#help-10
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that is why 8√10 + 60 is the final answer
🤨
well you're at the very start of algebra, thats where most students struggle... but once you perfect everything, math will be very easy! atleast until like college or smth
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so it was comparison test im assuming
The previous part was
Would I let B_n be 1/n^2
Idk how to really make these into formal proofs
Since
I only have done A level proofs like this which are nowhere near rigorous
It would just be cancelling
How would I go about this kind of proof
Is that what it’s called?
limit comparison test yea
but did you try working it out with your choice of b_n
what did you get for lim a_n/b_n
I’d get 1 for bn = 1/n^2
yep
so what does the conclusion of the theorem here tell you
That an and bn converge?
It would only converge if and only if a_n converges
🤔
sure but we know it converges
if we don't know that either of them converge then its useless
b_n converging implies a_n converges as well
yes
Idk what u mean by conclusion
🤔
we found a b_n > 0 such that the lim a_n/b_n = l \neq 0 so the conclusion of the theorem here tells us that b_n converges since we already know a_n converges
Oh I see
So what use does this test rly prove, the fact that the sequence we thought of converges?
it offers a simple way to show a series converges?
not sure what you mean
In this case, b_n?
🤔
we're showing a_n converges by comparing it to a known convergent series that we speculate behaves similar to a_n
yep
you're welcome
Sorry I just had one last a
Q
Would this be sufficient?
Or should I show the division by n^3
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also you should write $\sum b_n$ converges so $\sum a_n$ converges
knief
i was just referring to it as b_n and a_n in text to avoid using latex
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I really dont understand part b
part d oops
ok so if you put x=0.01 into the original expression you get 1.01/sqrt(0.98) unsimplified, yes?
you see the last line of the MS, idk what is going on
do you understand the second M mark
kinda yea, but id prefer if you can explain it
$\frac{1.01}{\sqrt{0.98}}$ simplifies down to $\frac{101\sqrt{2}}{140}$ when you rationalize and remove all fractions-within-fractions
Ann
and then $\frac{101}{140} \cdot \sqrt{2} \approx 1.02025$ --- from here you multiply both sides by $\frac{140}{101}$ in order to get $\sqrt{2}$ on its own
Ann
yes exactly
tbh the way the question is worded is kinda weird to me
it's a weird source of approximations for sqrt(2), tbh.
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it just says $\vec{CA}$ with the coordinates of A (2,5) and C (8,6)
opal
Hmm, can u send the exact problem statement?
Are u supposed to find the vector CA?
CA = A - C,
(2 , 5 ) - (8 , 6)
theres no other information the rest is of the problem is 6 other vectors that i alredy solved
if you wanna understand where CA = A - C came from, I can elaborate.
components
wait
what is C - A then
AC?
oops
-AB is BA
C - A = -AC
oh yeah
well, with examples like AB = B - A, notice how the latter letter of the vector's name is the one that's written first
so why do we do A - C and not C - A how do u know
so smth like K - D should be equivalent to DK
gotcha
if the question is asking for CA
then that is A - C
if you do C - A
ohh
you are getting AC
its not -AC?
what is?
C - A
C - A = CA = -AC
this AB = B - A shtick also expalins why AB = -BA
AB = B - A
BA = A - B
the difference between 9-3 and 3-9 is the -
BA = A - B
BA = - (B - A)
BA = -AB
np ofcourse
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there's one last thing I could say
yeah?
gotcha
want to
.roeopen
continue
.reopen
yes
✅ Original question: #help-10 message
if you have this rod, where A marks 3cm of it and B marks 6 Cm of it, what is distance AB equal to (in cms)
B-A
exactly!
