#help-19
1 messages · Page 76 of 1
they have a shift tho
what was the transformation
oh no that’s at 2
not zero
nvm
The red curve is the sine wave, and the blue curve is the cosine wave.
I know that it's an integral with a lower bound of pi/4 and an upper bound of 5*pi/4, but I'm unsure what to put inside the integral.
This is a better image:
Red curve is sine wave, and blue curve is cosine wave. Need to find the geometric area of the purple region.
I don't know where to begin.
Should I do this integral?
$\int_{\frac{\pi}{4}}^{\frac{5\pi}{4}}\left(\sin\left(x\right)-\cos\left(x\right)\right)dx$
Vanouper
Don't know if I should do this for solving geometric area.
integral from a to b of |f(x) - g(x)| finds the area between f and g on that interval
in this case, the integral you have is correct
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What's up?
Can someone breakdown this formula |pn| = sqrt( (a1*an)^n )
geometric progression
What is this used for?
what is pn
|Pn|
thanks, i understand now
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Show the formula and its entire context
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how do i find x and y so i can do the jacobian matrix
hint: there are two expressions in terms of x and y that show up a bunch of times
an equation x and an equation y
ah i think i see it
ok wait so i tried to isolate the x and the y and set them equal to each other then solve it for that but that didnt work
you want 2 new variables here. define them in terms of x and y, then you can solve for x and y in terms of those variables
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Hey so if the original function is a one to one, then the inverse is also a one to one, or is it just an ordinary function?
Well, what does one to one mean?
A one to one function is one that passes both the horizontal line test and the vertical line test
bijections are invertible, yes
OK, so another definition is that each input has a different output. No two inputs have the same output. That's the horizontal line test.
Does that make sense?
Yes
OK, so the inputs and outputs are kind of paired up.
Yes
Which means that those same pairs apply when you have the inverse function.
So, that means that the inverse will also be one to one, since each input to the inverse has only one output.
Sorry, each has a unique output.
But in order for a function to have an inverse, it must be a one to one function
So does that mean that any function that has an inverse, the inverse is a one to one?
Yes.
Each input in the original function is paired with a unique output.
Like f(x) = 2x.
(3, 6) is one pair.
Nothing else has 3 as the first element of the tuple.
Okay
Also, is this graph I drew wrong?
Yes.
You change the x intercept to a y intercept.
Then you use the reciprocal of the slope.
So, that's f(x) = 1/2 x - 1.
Idk where I got this point from
I make a lot of silly mistakes for some reason, like just brain farts
It's easy to make mistakes in calculations and small things.
But it happens to me so often
Idk y
Anyways, I think that’s the only mistake I made
Yes, that looks fine after it becomes a line.
Aside from the red point my graph seems right, yeah?
Yes.
Yeah
Are these graphs I drew correct? (Last image is the answer key)
If they are wrong, I think I know why… I inferred these points
a looks good.
b looks good.
c looks good.
So, those all seem fine.
It's easier to notice that they're piecewise linear functions.
So, you only need to handle the x values where at least one of the lines changes slope.
And the leftmost and rightmost points.
If you get those points correct and then draw lines between them, that will work.
So I did this right
Someone told me that I should do more points than I think I need so I just did as many as possible
You can just do x = -6, -3, 0, 3, and 6.
The thing that I was confused if I did right was thst the most right and most left values in my table, I inferred. The line didn’t reach it yet but I knew it would so I did them
Is that ok?
-6 and 6
Yes, those are fine.
Yes, that looks fine. You just need to do the endpoints.
So, (-6, -4) becomes (-4, -6) and (6, 2) becomes (2, 6).
Then you just connect the points with a line.
Oh so I’m being extra
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Can anyone help figure out the order of steps?
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hi
any idea what f(x-2) means?
doesnt it mean shift down
no
it means shift to the right
If f(x) = 1/x then f(x-2) = ?
shift to the right 2 units
yea but i mean if you plug in x-2 for x
you get 1/(x-2)...
so g(x) = 1/(x-2) + 2
you can plug in thinggggs for x
adonhs
yea you simply plug it in
hence now you know g(x) and should be able to fill up the table
For the g(x) = 3f(x)
you can determine first f(x)
and then multiply it by 3
how would u graph that?
no cuz when i graph it- it doesnt join the line
okay
what happens if you multiply the function value by 3?
