#help-13
1 messages · Page 272 of 1
...?
a. it'd been 5 minutes since you posted when you pinged us the first time
b. it'd been 13 minutes since you posted when you pinged us the second time
c. the factoid states both wait 15m and ping ONCE
*sighs*
ykw leave it
ok so are you the helper?
i help as per my discretion, sorry
and what does that mean?
...?
bro im new to this how do i get help
omg u were there the whole time waiting for it
(now again i cant help, this is one of my weak points so im sorry)
nah lol
BRUH
oh im sure they will
i give up on life
who said humans are better than ai
i will ask an ai
and if it gets it wrong, at least i didnt lose half my brain cells waiting
no no no dont do that
Please do not trust ChatGPT or similar AI tools for mathematical tasks, as they often generate output which "sounds correct" but has numerous factual or logical errors. Use of these AI tools to answer other people's help questions is strictly against server rules (see #rules).
@solemn fern Has your question been resolved?
Should Mhyd1427 wait for 30 mins and not get an answer tho😢
I squeezed my brain and google and wolfram alpha to get an approximation 66 square units
you're trying to calculate this?
it doesn't look very friendly
Really isnt
Even wolfram alpha had to approximate it
So this means that there was a mistake forming the integral
But its the only way it seems
the thing inside the square root is a perfect square
but i don't know how much that helps
$$x^8 + \frac{1}{2} + \frac{1}{16}x^{-8} = \left(x^4 + \frac{1}{4}x^{-4}\right)^2$$
Bungo
Or maybe the question is assessing my ability to form integrals and use approximation methods maybe?
possibly, what's the context, is this a calculus course or what
Yep it is calculus
I have the question posted i think here
Here
This was my attempt
@solemn fern Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
hi! thers a way to solve this limit using euler?
@burnt glacier Has your question been resolved?
@burnt glacier Has your question been resolved?
you mean by using euler constant?
umm i know the answer is going to contain the euler constant but theres a limit pattern that we can write as euler
this one
You can use the fact that $x$ can be written as $x = e^{\ln(x)}$
Alberto Z.
yes thats the solution , but i wanted to know if we can use this rule instead
Idk, it will be easier tu use x = e^lnx
It doesn't seem to easily apply here
@burnt glacier Has your question been resolved?
Is there any way we can do it?
Youre right. I know its not ideal but i would like to figure this out
I don't think so, or at least I can't figure it out
I would suggest using the most appropriate strategy for the question
Rather than trying to think you can apply one strategy to all of them
I agree
@burnt glacier Has your question been resolved?
i agree as well but my professor did somehow managed to solve it this way
i tried to solve as he did but i only made it halfway
this were i got stuck at
he started like this but from this point im kinda stuck
That's crazy
So he didn't take the logarithm of that
how can we pull this off from this point?
Fair, your question is going to be sitting for a while though
can you try it with this method?
there is initial mistake here, so I'm not going to continue that, since: (1+x)^1/x --> e, when x->0, and in your case, x - 1 does not go to zero when x ->0, clear?
this way, you can't solve it,
you need this:
but not what you wrote in your paper
to obtain the required result, I suggest you to use what I've written first
unless you figure out some sophisticated substitution of the variable
But thats what i did eventually
I “added zero” to the limit
/doubled it by 1
yes, but x - 1, must go to zero if x -->1
and in your case
x - 1 goes to -1
so you cant replace it with e
oh so it only works if x—/—>0 ?
your expression must go to zero,
not mandatory x
but all this expression behind 1
you see ?
x - 1, here, goes to zero
i understand what you wanted to do, sure, but in your case, it failed
do you know the oroginal answer ? if not i can tell you
then you can verify your calculations
@burnt glacier Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
any help here?
.close
Closed by @fresh loom
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
can someone explain wtf is happening here?