AB = B-A even in lengths! (which work for vectors Ofcourse)
now you can close 🤩
unless you have other concerns
but what if A was 6 and B 3
well that means B came before A
oh BA then right
yes.
i was thinking of this image (sorry)
i see
🤩 dw you can close now
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✅ Original question: #help-10 message
@fossil pendant got 1 lat question
why do we do A-C to find the components for CA and not A + C
what is adding 6 and 3 here gonna contribute to evaluating AB?
well yeah! if you are given the coordinates of point A and C then you can get CA by substracting C from A (A-C)
we know CA= A - C
and you got both point A and C
do you know how to substract** points** 🤩
...
def use your calculator
😭
wait i got the coordinates wrong
hm?
it was A (2,5) C (8,6)
mhm
+?!
oh mb
the A is positive no?
cause 5 is in A and A is positive
like C would be -(8,6)
A - C is
(2, 5) - (8 , 6)
which is translated to
( 2-8** , **5-7 )
your + here suggests (-7) which... is not a point
atleast in 2D
so everytime i want to find the components i gotta subrtract
what does it do if i addition?
try to not memorize "the way you do it" but rather "this cou8ld be helpful in some situation and its good information to know" so that hte solving process becomes more intuitive
yeah true
hm...
A + B = A - (-B)
calling point -B as U
it gives us the vector UA
not sure what you wanna do with that...
I mean- If you are given A+B
in some situation
It could lead to... another thing that could be useful?
depends on the context ig
like if you have the points A , B
and you wanna be... goofy
and get BA from A+B for some reason
you can substract B twice
A+ B - B - B = A-B = BA
...ig? 😭
hey! expiermenting with math makes it a lot more intuitive
you'll def benefit if you do weird random stuff as long as you get the logic behind them
logic is my problem in these things
again, DEF try to not "remember how to solve this" and do "Hey I know this and that, let me think of how i can use the information ik to answer the question"
yeah
when you get into calculus, you'll realize that UNDERSTANDING what you're doing and what you're trying to achevie before proceeding to solve the question is what makes it "hard"
its not hard. Its just not taught properly, sadly.
facts just gotta practice a lot to understand
see me when you get itno trig sub for calculus 2!
its all about
"yeham, what can i do here 😭 "
anwaysy!
yes, any more questions?
all g nah ima continue and see if im stuck anywhere
ofcourse.
ty man
np opal!
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hey, ive just got a few specific questions on my study guide for my upcoming exam. Can someone hop in vc to answer a few questions?
this is just an example
hold on ill send the whole thing
actually i might have to afk soon but just ping me
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.
What happens if you scale a vector
(multiplying by a scalar)
it becomes 0
like scalar product right
both coordinates multiplied
oh alr
USS-Enterprise
so 1/2(50)
What happens to the direction when we scale the vector by $\frac{1}{2}$
USS-Enterprise
Try drawing it if you don't know
it becomes 25
Yes, the norm
The norm is simply multiplied by the ||absolute value|| of the scalar
Why the absolute value?
Say it was -2*u
Then the norm would be 100, right
a vector cant be negatif
yeah
Otherwise we would get -100cm
Which is not really possible
Okay, but what about the direction
Draw a random vector u, and then 1/2*u
i drew a vector and split it in half
Yes
the direction remains the same because its not -
Correct!
When multiplying with a positive scalar, direction remains unchanged
1/2 * u has the same direction as u
But when multiplying with a negative, direction "flips"
yeah
-2 * u has opposite direction as u
true
So 360° - direction of u
Well you can't have a negative norm 😅
If multiplied by a positive scalar, such as 1/2, yes
Think of it as just "extending" or "shrinking" the vector
You are keeping it in the same direction
When you multiply by a negative scalar, you do the same thing, shrinking and extending, but you also flip where it's pointing
yeah
opposite sides right
Yes
gotcha alr thanks
Of course
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✅ Original question: #help-10 message
ah
gotcha
Always the absolute value of the scalar
$\absolute$
but how do i find the orientation
USS-Enterprise
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
yup
how do u know if its in the 4th quadrant
because when its in the 4th quadrant u do 360 - <
alr
We just add 180°
to get to the other side of the line
And subtract 360° if we are over 360°
i see
Right so 310 + 180 = 490
like this?
And then 490 - 360 = 130
Yes, exactly
gotcha alright
The angle between a vector and its opposite vector is 180°
Yeah
alright tysm again
no problemo
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<@&286206848099549185>
!15m
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What do you need helpers for???
