#help-13
1 messages · Page 165 of 1
so what we do is we interview a few random students and find the mean number for that random number. But we don't know if the mean we got is exactly equal to the mean for all students. But we can find a margin of error, which says it's likely the mean for all students is within that margin of error above or below the mean we got
so it might be up to 3 dramas more or it might be up to 3 dramas less than 15 and still be "inside" the margin of error
Wait whats margin of error?
Is it like, the dot that are not on the line of best fit?
when we use the sample to estimate something about everyone we think the mean for the whole population is pretty close to the one we got, but it may not be exactly equal
we say something has a margin of error of 3 if we think the "real" value is somewhere between 3 points above and 3 points below our estimate
the margin of error is just for estimating the average. it doesn't tell us how close any individual student might be to the average
But it does tells the number that are not on the line of best fit righth?
C is wrong for sure
But B seems the most correct
remember, we're trying to find the average number of dramas watched by all students, without asking every single student. We know it's probably close to 15, since that was the average we calculated from the students that we did ask. But it might not be exactly 15, which is why we have the margin of error
So its either A or D? Because it aaid between 12-18
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D maybe C
no c is possible nvm
A doesn’t list population so…
is the population 5, 20, 1000?
Question?
nah i was just looking at the last one
@quasi plover
im interested
what was the answer here?
because A looks plausible (i dont remember standard deviation rn)
wait A should be like 68% and true
but D should definitely be true
@oblique raven Has your question been resolved?
No clue
That dude never answer me
Question A and D looks fairly similar
I dont even know the diff between those 2
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hello everyone
@dim tiger Has your question been resolved?
the angle between $\hat{\phi}(t_1)$ and $\hat{\phi}(t_2)$ is $\Delta\hat{\phi}$
calculus is fun
no this is not the reason because $\frac{d\hat{r}}{dt} = \dot{\phi}\hat{\phi}$
calculus is fun
do you mean $\Delta\phi$ is reducing ??
calculus is fun
because $\phi$ is not necessarily reducing
calculus is fun
how is the direction of $\frac{d\hat{\vec\phi}}{dt}$ opposite to the direction of $\hat{\vec{r}}$
calculus is fun
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In a group of 30 people, 10 play football (A), 5 play basketball (B), 2 people play both
find $p(A) p(B) p(A\capB) p(A\cupB)$
紅卫兵
Compile Error! Click the
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Well, i just checked. \cap seems correct. Lol
For intersection.
$p(A) p(B) p(A\capB) p(A\capB)$
\frac{\dd {expression}}{\dd {x}}
missing spaces
$\frac{\dd {expression}}{\dd {x}}$
Enemagneto
oh so frac must be used
$p(A) p(B) p(A\cap B) p(A\cup B)$
thanks
Ann
@simple bane so you want to find the product of these 4 probabilities?
yes
At least, i do. Others might know a better way.
i know p(A) and p(B) but i don't have any idea how to solve the intersection and union
if football is A, then it would be 10/30
what is the difference between the "product" and "each one individually"?
product means you're multiplying them all together and report one number
each one individually means you don't multiply them together, and report four numbers
can we do both?
yes
and you also got that p(B) = 5/30
so what's p(A n B)?
you are told how many people play both games
2
TAX
should i draw Venn diagram?
not yet
you know the number of ppl who play both games is 2
p(A n B) can be figured out the exact same way you did the prev two
should i use this formula?
no, not yet
again
you had no trouble going from |A| = 10 to P(A) = 10/30
do the same thing here for P(A n B)
you know |A n B| = 2
2/30?
so is 1/15 correct?
P(A u B) = 13/30
show your textbook's answers.
also show the problem as it was written in the textbook.
Sorry, my first language is not english so i don't think you will be able to understand.
send it anyway.
i speak a few languages other than english.
standard procedure for problems written in foreign languages is to send them anyway, and provide a translation if somebody asks.
ok i thought the language might have been chinese
but i was thankfully wrong about that
lol
i think the way they did it is a little strange, and also for some reason they're rounding everything to the nearest 0.01 while we had exact answers all along
oh also another thing
it looks like you might have lied about the goal of the problem
well the things they're calculating aren't the same as the ones you mentioned at the start
they don't calculate P(A) and they don't calculate P(B) and they don't calculate P(A u B)
i just wanted to "warm up"
hjkdsjflh
and then you cry "OH BUT THE ANSWERS ARE DIFFERENT"
when you yourself ask for different things than the textbook
.-.
wait
also $P(A \cap B) = P(A) P(B|A)$ is true, yes. but imo very excessive here.
Ann
what is imo?
in my opinion
so i just memorised a bunch of formulas, and didn't really thoroughly understand them
so 🥲
and how come it's excessive to use that formula
Pleas don't leave me. I am very sorry for everything i have done
it involves more computation and concepts than necessary
like, if you can calculate P(B|A) as 2/5, then why not calculate P(A&B) as 2/30 in the first place?
no they aren't the same.
also do you mean "what's the number for P(B|A) here?" or "what is the meaning of P(B|A) anyway?"
the value of P(B|A) here is 2/5
P(B|A) is the probability that B happens given A
informally, what fraction of scenarios where A happens are also part of B?
i didn't catch that
P(B) is what fraction of our group are basketball players
P(B|A) is what fraction of the footballers are basketball players
Thank you for the help, i will work on this later 🙂
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$a^x * b^x$
marty
No...
marty
Compile Error! Click the
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||a^x × b^x = (ab)^x||
but isn't the rules of powers saying to add the powers? 1 + 1 ?
right okay, so when bases are not same, exponent remains similar
and if both bases and exponents are different, we can do no further simplification, e.g:
$a^x * b^y = a^x * b^y$
marty
Ye...