@naive ember Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
minor problem; they never taught us how to do questions where you need to find the line of intersection
I've got the cartesian equations for each
-4Xx1-3Xx2-5Xx3-7=0
3Xx1+5Xx2+x3+8=0
@raw yoke Has your question been resolved?
here's an example video https://www.youtube.com/watch?v=Q68F0Tr0-q8
We use Gaussian elimination to solve a system of equations that gives us the equation of a line that represents the intersection between 2 planes.
you want to eventually get to equations like x1= ... + ...*x3 and x2= ... + ...*x3
just have to cancel out some rows in a matrix first
Find the normal vectors of both planes using the cross product
Then the line of intersection must be normal to the two normal vectors you get
If you draw a diagram you can see why
Oh right once you get your line, sub x, y, z into ax + by + cz = d for any one of the planes
That's how you find a point the line passes through
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
i dont understand this,
im new to sin / cos stuff
if anyone could explain this, it would mean SO MUCH
this not trigonometry...
i don't see A and B
oh
why you doing calculus without trig knowledge
probably meant P and Q
i can tell the underpaid teacher energy just from that ss
lol
for P x is 0 because it's on y axis
okay
now plug in x=0 in y=x^2-4x+6
ye
so its 6
what's 6
no
oh okay
0, 6
yes!
yes
please talk in a singular or few sentences
okay sorry
yes
25 - 20 + 6 = 11 ?
y = 11 therefore, coordinates for q is (5 , 11)
yep
now do you know integration?
dy/dx etc ?
that's differentiation dear but ill be good if you know differentiation
shucks T.T
you don't know integration?
I just learnt it pretty sure..
or differentiation
good
what's a definite integral used for
um is it unique values
do you know how to integrate?
not really.. T.T
for example $\int x^n dx=\frac{x^{n+1}}{n+1}+C$
The Prophet Of The Damned
OH YEAH I KNOW THAT
when it goes to the opposite its like n-1 rightt?
Yeah so what's the integral of x^2?
I don't know what you mean here
same
sorry, maybe i got mixed up with a different topic for that
answer dis

plug x=2 into this
okay
bruh
sorry
you'll learn dw
what you get
yep
how did you know it is to plug n=2
now what's the integral of -4x
Cause when n = 2, x^n = x^2
because x^2 compare it with x^n n=2
Ah actually, what's the integral of x
Think about what the exponent is if you just have x
^0
I feel they need smaller steps than this
-4 factors out that's why
Nope, x^0 = 1
I know we'll get to that later
man
oh ya whatever^0 is 1
Yeah basically cause you have x^0 = x^(2 - 2) for example
= x^2 / x^2 = 1
You can have any other number instead of 2 and it will still cancel
kim why did you decide not to learn calc before trig
oh okayy
Okay so now what's the exponent of x
x=0
i dont know anything 
learn things in order dude
by the way, is this in O levels syllables?
huh
nevermind
answer this rn
don't get distracted
n?
O levels I think doesn't have integration
I need to check, anyways
Nope, x^n is just x^n
okay im not done for 😭
in regular ol' x he meant
the exponent of x^n is x^n 
oh, i dont quite understand that sorry
now answer
Honestly take your time
I don't understand this, i meant
what is the exponent of x in x^1
exponent of 1 equals to the base, so is it x
no x is in the exponent would mean x^x
OHHHH
if i say $x^n=x^1$ what is the value of $n$?
The Prophet Of The Damned
1
yes
so plug n=1 into #help-13 message
great
ask yourself this question
replace 1 with the power that's given
okay
may i now?
ok do you know an integral is a linear operator
Let's say the green function is f(x)
And the blue function is k * f(x)
So the area under the green function is the integral of f(x)
Too complicated, use simpler words
no .. 😭
definite integral
Yep yeah
Okay so what must the area under the blue function be?
id use my mother tongue for that
wait huh?
I should rephrase
If the green function is f(x) and the blue function is k * f(x)
How much larger is the area under the blue function compared to the green function?
by what factor
squared? :D .. sorry i dont know
Okay, so do you see that all we're doing to the shape under the function
yeah
We're just stretching that shape in the y-direction
And we're increasing it by a factor of k
k times larger
k is constant?
Yep k is a constant
If we have k, we mean it's a constant
Like if we have x, y, or z, we mean it's a variable
how can we tell which one it is?
You just have to read and get exposure to more maths
okay
It's like how you get better at understanding the events in a book or how characters develop if you read more
ooo yeah thats true
Yep
So because the integral is just the area under the graph
definite integral*
The integral of k f(x) dx = the area under k f(x) = k * the area under f(x) = k * the integral under f(x)
I know I'm simplifying things
$\int k f(x) \ dx = k \int f(x) \ dx$
south
You can have a variable such as x in your limits of integration
And it's still true
That's an indefinite integral since you will get a function of x, not a number
do you know sum rule for differentiation?
wait can this be explained in a simpler term?