.
f(x+4) + 3
that's something total different
i bet you used the old g(x)
@granite ruin Has your question been resolved?
,rotate
so i assume this reaction was fake lol
so you dont get that you can plug in things into a function
x -> input
f(x) -> output
say f(x) = x²
if i plug in a for x then i get f(a) = a²
if i plug in x+1 for x then i get f(x+1) = (x+1)²
@granite ruin
it’s just confusing cuz u have one then u see all these other numbers
i get it a lil now
thanks
"then you see all the other numbers" ok
i just dont understand what you struggle with
so i can help out
it’s okay it’s late anyways it’s probably because of that
i’ve been out all day 😢
i’m sorry
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You cut off the top right
!15m
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Plug in t=0
For g
Into the equation
I did f and e
And then 180
I’m confused on what it means when it says stop
For g?
Alright thanks
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What kind of triangle is TAO?
It is not specified
But you can figure it out
What is the measure of angle TAO?
Remember, TA is a tangent line and AO is a radius
Is it 90 degrees
Right angle triangle
Oh now I can use trigonometry
Indeed
Oh thanks
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RRR GGG BBB
what are the chances of selecting 3 Greens from this list ^
its combinatorics i believe
3 greens in a row? with or without replacement?
3 greens in a row yes, wdym by your second quesstion
okay well so my actual question asks me to calculate EVERY individual possible out come
so not 9C3
but like
show calculations of each possibilty
His question is, after selecting a letter, do you put it back in the list when you make your second sellection
when i take a green out, is there RRR GG BBB left?
no
wait
when selecting 3 yeah ofc
but
like in the overall question of calculating EVERY single possibility
no
so like
every time you choose 3
it goes back in list
and choose again
do yk what i mean?
so just a 1/3 chance of getting green each selection?
honestly idk
the question is
Calculate the chances of EACH possbility happening with the following: 3 green, 3 blue, 3 red
and like to start it off i wanted to calculate the chances of selecting 3 greens
but
idk how to do iit
weird question
no?
so 84 different combinations
depends
on?
is GGB different than BGG for example?
no
same thinng
i know what you mean
it would be different if it was permutations where order does matter
do correct me if im wrong please
👍 im not very confident at this
ok how 9C3 then?
I think it would be 9C3 because we are selecting 3 colours right? out of 9 possible options
and order does NOT matter
so
bbg is same as gbb
bbg and gbb is ONE combination of colours
it would be 9 choose 3 if it were 9 distinct colors
oh
how would i go about doing it then?
you can think of it like...
there are better ways than this but this is pretty straightforward: you can have 0, 1, 2, or 3 Rs. in each of those cases you can count how many ways you can make combinations with Gs and Bs
but that's a naive way, there is a good formula for this
but also i'm curious what is this question from
So would I have to count through calculations or would I like list them down
It's a "challenging" question the teacher gave us as homework
I thought it was easy at first
But there's a lot of possible outcomes
So I'd need a lot of calculations to calculate all of them
ok and what exactly is the question? you've posted a lot of fragments of it
do you have a pic of it?
Well she didn't give us the question, she just read it out loud and I wrote it down
I have written down
💀
Calculate the chances of EACH possibility happening with the following: 3 green, 3 blue, 3 red
And I can only select 3 at a time
tbh are you sure you are selecting with replacement
as in are you sure letters don't disappear when you select them
it's a little weird to have 3 green, 3 blue, 3 red if so
also don't you need to list them all out anyway to state the probability for every one of them
Okay so when selecting 3 colours from RRRGGGBBB
Say I select Red as the first one
Then I'll have RRGGGBBB to choose from
I misunderstood what you guys meant earlier but yeah they disappear when I'm selecting but once I've selected my 3 so like say red green blue, that's one possibility so I start over again to look at other possibilities
Yeah
lol ok
you can use this to list them all out then
Green Green green
Green green blue
Green green red
Red red red
Red red blue
Red red green
Blue blue blue
Blue blue red
Blue blue green
Green red blue
Wait
Oh shit I did it wrong one sec there's a lot more
Wait did I
💀
i think there should be 10
Yeah I counted 10 too
and yea that list is right i think
How would I go about finding the possibility of each combination
GGG, RRR and BBB are the easiest ones
let's take GGG
we need to get a green, then another green, then another green
know how to calculate the probability for that?
definitely not, that's greater than 1
Oh
and syntax is kinda bad
doesn't matter bc both are wrong but is that (9!/3!)*3! 9!/(3!*3!)