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Please send the question first, wait, if 15 minutes pass with no help then ping helpers
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can someone check that ive done this correctly?
11 (a)
why is it written like integration by parts?
oh i thought thats how to do it
nah just use substitution
ok i see what happened
2x+1 is the angle which is going in the sine function its not another function
sin(a) but a is 2x+1
you substitute it as something else you know integration by substitution ryt?
thats integration by parts used when two functions are multiplied
You performed integration by parts, not u-sub. They are not similar methods. It happens! But you might want to find a source on u-sub.
look substitute 2x+1 as u and differentiate both sides
I hope someone will! My personal suggestion: Youtube will be faster than us, since you've never seen this method be completed before.
yeah search integration by substitution it will be easier to understand that way cannot explain in text
hm
i have
i just dont get it
but ill look
thanks
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Let f (x) = x2 + 19. Express f 0 (4) as a limit. I would just need to plug in 4 correct?
f0(4)?
do u remember the first definition of derivative
okay i give u a easy one f’(a)= lim x->a f(x)-f(a)/x-a
this is a simplified version of the definition
yeah
I'm confused
You are finding the tangent slope of a point on the function, so you would pretend to take 2 points, find the slope between them and move the points closer to each other until the difference is infinitesimal
-16-19
Yeah
a^2-b^2=?
c^2
it is called difference of square
oh okay
x^2-16/x-4
just think it is a number
is that the answer?
no x^2-4^2=??
x^2-4^2=x^2-16
can I have the answer so I can work backwards and see where I'm misunderstanding?
so I'm just confused iif I should just follow this slide with what we are trying to solve above
do I repeat the formula shown in the slide with this?
yes
ah gotcha
thank you
ill give it a go
so
it's x^2+19-16/x+19-4?
am I on the right track?
It's because 19 is still in the equation
Let f (x) = x^2 + 19. Express f' (4) as a limit.
The equation is for f(x)
Oh
There's no f(x) in the denominator
As in it represents everything
it's x^2-16/x-4?
This is nonsense
Just put parentheses and it's right
Well no f(x) is representing the entire function we're evaluating meaning yeah putting the +19 does nothing
I get what you mean now
it's (x^2-16)/(x-4)
Thank you
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Ahhhmmmm...
so part ii) are we meant to use the cosine rule? or
I tried using cosine rule it got me that z = z
which is great and all but
not quite what i was looking for
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Since 𝑨𝑫̅̅̅̅ is the median over 𝑩𝑪̅̅̅̅̅ of the triangle 𝑨𝑩𝑪,𝑬 is a point on 𝑨𝑫̅̅̅̅ such that 𝑨𝑬=𝟏/𝟑𝑨𝑫. The line 𝑪𝑬̅̅̅̅ intersects 𝑨𝑩̅̅̅̅ at 𝑭. If 𝑨𝑭=𝟏,𝟐 𝒄𝒎, Find the length of 𝑨𝑩̅̅̅̅. The drawing is mine
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
Do yk mass points?
Nop
Either but yes harmonics
Idk menelaus' but i know how to use harmonics
as in cross ratios?
Kinda
Like harmonic points, harmonic beam, descartes relationship
newton relationship
harmonic quatrains
hm cause I was thinking of having you show ||AF/FB=(EA/ED)(DC/DB)|| but idk if imma be on the same page as you
So imma leave this to someone else
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Proof Help Needed
@tranquil tide Has your question been resolved?
what if you show triangle ACF is congruent to triangle DBE?
I get that you can porve angle FGB is congruent to CGE with vert. ang. congruence thm, and GBC to GCB with congruent supplement thm, but after that I dont know where to
how would you prove GB is congruent to GC?
if you drew a perpendicular from G to BC it should make congruent right triangles
so maybe it's a property of isosceles triangles
like, two congruent angles should be enough to make it isosceles
In geometry, the theorem that the angles opposite the equal sides of an isosceles triangle are themselves equal is known as the pons asinorum (/ˈpɒnz ˌæsɪˈnɔːrəm/ PONZ ass-ih-NOR-əm), Latin for "bridge of asses", or more descriptively as the isosceles triangle theorem. The theorem appears as Proposition 5 of Book 1 in Euclid's Elements.[1] Its converse is also true: if two angles of a triangle are equal, then the sides opposite them are also equal.