What didn't you understand about that explanation?
i think we need a transaltor
no 😭 ..
No they just need things broken down into really small steps
You need patience
it was a joke chill
sorry, at what age do people learn this usually.
im 13 idk
im cooked
south is in uni
and asian
but in india it's 15-16
It's not about age actually
yes for real real
thats true
underage discord, sus
whenever 11th or 12th grade
Nah I mean your account was created in... yk
i turn 14 in may
🤫 🧏
Everyone has different talents
get back to topic
I suck at drawing
im not 😔 \
okay
The area under f(x) + g(x) is just the sum of very thin rectangles
And the height is f(x) + g(x) ofc
knowledge doesn't imply success in math
I'll pull up a picture
practice does
practice is a real one
Like these rectangles in practice would be so thin, their width would be pretty much 0
So the area would be exact
imma ignore the riemann sum on the right
Yeah like ignore the formula, it is relevant but like it's not worth going into
not rn
oh i see
but it's a jumpscare when limit of a sum
Yeah the height of these rectangles is going to be f(x) for the particular x value
If you let the rectangles have width almost-0
Then every x will have a rectangle corresponding to it
So the 'height' is just f(x)
And the width we call dx, dx stands for a very small number on the x-axis
okay
Yep, so if we use the same widths of the rectangles for f(x) and g(x)
Yes
The height of a function is just f(x) for that value of x
can you give an example question
Basically this explains why $\int f(x) + g(x) \ dx = \int f(x) \ dx + \int g(x) \ dx$
then explain the answer (u dont have to if its too yea)
south
The height of the function on the left is f(x) + g(x)
And the height of the right hand side is also f(x) + g(x)
And all the widths are the same
how do you tell
So the combined area of all the rectangles is the same -> the integrals are the same
We just make it happen that way
okay
You can always choose some points on the x-axis of f(x)
And make those points the same for g(x)
The assumption is that these are the areas from x = a to x = b, for both of them, sorry
this implies $\int af(x) + bg(x) \ dx = a\int f(x) \ dx +b\int g(x) \ dx$ when combined with the scaling example
The Prophet Of The Damned
Yeah, so $\int a f(x) + b g(x) \ dx = \int a f(x) \ dx + \int b g(x) \ dx = \cdots$
south
Combining the two rules together
Okay now we can do your question, the area of region A1 which is the region under the parabola
That's $\int x^2 - 4x + 6 \ dx = \int x^2 \ dx + \int -4x \ dx + \int 6 \ dx$
south
we're speedrunning calc 1
Using the f(x) + g(x) rule for 3 functions
Like (f(x) + g(x) + h(x)) = (f(x) + g(x)) + h(x), break it into 2 first
And then break it again
$= \int x^2 \ dx + (-4) \int x \ dx + 6 \int 1 \ dx$
south
Using the k f(x) scaling rule
$= \frac{x^3}{3} + (-4) \frac{x^2}{2} + 6x$ plus a constant
south
(We add a constant cause if you differentiate an integral, you get the original function back)
(So if you differentiate a constant, you get 0 and you get the original function back as well)
With me so far? This is a lot I know
well.
if im quite honest, ive never been taught these formulas
True
underpaid teacher alert
😭
We're almost there I promise: we can turn this into a number which tells us the area
this is the homerun
Now we can actually just sub x = 5 in, that gives us a number we can call A
And sub x = 0 in, that gives us a number we can call B
Then the integral from 0 to 5, or the area under the parabola is just B - A
it's year 11/12 stuff usually
oh i see
OH
Like I know we're subbing in individual numbers
But the area from x = 0 to x = 5
Is just (area from x = -1 to 5) - (area from x = -1 to 0)
Or (area from x = -10000 to 5) - (area from x = -100000 to 0)
You get the idea
what im getting is that A1 is the integral of the graph? so we plug x=5 in the equation and A2 is area under PQ - A1 ?