Wait wdym
it doesn't matter lol but i was just recommending not writing 9!/3!3!
it's hard to interpret what that is
yea definitely
what's the prob we get green on the first selection?
i mean theres 3 greens
so theres 3 possible greens that I can have in the first selection
1/3?
yep
yea
yep
,calc 1/3 * 1/4 * 1/7
Result:
0.011904761904762
Result:
1.19
thats the %?
yes
oh ok
Green Green green - 3/9 * 2/8 * 1/7
Green green blue
Green green red
Red red red - 3/9 * 2/8 * 1/7
Red red blue
Red red green
Blue blue blue - 3/9 * 2/8 * 1/7
Blue blue red
Blue blue green
Green red blue
how would i go about finding the other ones
those are trickier
take ggb for example
with order considered you could draw ggb, gbg, or bgg
and all those count towards ggb
try to calculate the probability of each those
they should all be the same
see if you notice why when you calculate them
i will brb
Green Green green - 3/9 * 2/8 * 1/7
Green green blue - 3/9 * 2/8 * 3/7
Green green red - 3/9 * 2/8 * 3/7
Red red red - 3/9 * 2/8 * 1/7
Red red blue - 3/9 * 2/8 * 3/7
Red red green - 3/9 * 2/8 * 3/7
Blue blue blue - 3/9 * 2/8 * 1/7
Blue blue red - 3/9 * 2/8 * 3/7
Blue blue green - 3/9 * 2/8 * 3/7
Green red blue - 3/9 * 3/8 * 3/7
i think
i have done it all
did you understand what i was saying here?
yeah
ggb is 3/9 * 2/8 * 3/7
gbg is 3/9 * 3/8 * 2/7
same thing
gives same result
yea
but
the probability of ggb (as in the probability of, with order, ggb, gbg, or bgg) is 3(3/9 * 2/8 * 3/7)
oh?
prob of ggb is (3/9 * 2/8 * 3/7), prob of gbg is (3/9 * 2/8 * 3/7), prob of bgg is (3/9 * 2/8 * 3/7)
yep
so you need to count how many arrangements there are for each combination
now i'm actually gonna brb
mmm alr
ill have a think about it and continue doing it, ill let you know if i need more help
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@near parrot Has your question been resolved?
<@&286206848099549185> 
do you have to use jensen
No, at least the exercise does not refer to it.
But I think that the study of the function in question one must be useful for something.
why is this so hard
just expand the inequality for a few small n and try to find a pattern
n=2, 3
Ok I'll try thanks
I have no idea how to prove it correctly
did you expand it for n=2 and 3
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,tex Let ( f: [0,1] \rightarrow \mathbb{R} ) be a function that is twice differentiable, and such that for all ( x \in [0,1] ), ( f''(x) \geq 1 ). Show that:
[ f(0) - 2f\left(\frac{1}{2}\right) + f(1) \geq \frac{1}{4} ]
Wakizashi
I have no idea how to start
,tex Since ( f''(x) > 0 ) for all ( x \in [0,1] ), it follows that ( f'(x) ) is increasing on this interval. Consequently, ( f(x) ) is convex on ([0,1]).
Wakizashi
Only thing that i know
Try integrating both sides of the inequality twice to get one including f(x)
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When we ask
Prove Something = something + O(some function)
Is it essentially equivalent to saying
Prove Something ≤ something + some function
why not consult the literal definition
to prove something one must assume something thy has already been proved and consult it how ever thy likes
The definition doens't make it clear
Definition simply says if f(n) is O(g(n)) then f(n) ≤ cg(n)
So what I figured is
eventually, yeah
Something = something + O(some function) is the same as saying Something - something ≤ c*(some function)
So we must simply prove Something ≤ something+ c*(some function)
?
I suppose that makes sense
Thanks
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Why is this wrong?
yea but what is wrong in my calculation?
the middle of the left side
@ocean hamlet Has your question been resolved?