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okay so what the hell is even happening here i was so sleepy during my math period
This algebra 2 and precalculus video tutorial focuses on graphing exponential functions with e and using transformations. It explains how to find and write the domain and range of the function in addition to identify the horizontal asymptote. It shows you how to use a data table to plot at least two points to draw an accurate sketch of the gra...
bleak
sorry
ok ok i'll see
khan and org chem tutor are just good at summarizing
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Can anyone help, I’m lost
Which part are you lost actually?
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how can i solve the 6d question, that f(x)=x²-3x+2
If I'm not misinterpreting, you're asking for a way to find values of a and b?
yea yea
Right, first you have to plug in f(x)
yes
Then since we have a+3b = 1
Manipulate it that one of them is a term of the other
In simple terms, make a in terms of b or make b in terms of a
oh no, like check if that statement is true
Right so, it isn't asking for values of a and b?
Wait, what's the actual required?
Right then, what's the purpose of a+3b=1?
we check if a+3b=1
If that also has to be true then we can assume that a+3b=1 can be used
Since we have to make sure the conditions of the limit is also meant, right?
what if it is false
But we have to find potential values first
And if we can't find it then we can say it's false
Right, what if we do it like this
We find the limit of the denominator?
Since a and b are in the denominator
Let's not make use of a+3b=1
Hmm actually we could just first find the initial limit of the function then go from there
yea
Let's find the function first, you should be able to get 0 on the numerator right?
0/(a+b)
So we need a value a+b to make it 2, right?
But no matter what we make it will equal to 0. Right?
But if we have a+b=0 then wouldn't it become an indeterminate form thus having the possibility to achieve the finite number 2 if simplified
So, what do we have so far?
What conclusion can you form on the value of b so far?
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Hello, I need help with an exponential decay function problem, please!
The problem is: Cesium-137, with a half-life of 30 years, is one of the most dangerous by-products of nuclear fission. What is the annual decay rate for cesium-137? Write the answer as a percentage.
No, I'm having a hard time figuring out how to start the problem.
Right, so for how many years, the amount of the compound(Cesium-137) will be halfed
30
I'm not sure how to do that without an initial value
Let’s say the initial value is k
I'm clueless
I’ll give one more prompt before demonstrating it
Look, for every 30 years, the amount of the compound becomes half of its initial amount
k(0.5)^t/30
that was a guess, I don't understand what t means in this case
$\text{V} = \text{V}_I (0.5)^{\frac{t}{30}}$
Approved Freak
It means the years elapsed
When t = 30, meaning that it has reached 30 yrs
The initial value gets halfed
Do you agree with this?
yes but I don't quite understand how t/30 expresses this
30/30 =1
0.5^1 =0.5
Halfed
Ok I do get that
When you plug in t = 60, you’ll find the same pattern
The value gets halfed and halfed again
Which is 1/4
right
Alright, how about 7.5 yrs?
7.5/30?
Don’t forget 0.5^
ah
How about 1 year?
0.5^1/30
ah lol
Anything else you wanna ask?
No, I think that covers it. Thanks so much!
actually
It says to write it as a percent. But my attempts are being marked incorrect
when I calculate (0.5)^1/30, I get ~0.9771599684
not sure what I'm missing
Can I check the original question?
,w calc (0.5)^(1/30)
I've tried 97, 98, and about 20 other variations
it's an exercise problem, so I have infinite attempts
<@&286206848099549185>
Hard to answer without know exactly what you typed
I could see it expecting 1-x, so like 2.28 or 2.3
I've tried exactly:
97
98
96
2
2.28
978
.978
7
just kinda doing random guesses at this point
2.3 is also incorrect
2.27 is incorrect
2.29 is incorrect
both incorrect
Sorry that's just wrong, it would be 97.7
How many characters can you input
(0.5)^(1/30) ?
but I believe my curriculum prefers 4 digits when rounding
so perhaps that's it
4 digits would be 97.72
I tried that as well, it was incorrect
or 2.284
sorry, I mean 4 digits after the decimal
You might as well try 0.97715996843424595493269814617765452366631293874787179003507567484943108652 

the question is, why lol
ah that makes sense
I understand it all now. thank you so much!