Yeah so A2 is the integral of the equation of the line - parabola
In other words, the area under the line, minus the area under the parabola
That's A2
okay
But actually, if you notice, the area under a line is just a trapezoid
can u highlight wheres the parabola
Let me scroll up
okay
Hopefully you can see this is true
we need slope for that
Yeah so of course the first thing would be to figure out the equation of the line
So that we can minus the parabola and get a function
handwriting is shit, sorry
delta x is 5-0
you can see its 5 units
now delta y would be the difference of the y coordinates of p and q
now remember what y coordinate of p and q are
(0,6) (5, 11)
so
6 and 11
5
so delta y is?
Or if you know the slope already, just tell us
is it 11/6 ?
no
wait 6/11
it would be the difference
oh i thought changes in Y = Y1/Y2
5 then?
yep
okay
what was delta x
5
is it wrong.........
Yeah I was saying the area under a line is a trapezoid
It's correct for when you have a line
nvm you got it champ
nah but looking at solution isnt
this is so stressful 😭
You need a break
Like honestly just come back to this tmw
And then you can practice more if you want to
No worries
@crimson sedge Has your question been resolved?
Closed by @exotic mortar
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
How do I tell whether the cross product of OA and OB is parallel to (1,-2,2,)
cross product of two vectors is the normal vector of the plane containing those 2 vectors
it doesnt make sense for a vector to br parallel to a point
If vectors u, v are parallel
then we can write u=kv where k is a scalar
@civic coral Has your question been resolved?
If you are asking about if 1i-2j+2k is a parallel to OA X OB then 1i-2j+2k=k(OA X OB) here k is a constant. In other terms if two vectors are parallel it means they are multiple of one-another.
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
in my signals and systems class, one TA uses such notation
$$
\langle f(t),g(t) \rangle = \int_{-\infty}^{\infty}f(t)g^*(t)dt
$$
Is this property/notation possible to use only in Hilbert spaces? I thought that this notation is used for inner product.
konxmok
also can somebody please help my understand, why is Hilber space so special? Why dont we use like some normal vector space. We touched it a bit in my quantum mech class but i dont se much why is it used (i dont have strong background in functional analysis since i study engineering)
well hilbert space is basically vector space + inner product
and yes thats precisely the notation for an inner product
(you also need that the space is complete)
but isnt inner product also defined on normal vector space?
and together with that inner product they are a hilbert space
also do you think that you may can point me to some literature that would help me understand the basics of spaces? I always had rather hard time with this topic and it will come handy for me
when we say something is a hilbert space, we say that it is a "normal" vector space and it has an inner product
basic of spaces?
oh okey
not sure what thats supposed to mean
sorry ofr the formulation, in lin alg we defined some abstract spaces, then here in physics and signals they throw hilbert spaces and i am just confused by the topics, so i thought that i will try to understand it more deeply (even when its not actually needed for any of my classes)
for vector spaces any linear algebra book should be good. for specifically banach/Hilbert spaces any functional analysis book should give some information
as we are engineers, they dont really "explain it", they just say that it works good f.e. in the Hilbert space
okey, thats what i thought, we have special non-mandatory class on functional analysis and measure theory, i will take it next year
also i have one more question, i have to calcuate correlation functio R12 of these two signals
I know the cor. func. is defined as
$$
R_{12}(\tau) = \langle s_1(t+\tau),s_2(\tau) \rangle =\int_{-\infty}^{\infty}s_1(t+\tau)s^*_2(t)dt
$$ but i am not really sure how to construct the integral with the tau shift, can somebody help me construct it? (i am able to calculate it, just not to costruct it)
konxmok
.close
Closed by @oblique lynx
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
i need help with upper and lower bounds theorem. i just learned that a polynomial can have multiple upper and lower bounds. when the question asks us the upper bound what we're supposed to tell?
like it makes 0 sense
i dont understand this theorem at all. i know this in general but everday i learn that i know smthn wrong abt this theorem
- how do i find the upper or lower bounds for a polynomial?
- also learned that the greatest value we find using rational root theorem is the upper bound and the lowest value we find is the lower bound. Is this True or False?
- i just learned that a polynomial can have multiple upper and lower bounds. when the question asks us the upper bound what we're supposed to tell?