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is this correct?
wait u shud be getting log|secx+tanx| +c
idk how u get it i just remeber the formula
yeah
maybe the 2 are equal
cuz i dont see any mistakes in my working
if there isnt i found a nice way to make a formula for tan^-1(z)
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Hi, can someone help me with this partial derivative.
what did you get
that's not right
you have a in the top and the bottom
or
it doesn't feel right
hmm
Any idea how should I begin?
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i got a bad result using law of sines to find A after finding b. a triangle solver online got the same result for b and B so i'm really confused as to why law of sines didn't work
c ~= 6.62 so sin(A) should ~= 11sin(35)/6.62
the online solver uses law of cosines instead and i can do that but i'm confused how this is wrong
how did you get c
c^2 = 11^+7^2 - (2*7*11)cos(35)
and just followed that down
ok wait
triangle calculator has the same result as me for that part and for angle B, but for A it gives a weird number
which, my calculation or the triangle solver?
triangle solver
nope, only the one
yeah?
real value also got me roughly the same weird result
i think it's because A is supposed to be the largest angle (since it's opposite of 11), but if you simply use law of sine you get around 72.32 degrees
agree?
did you get this for A
right
but
if u do 180-35-A for B, B>A
which shouldnt happen, as A is supposed to be the biggest angle
so that leaves us with the only other choice, 180-72.32 deg ~ 107.68 deg
that makes sense
you need to be very careful of what the other angles would be after you do law of sine
so if i used law of sines for all of them, is there any way to know which angle is wrong beyond running law of cosines on all of them?
hold on i think my textbook has this
i mean, A and B
well i guess like you said i can use 180 degree check on both and since i know a>b i know A>B
check if sin theta < 1, angle sum of triangle check
that's all i can think of rn
and the 180-x
there might be more
yeah
thanks a lot
really threw me for a loop there, i'm just now taking notes in this class for the first time and it definitely helps but i also definitely need to get better at it haha
you're welcome, you can always use law of cosines to double-check
yeah, i mostly just needed to know why sines didnt work
and i got it, thanks!
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we basically have to show that t_n>t_(n+1) which means its dicreasing which means its derivative is less then 0
i took the derivative and got
1/(n^2+2n+1) - 1/(n^2+n)
surely the denominator n^2+n is smaller than the other denominator so their difference gives a negative value thus the f' is negative hence dicreasing
is my method right?
because the solution did a little more complicated method
in the solution they integrated tn-tn+1 from 1 to infinity
and got the answer as somewhat 0.307
and then argued this
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$\lim_{x\to0}\frac{0}{x}$
Jash
its lim as x -> 0 0/x
you know that 0/x is defined except for x=0
What are your explanations for these two?
well i was gonna say indeterminate cuz when u do direct sub u get 0/0 which is indeterminate but if u evaluate the function first which is 0 and then put the limit u get 0
but oops helped me in dms so its fine
you can use l'hopitals as an option
or also think about it intuitively, the value of that expression is 0 for all x except at x = 0, so that includes any open interval containing 0 you could come up with, meaning that if you just think about delta epsilon stuff, you can make the value of the expression arbirarily close to 0 no matter how close to x = 0 you get
you can also think of it as a removable discontinuity
its basically the line y = 0 with a removable discontinuity at x = 0
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I need help with the following problem: A wholesale supplier of fertilizer has 3 types of garden fertilizer: the first type X with 5% nitrogen, of which 4000kg is in stock; the second type Y with 10% nitrogen, of which 1500kg is in stock; the third type Z with 20% nitrogen, of which 8000kg is in stock. There is an order for 1000kg of fertilizer that must have a nitrogen content of 15%. Therefore, the three types of fertilizer are mixed. Due to the stock, it is desired to use twice as much of type Z as type X. How many kilograms of each type should be mixed?
I can't find all of the equations.
I have 3x + y = 1000
And can't really find the other 2.
Maybe 0.05x + 0.10y + 0.2z = 0.15 but I'm not sure about that one.