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Calculus again. I'm not sure how to find the derivatives or even if my original answers are right. I can't easily find the process in my book.
when the derivative is positive, what does that mean for the graph?
derivative is slope of tangent line right
I think so.
so do you understand how to tell whether f' is positive/negative from the graph?
you look at the slope
Ok. So how would I get the second derivative?
you look whether its a U shape or a Ո shape
concave up vs concave down
concave up -> f'' positive
concave down -> f'' negative
have you filled it out for the first derivative yet?
@idle lynx Has your question been resolved?
i think i missed the context — what are you trying to check?
@tulip prawn
sign of derivative just means increasing or decreasing
increasing means positive
decreasing, negative
I understand that, I'm not sure if it's correct or not now.
its correct
what?
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can someone show me the step by step proof? with explanation. I dont get it from my notes. i dont even think what i have on my book makes sense.
where is the dt coming from?
f(t) = sin(t)/t dt
the dt is baked into the integral notation
what?
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they call it Si(x) for a reason mate
zedias
jesus christ

\FT Why are you trying to find
[
int frac{sin x}x dd x
]
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"(f) find Si’(x). Hint : apply the FTC part 1"
So I’m trying to find that integral but from 0 to x?
You’re trying to find the derivative of Si(x)
[Si(x) = int_0^x frac{sin t}t dd t]
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Yep, by the FTC part 1 it's that simple
If you want to check, solve the integral for Si(x) and seek for the derivative Si'(x) 😅
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hi could u help me with set
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so i thought i knew how to do this question
selecting 1 question from each section is (4C1)^3
and selecting remaining 2 from 9 is 9C2
the answer keys says A
i js wanna know if i did it the right way
well you gotta be careful with that
let's say you pick A1 B1 C1 in the (4C1)^3
yes
then, idk, A2 B2 as the other 2
yes
well what about when you pick pick A2 B2 C1 in the (4C1)^3, and then A1 B1 as the other 2
one of the possivilities
hm there are a few ways you could do it
i have no idea how i could calculate the repeating cases
the possible amounts from each section are
1 2 2
1 1 3
so you can have e.g. 1 question from A, 2 from B, 2 from C
with a 1 2 2 "structure" there are 4c1 * 4c2 * 4c2 ways to select questions
there is also 2 1 2 and 2 2 1, so more like 3(4c1 * 4c2 * 4c2)
oh so instead of doing them one by one
you just choose from 1 section by one expression
oh man thats like brute forcing
wait no
its the same numbers
ah still
,calc 3(4 * 6 * 6) + 3*(4 * 4 * 4)
Result:
624
if there was a way to count the repeating cases tho
that sounds more difficult
like my method gives rise to the expression 3(4 * 6 * 6) + 3*(4 * 4 * 4)
how much simpler could it get
i dont get it
the first part is all 1 22 22 1 etc
same thing with 1 1 3
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✅ Original question: #help-10 message
hmm this is the question now
fixing 1 at one of the one place(out of n) and selecting 1 number out of two for (n-1) places gives me n[(2C1)^{n-1}] ways to ensure 1 is present , for 2 its also the same. So the total becomes 2n(2)^{n-1} which is just n(2)^n
if this is the right way then how do i solve n(2)^n = 510 
There's an easier way to do this lol
How many numbers are there with n digits if you can only use 1 and 2 (no restrictions)
And how many of those numbers have no 1s or no 2s
2^n
there are only 2 strings that don’t use at least one of each
Layla don't spoil smh
oh js 2
slight interruption to say, smart move
Yes
512 - 2
sorry i was not really reading your messages, my message was just going to be my hint
goddamit
It is often easier to work without restrictions and then exclude them later
No worries
sometimes its easier to complete the restrictions first but clearly i should have tried two methods
Yup there isn't a general trick to which is better
“at least one” is a pretty good indicator
i really need serious help with this one cuz i have no idea 💀
making rectangles and squares involves choosing some points on the board to be vertices
clear version
how do i ensure they are squares
perhaps it would be wiser to consider the number of lines involved in forming a rectangle
for example if you choose any two points that aren’t on a line, that corresponds to a rectangle
and there will be one other choice that corresponds to that rectangle as well
wait i dont get it
this question is such a pain
2 points have to be on the same line to be rectangle
so many to consider
not necessarily
wait we have to count the diagonal rectangles too?