- im so confused what this theorem even means. as i know upper bound mean we can have no roots greater than this and this works with the same (but in opposite) with the lower bound
these are my questions abt this theorem can someone pls hel me with these
wdym by multiple upper/lower bound?
i used a precalc calculator and it told me this
hold on
well if for example -10 is a lower bound, then clearly -20 also is a lower bound
its a "worse" bound, but its still a bound
okay i think i dont even know what does bound mean
okay pls lets start from the beginning im abt to go crazy bc i've been trying to finish this damn lesson for the past 6 days
and i have been trying to find the stupid bounds of a polynomial for the past 3 hours
what is this theorem
i dont get it
Do you mean the bounds of the roots of the polynomial?
im this close to quit math and major in social sciences and become unemployed fır the rest of my life
i dont know
well yeah i guess
idk what the question is even asking okay
it says
Find integers that are upper and lower bounds for the real zeros for the polynomial
i got
$$x^3-3x^2+4$$ and i found -1 as lower bound and 4 as upper
ates
i also got $$2x^3-3x^2-8x+12$$
ates
i have been trying to find the upper and lower bounds of this one for 3 hours
i keep finding that -6 and -12 is the lower bound
which one im supposed to give as an answer
i knew it but im so confused that i forgot whats even that
im not sure whether i know it correctly or not
Ok so consider a set A
If a real number p is greater than or equal to any elements of A
then p is a upper bound for A
then this means we got infinity numbers of upper bound?
yep
yeah technically 3552256783362 is an upper bound
butttt there's probably a specific answer they're looking for, maybe the lowest possible integer that works as one?
then we cant answer to the questions stating a specific upper/lower bound
oh
the lowest?
Yeah maybe they are asking for the lowest upper bound
how do i find upper bound or lower bound? I use rational root theorem usually but this time it didnt work for the second polynomial
$$2x^3-3x^2-8x+12$$
ates
this one
Can you show your work
alr wait a sec
here
12 is upper 6 is upper as well
so i just try each of these numbers and find the lowest ?
Maybe the question had specified
what is the original question
You can write any one of them in this case
okay so u see i wrote -1 as lower and 4 as upper
it says its incorrect
and it doesnt give answer to others
see
no 78
and the only one i did is incorrect
but -4 is also lowest here
like agh
-4 is the lowest lowest bound
Your answers are valid
it says -2
this is really weird
i think they're not i miscalculated them by putting 1 instead of 0
im redoing it and -4 is also a lowest bound
see?
i've been dealing with this for the past 6 days
once it says A is correct and on the next page it says A is incorrect
For 77, the roots are -1,2,2
So even though 3,-2 is a possible answer
4,-1 should also be correct
is -4 also correct?
for 77
also someone said the highest value we got when we're dealing with rational root theorem is the upper bound and the lowest value is the lowest bound
if you are talking about lower bound, yes
is this correct
yeah
i tried this and it works as well
so basically the highest value is the upper bound?
<@&286206848099549185>
What the problem
is the highest value we find using rrt the upper bound?
?
check out here
number 2
rrt as in rational root theorem
Ohh
@somber juniper Has your question been resolved?
.close
Closed by @somber juniper
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
i'm trying to draw something and my page is 24.6cm and that length is supposed to represent 31m
i can't for the life of me figure out how to divide the length of the paper into meters or whatever
so when i draw a point on my paper that's supposed to be say 1.3m, i want to know how many cm or mm that is
Only use 20 cm of the page, each cm represents 2 meters or something along those lines
Nws
@calm elm Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Anyoneee
!status
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
Sidenote, I wish my handwriting was as neat as yours lmao
I don't know where to begin.
Okie dokie, so do you know how to find extrema (maxima/minima) using the derivative?
yess yess
Okay, so how do we do that? ANd what do we get if we differentiate f(x)?
by using power rule igg
Yeah exactly, so give that a go and let me know what you get for f'(x)
its 2x - 5
Good, so what is 2x-5 equal to at a maximum/minimum?
umm dont know 😭
haha okay, so the rule is that your extrema are when f'(x) = 0
So 2x -5 = 0
So what's x?