I don’t see how you got this equation
This makes sense I believe
And you should also have 2z=x
Since you need two times the amount z as x
Yeah I tried to apply that to this one
Did it incorrectly though
Oh well that one equation you would only need two then
And yeah it makes sense that x+y+z=1000
Lemme put it in my calculator rq
So you have x+y+z=1000, 2z=x and 0.05x+0.1y+0.2z=0.15*1000
x+y+z= 1000, x-2z= 0 and 0.05x+0.1y+0.2z=0.15*1000 right??
Yeah
Seems right
3 equations 3 unknowns
Solve the matrix or use substitution or something
It's a conflicting system so I think somethings still wrong
Conflicting how so?
😦
I mean are you actually plugging in a 3x4 matrix and getting rref?
Or are you in a system of equations solver
Then what’s the resulting matrix
Please don’t ping
Mb
I see what you mean
I think that maybe removing z might help
Just putting it as 2x a
I got the right answer by indeed removing the Z and doing 3x + y = 1000
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its not exactly a problem per se but can someone explain this equation? like what does each thing mean
x_0 = x_i
x_f = x_i + delta x
.close thank you :)
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Solving this ODE with an integrating factor, did I mess something up
on symbolab it has a -1/2x^-2 instead of just x^-2
It's just a constant so it doesn't matter
You have C
-C/2 is still a constant
righhttt, so this is fine as is
i didnt think of it like that
thankyou
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help? using squeeze theorem
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do you know how to find intersections?
i think so
try setting up an equation for finding intersections
yes
@thin wraith Has your question been resolved?
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I have to solve for multiple equations on [0,2pi)
sec(x/2)=2 still 2 cycles?
i found 4 values 🤷
pi/3, 5pi/3, 7pi/3, 11pi/3
multiply by 2 to isolate x
2pi/3, 10pi/3, 14pi/3, 22pi/3
but 2pi/3 is the only one that fits in the parameters so is that my answer?
Yes.
Yes.
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how do I factor this??
x^2 + 5x - 6
6 + 1 = ?
Hello
Okay
Can you think of two numbers that multiply to -6 but add to +5?
-1 and 5 multiply to make -5
-1 6
there you go
yes
now what
(x-1) (x+6)
kk
I got
x^2 + 6x - x - 6
simplified its
x^2 + 5x -6
ok thanks
how about x^4 - 9
you can rewrite it as x^4 + 0x^2 - 9
we know the brackets to factor this is going to be (x^2 + A) (x^2 + B)
where A + B = 0 (the coefficient of the middle value, coefficient x^2 for this)
and A * B = -9 (the coefficient of x^0)
this should be a general guide on how to find it out for yourself, if u need help with using it i can help
you can just find it using trial and error to a certain degree, you just get better at seeing the correct numbers that fit in after some practice
0x^2 is the same as 0, they just didnt write it down because it's 0
im just writing it down for you so i can explain the concept of how to figure it out
it's a difference of two squares, if you know it by that name
the values A and B are so they add up to 0, and multiply to give -9
it's just one of the ways to find out the numbers
i can explain concept more if you'd like
this is the proof of the concept
so now you can use it to understand how to do this i hope
it's just something u give it a thought, in your head, what two numbers when added together give 0, and when multiplied by each other give -9?
ok im pretty much good
thank you alot for the help have a goodnight brother
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np and good luck 🫡
🫡
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I’m doing task 2117 and I’ve been stuck on it for a while
how are binary numbers less than 256 represented?
1 0 0 0 0 0 0 0 0
This is = to 256
The number furthest to the left must be 0 always
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Civil Service Pigeon
What does this tell me?
Yk how to read the notation right
Not really, I haven’t gone through it in class
Basically you take the number of numbers that satisfy each condition
And subtract the number that satisfy both (since this is counted twice - once for each individual condition)
Okey let me try
Binary system has 9 numbers and if the first digit is 1 it means it’s equal to 256
Then to have two digits as a 1 we have to take the combinations 1x1
Then we’re left with 9-3 = 6 digits that can either be a two or one
2^6
We can do that two times
And then I don’t know what to subtract with
Binary is 0s and 1s
But it’s clear that it’s at most 8 digits
So let’s consider it starting with two 1s
Consider how many numbers there are if there’s 3, 4, 5, …, 8 digits
You should notice a pattern
It’s it’s 3 digits and it start with two 1s you can have 2 combinations
4 digits gives 2x2 combinations
5 digits gives 2x2x2
6 digits give 2^4 etc
8 digits give 2^6 combinations no?
