3y^2-10)=2\log{4}(y-1) + \frac{1}{2}$
WA loves its exes
It's got so many exes
hang on
did you mean $\log_4(3y^2 - 10) = 2\log_4(y - 1) + \frac{1}{2}$?
0
Humans are idiots; computers are just really fast idiots
yes
,w solve for y, log_4 (3y^2 - 10) = 2log_4 (y-1) + 1/2
There we go
Incidentally that's what I got by hand as well
i should have checked your arithmetic
combine the expression on the right into one log
that ship has sailed
So, 0, we've already gone through that
anyway, OP, do you agree with WA's answer now
We've gone as far as $3y^2 - 10 = 2y^2 - 4y + 2$
Waes (Wires)
ohhh
yeah that
i did it alr
just need help with basic algebra and arithmetic calculations
that, we shall see you in #math-discussion ir #study-discussion unless you have specific questions
cuz help channels are not the place for a crash course in topics
but btw OP, just curious. are you above 15 years old?
remember when you taught me the laws of square roots
nope
who
you
oh
i see. i guess you're a peer then
hollup lemme try find it
what?
what
Sense 1
not exactly sense 1
Well, ... okay yh
peer here = same age
oh ok, cool
WHAT