5/2
Exactly, now they'll want it as a coordinate so we need to find the y value when x = 5/2
How do we do that?
by puting the value of x
Yeah you sub x back into f(x)
So what do we get for the y value when we sub x=5/2 in
0
TayBee
Don't substitute into f'(x) as we know that it equals 0 when x=5/2
Substitute it back into your original function, f(x)
ohh ok ok
maxima igg
What does a quadratic with a positive x^2 term look like?
ax^2+2x+c=0 ??
Yeah but I mean like if you draw it on a graph, what shape is it
u maybee
Yeah exactly a u
yess yess
So is the extreme point (at the bottom of th eu) a max or min\
can u send a picc i cant get it
Positive quadratic looks like that right?
So is the green dot the maximum or minimum value of the function
Origin is irrelevant here, it's the minimum - the line represents all the values the function can take right? So that green dot is the smallest value the function can ever take
This is your specific functiuon
yess yess so its absolute minimaa
Exactly
So that's the first question done, we have a minimum at (5/2, -1/4)
As a sidenote, we can also work out if something is a max or min with the second derivative, f''(x) - differentiate f(x) twice basically. Then substitute in the value you got for x when f'(x) = 0.
If f''(x) > 0 then it's a minimum and if f''(x) < 0 then it's a maximum.
But a quadratic is something we're all familiar with so I don't thinkkkk they would need you to do that here
If you did
f''(x) just equals 2
So it's always >0 therefore your extreme point is a minimum
But anyway
Part b
What do the words domain and range mean?
yess
The domain is basically asking the question of are there any values of x that would make f(x) undefined if you put it in
So like if you had a fraction, it would be undefinied if the denominator was equal to 0, or if you had a square root, it would be undefined if what was inside the square root was negative
But here
Are there any values of x you could put in that would cause a problem?
noo
Good, so our domain is just $x \in \mathbb{R}$
Latex has failed me
X is a real number lmao
Or alternatively (-infinity, +infinity)
Depending on how you've been taught to write domains
TayBee
There we go XD
And range is what we get out
So what possible values can y be?
Think back to what we worked out re. the minimum and what the graph looks like
2,1,0
So our minimum y value is -1/4 remember?
yess
But as you can see it can be anything higher than that
So y is any number that is greater than or equal to -1/4
Does that make sense?
ohh ok
TayBee
because if you look at the graph, the lowest y value we have is -0.25
And from there it just increases
yess
But it increases forever
To infinity
So that's our range
Does that make sense? Thats q b done lol
so infiity is our range ??
ohh ok ok
The range is just an inequality representing what values y can take
Using interval notation
You could write
[-0.25, +infinity)
ohh ok ok
So part c is just putting it all together
wait a min i will be right back
When you draw a function you should include
- x intercepts
- y intercepts
- extreme points/points of inflection
- asymptotes
- The general shape
Np
There are no asymptotes because it's just a quadratic, we know our extreme point (the minimum), we also know the general shape, so that's 3 4 and 5 done
All we now need to work out are the x and y intercepts
So how do we do that?
now we can put the values
Yeah, so our y intercept is when x=0 and our x intercepts are when y=0
So starting with the easy one, what's our y intercept?
-1/4
No that's our minimum
So we go back to our function
x^2 - 5x + 6
And we substitute in x=0
What do we get if we do that?
$y = 0^2 -5(0) + 6 = 0 - 0 + 6$
TayBee
What is 0-0+6 XD
hmm?
On your calculator, 0^2 - 5(0) + 6
Should just give you 6
So that's our y intercept
yes yess
You can see it labelled here
So now for our x intercepts
We substitute in y=0
$x^2 -5x + 6 = 0$
TayBee
So solve that, and what values do we get for x
its 0
Nope
Factorise the quadratic or use the quadratic formula
Or use the solver on your calculator if that's allowed lmao
-2
(x-2) is one of the brackets but that gives x=2 which you've already found
What's the other one
What two numbers multiply to +6 and add to -5
2 times 3?
-2 times -3
So your two brackets are (x-2)(x-3)
Which means x-2 = 0 or x-3 =0
So x = 2 or?
x=3

So there's are your two x intercepts
(2,0) and (3,0)
So label everything on your graph and that's the question done
Good work haha
@tired delta Has your question been resolved?
Closed by @tired delta
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
A symmetric matrix $A$ is called positive definite if $0 < x^T Ax$.