yes :P
let’s imagine a smaller board that look like this:
O O O O O
O O O O O
O O O O O
O O O O O
if i just choose 2 of them, let’s say
O O O O X
X O O O O
O O O O O
O O O O O
do you see how that corresponds to a rectangle?
no, I don't think so
Huh no
really?
It explicitly says the rectangles created by the horizontal and vertical lines
you are told that you are to form rectangles and squares with only the 9 horizontal and 9 vertical lines
ohh whoops
yeah
i didnt see the question
that's why I brought up the idea of considering how many lines you need to form the rectangle
the other two points will be
X O O O X
X O O O X
O O O O O
O O O O O
yea
right
and it’s worth noting that when you choose those other 2 points, you’ll get the same rectangle
yep perfect
i have to choose them 2 at a time right?
k
wouldn't considering the lines directly be more straightforward
what do you mean by that
id like to hear explaination about that too
you are given 9 horizontal and 9 vertical lines
you know a rectangle has to have two distinct horizontal and vertical lines each
so do some combinations
and bam, no minusing needed
well some minusing needed to account for squares, but way easier to account for
it’s like the same thing i think
it should end up being the same, indeed, but you'd have to count the number of points collinear with the chosen point for the point-based method
but whichever method OP prefers
how do i count squares?
Let's say your lines are divided into parts
Squares are rectangles
So you don't need to minus that ig
i have a dumb way if nobody suggests anything better
The wording of the question is ambiguous wrt that
that's fair as well
Same 
ok, too crowded here, I'll back out
k
You can choose same number of horizontal and vertical to form square
so assuming 1 square to 1 unit square area, you are saying to choose lines based of their unit length
i’ll just share the dumb way in any case: ask yourself how many squares of area 1 there are, how many of area 4, and so on
you can count the number of points you can lay, say, the top left corner onto
goddamn thats hard bro
Yes first 1by1 then 2by2
Ts easy trust me
At the end we get summation of n^2
let me try the calculations
Yeah ts what I'm trying to suggest
thats brute forcing and hurtful to do
tbh
doesn’t sound that bad to do in my brain
you can write a nice expression for how many squares of each size there are
can i use some type of combination to count the squares
i’m trying to think of a better way but i don’t think the working way is that objectionable
one part of the problem is intellectual and the other is pure mechanical work
very misleading 
there shouldn’t be that much mechanical work
let me try to generalize how many square can be made cuz im not counting them
for area 1, any of the 64 tiles will do. for area 4, you can choose 64 - 8 - 7 tiles as the top left tile of the square
for area 9, similar thing. just can’t use the bottom or rightmost 2 rows/columns
there is not really any brute force counting here
49 for 4 units
hmm 👍
so im basically just going from easier to harder doubts , this ones the last i swear(for today)
you may wanna look into ‘double factorial’
that’s exactly what your question is about
10000 factorialdivided by all factorials of even
can procced with this
oh i didnt know that
but it can also just be reasoned through, you don’t need to look anything up
howw
why don’t you start with this and factor some 2s out
see i have an idea
exacylu
all power of twos
threes
5s
..

thats why i cant reason through
i know how to factor them out
but there are so many prime numbers
well not ALL
there are so many
oh then you have divide them by lets say x prime factor and add the quotients up too
to get its power
we are working with 1000!/(1000 * 9998 * 9996 * … 2) right
ten thousand
oops, pretend i wrote that correctly
factor one (1) two from each thing in the denominator
it should look like one of the answers
10000 = 5000*2, etc
2^5000(......)