If we do that but with the last two digits we get 2^6 too
and if both two last digits and first digits are 1s
We get 2^4 combinations
Add that together I get 144 possible combinations and the wrong answer
That’s only for 8 digits
I’ll brb but see if you can figure it out now given this
Thanks for the help
Actually there’s a few issues here
You’re supposed to subtract the intersection, not add it
Read what I said earlier to see why this is true
And as I said, this is only for 8 digit numbers
So what about for 2,3,4,5,6,7 digits?
We don’t care about 234567
$111_2$ be like:
Civil Service Pigeon
Does it matter that there’s a text that says “ten” in the bottom right corner of 256?
Like the 2 is for 111 in the image above
Yes, you need to consider the binary representations up until that of $255_{10}$
Civil Service Pigeon
Yes and that’s 9 digits no?
256 base 10 is 100000000 in binary
So you consider everything less than that
Which is obviously any binary number with no more than 8 digits
Such as this
Yes right
So do you now see why you need to consider some binary numbers other than those with 8 digits
No
Either digit is either a 0 or a 1. If the two first digits are 1s, that leaves us 6 digits that can be either 0 or 1. That gives us a combination of (2^6) x 1 x 1
Does my example of 111_2 not mean anything
And if the last two digits of the 8 digits are two 1s you get the same thing
What does it mean explain
It satisfies the condition of starting (and ending) with two 1s.
And is not 8 digits.
Yes but I thought they asked for starting and endings 1s in the binary system
Don’t they?
01100000000011
Unless stated otherwise
You normally don’t consider leading zeros
Plus I can counter that
Consider 0000011111111_2 = 11111111_2 = 255
By your logic, this would fail
This satisfies to having starting/ending two 1s, it’s one of the combinations
Why would it fail
Explain in detail why 111_2 would fail by your logic.
So then why are you saying you don’t need to consider numbers other than those with 8 digits
When there’s clearly a counterexample
Unless you mean you can just shove 0s in front to make it 8 digits
But the method doesn’t account for that so
Take that as you will
You can write 111 with 8 digits in the binary system
Oh so that’s the issue
Well say that you have a 7 digit number you make 8 digits by shoving a zero in front
Then you have 011(…) where (…) is some string of 5 digits
Then there’s only 2^5 combinations, not 2^6.
Yes
But for 256 you have 8 digits to work with and the ninth digit is a leading 0
Then you have 2^6 combinations
It’s clear that whatever I’m saying isn’t being understood
So maybe just wait for someone else to explain
Original question for anyone who is interested:
We’re saying the same thing but you want to use 7 digits and work with 6 digits
Why’s that?
yk what
Let’s just do it like this
- Start with two 1s
I. No numbers after (11) -> 1 possibility
II. 1 number after (11) -> 2 possibilities
III. 2 numbers after (11) -> 2^2 = 4 possibilities
Yes
Continue to get 1+2+4+…+64=127
Same logic for ending with two 1s, you get 64
So we have 254 minus over count
I. Two digits (just 11) -> 1 case
II. Three digits (just 111) -> 1 case
III. Four digits (just 1111) -> 1 case
For k>4, if you have k digits in total, there’s (k-4) digits to fill in between the two ending strings, so 2^(k-4) cases
So you have 1+1+1+2+4+8+16=33 over counts
Take this as you will
I’m not engaging in this conversation anymore.
Okey thanks for the help 👍
254 - 33 still gives me the wrong answer
Is the answer sheet wrong?
Can someone explain to me why’s that
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How do I solve this?
volume of a sphere is $4/3 \pi r^3$
$\frac{4}{3} \pi r^3$
Kihei
🙂
swerriee
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YO WSG G
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Yo wsg
we need to evaluate the expression (1/1000)^1/3
Hey
Ok bro
WSG G
This time dont just give the answer
wha you need help with now?
Ur supposed to learn it
we need to evaluate the expression (1/1000)^1/3
what?
Really
are you helping rick or am i?
Ur not helping rick ur just gicing the answers
no im not?
ask rick
lol
he’s showing steps
he’s not
Ehat
yah?
Well if you did teach him
He would knoe, cuz this problem had the same steps as the last
oh it did
can u explain them