\textbf{Lemma 6.37}
For a symmetric matrix $A$ of size $k \times k$, the following statements are equivalent:
\begin{enumerate}
\item $A$ is positive definite.
\item All eigenvalues are positive.
\item There exists a constant $C > 0$ such that $C \cdot \lVert x \rVert^2 \leq x^T Ax$ for all $x \in \mathbb{R}^k$.
\end{enumerate}
\textbf{Proof:}
First we show that (1) $\implies$ (2).
$\lambda \cdot \lVert v \rVert^2 = \lambda v^T v$ and $\lambda v^T v = v^T A v$ and $\lambda v^T v = v^T A v$.
Why is this true?
// 1800
Recall that $||v||^2 = v \cdot v = v^T v$
south
You're just writing the first v as a row vector v^T
why is v*v = v^t v
And then $\lambda v^T v = v^T \lambda v = v^T A v$
south
If v = [v1 v2 ... vn]^T
Then the first entry of the row vector v^T is v1, which gets multiplied by the first entry v1 in the column vector
Similarly you get v2 * v2
So it's v1 * v1 + v2 * v2 + ... + vn * vn
so
dot product of v is v*v = v_1^2,v2^2,v3^3 etc
The dot product gives you a number, a scalar
So it's just v_1^2 + v_2^2 + ... + v_n^2
Cool
$|v| = \sqrt{v_1^2 + v_2^2 + \ldots + v_n^2}$. Squaring both sides of this equation gives us $|v|^2 = v_1^2 + v_2^2 + \ldots + v_n^2$.
// 1800
And yes, this is correct
and the dot product of v with itself is equal to the v^t dot v?
This
yeah
So lambda is just a constant: we can order it anywhere
how does lambda turn in A
By definition, lambda v = A v if lambda is the eigenvalue of the matrix A
It's a definition
ok
So if $Av = \lambda v = \lambda I v$, multiplying by the identity matrix which does nothing
south
$Av - \lambda I v = 0 \implies (A - \lambda I) v = 0$
south
See where that comes from now?
so what is the definition of lambda
lambda is the special constant
Such that lambda v = matrix A multiplied by vector v
And v is a special vector such that when you multiply it by matrix A, all it does is scale the vector along a line
And it doesn't move it away from that line
A visual understanding of eigenvectors, eigenvalues, and the usefulness of an eigenbasis.
Help fund future projects: https://www.patreon.com/3blue1brown
An equally valuable form of support is to simply share some of the videos.
Home page: https://www.3blue1brown.com
Full series: https://3b1b.co/eola
Future series like this are funded by the co...
@summer lintel Has your question been resolved?
Closed by @summer lintel
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Then what is gamma and how to find
So it's 124
is alr
?
If you are done with this channel, please mark your problem as solved by typing .close
@split egret
Closed by @split egret
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
I know the power reducing formula for cos^2x: 1+cos2x/2
do the 2's turn into 3's for cubed?
1+cos3x/3
hm, maybe I missed something in the book then. Dont recall seeing this, but I have a example for sin^4x. 🤔
Do you just have to remember each formula individually or is there a conversion for squard to another power?
I just google it
If only I could google during test 😅
well cos^3=cos*cos^2 so you could use the one for ^2 twice
would take longer obviously
combined with double angle
easier to just remember
Not sure im understanding. wouldn't doing it power reducing for ^2 be for ^4?
would you do the power reducing for cos^2x then multiply the result by cosx?
yes but then you have cosx*cos(2x) and then other stuff you have to worry about
Still not sure what im supposed to be doing then
Not even sure why this is on the practice test based on what Im reading about it
.close
Closed by @fathom star
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Need help with this
!status
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
@modern prism Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
@sand meadow Has your question been resolved?
@sand meadow Has your question been resolved?
Closed by @sand meadow
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Pyramid SABCD base - rhombus. The length of the rhombus side is 15 cm, and the length of the larger diagonal is 24 cm. The side walls of the pyramid form an angle equal to 45 degrees with the base (Which is a rhombus). Prove that OE = 7.2cm (O - Base center, E base edge center)
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
try drawing it out first
I have the drawing it was given with the task
but its in another language so i didnt do a photo, i rewrote it
send anyway