||a^x * b^x = (ab)^x (not sure why you said equal or superior)||
Typo
I meant to says implies
There you tl
*go
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does anyone know what it means when it says to tell the values of 𝜃 for which the graph would be drawn once, and only once? i know someone already talked about it but i am still kind of confused
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a or d?
someone posted this earlier
B is straight wrong
and we dont have populations,
so C is wrong
Probably D, since there could be some outliers
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i just don't understand
they didn't multiply by the inverse squareroot
they brought it down to the denominator
😦
so sqrt(x)^2 = x, and this other sqrt(x) is from that inverse sqrt(x)
then the first term is sqrt(x) * 1
i no longer understand how simply multiplication works apparently anymore after starting to do derivations but
how do i start on the second term
yeah
second term
imagine the inverse square root just went down and all that's left is (2 sqrt(x) -4) * 1/2
hold on
?
what is even the second term
is it all after the negative sign
$-(2sqrt(x)+4)\frac{1}{2sqrt(x)}$
marty
yeah
okay
marty
noo
the reason why they could bring it to the denominator is because 1/(sqrt(x)) is a common factor of both terms
the denominator now is just $x*sqrt(x)$
lotus man
lost
it is (sqrt(x))^2 to begin with, which equals x, we bring down one inverse square root, so we have x * sqrt(x). Why would we not add 2sqrt(x) if we bring them down too?
.
there are 2 terms in the numerator
we can factor them by the inverse square root
@keen nova Do you understand this part so far?
The sqrt(x) * 1/sqrt(x) cancels to be one
Then I multiplied the 1/(2sqrt(x)) into the parentheses
hold on, so we solve the first term, i get that, then solve the second term. Okay, understandable. And we didnt put any inverse square roots down to the denominator
No not yet
that makes more sense to me
okay from here, first term of right term cancels = 1, second term 4, we dont add it i think?
oh wait
hold on
And (sqrt(x))^2 = x
okay so we can divide 4 and 2sqrt(x) both by 2
i wasnt sure if we could do this
so thats 2 over sqrt(x)
yes okay i am with you so far
and now, can you omit the parenthesis? i dont see it
what to do
Then this simplifies to
Then what you can do is multiply the numerator and denominator by sqrt(x)
okay, thats okay, but how do you get -2 over sqrt(x)
From here
That -(1 + 2/sqrt(x)) becomes -1 - 2/sqrt(x)
And 1 - 1 = 0
i cannot see it
-(a + b) = -a - b
That's what you can do here
Distribute that negative
To get this
-(1 + 2/sqrt(x)) becomes -1 - 2/sqrt(x)
okay so i see what u did. But hold on a second
lemme just go back to my calculations
my second term i had
can i ask one question about this
$(\frac{1}{2sqrt(x)}) * (2*sqrt(x)+4)$
marty
Multiply that 1/(2sqrt(x)) into the stuff in the parentheses
So a(b + c) = ab + ac
which solver did you use for this btw
or was it given in your assignment solutions
OMPT-D
so this?
or is it a solver which solves equations
and operators
do you mean the first term, or the first factor of this second term
i was asking this cause the steps are crazy
.
cant we just do this
You can treat $\frac{1}{2\sqrt{x}}$ as a so then it's $a(2\sqrt{x} + 4) = a \cdot 2\sqrt{x} + a \cdot 4$, plug back in a
dldh06
okay i see
wait is it? whats the question
So then it's $\frac{1}{2\sqrt{x}} \cdot 2\sqrt{x} + 4 \cdot \frac{1}{2\sqrt{x}}$
dldh06
nvm he is helping , and understands i will just go , i dont want to create more confusioon
sorry
okay i see although i would swap order of factors for the second term
but obv ye i see
Then the 2sqrt(x) cancels in the first part to be 1
The second part becomes 2/sqrt(x)
Like what I showed here
okay so now the entire second term is split up like that. Hold on a second now. Should the terms be separated by parenthesis each, or in one full parenthesis (or rather no parenthesis)
It doesn't matter because of order of operations
$(\frac{1}{2sqrt(x)} * 2sqrt(x)) + (4* \frac{1}{2sqrt(x)})$
marty
.
so when doing factoring, it will never matter
?
i'm trying to understand when i need to apply parenthesis in general
because i have made a thousand such mistakes today
like let's step back one second. I think I understand where to go from there you showed me
but this is the whole process:
quotient rule: I lay out g(x) and h(x)
i take their derivatives each
Take in consideration of PEMDAS
now I do g'(x) * h(x) - h'(x) * g(x) / h(x)^2 (quotient rule)
The parentheses are redundant as multiplication would be next
so i put in these functions, and their derivatives in the formula like this
i put a parenthesis around EACH of these. So 4 parentheses in total
am i thinking correct so far.
If it helps you understand the problem better, you can do that
$(g'(x)) * (h(x)) - (h'(x)) * (g(x))$
marty
It might make it overwhelming with that amount of parentheses if you do it that way but it works
okay, then the right term is a good example. Here we end up with this:
.
we make it into this
Yes
woops i mean this
Both this
And this are the same
right they're the same
i see now
but okay
now to be clear
there are no longer any considerations of parentheses
it is strictly order of operations
across the entire nominator
Pretty much
i'm struggling to imagine where exactly parentheses are needed
but i know sometimes they matter
in this case i think they dont
if im gonna be able to solve these problems i need to know this
If you had $2+ \frac{1}{2\sqrt{x}} \cdot 2\sqrt{x} + 4 \cdot \frac{1}{2\sqrt{x}}$ then parentheses would need to taken in consideration due to distribution
$$(2+ \frac{1}{2\sqrt{x}}) \cdot 2\sqrt{x} + 4 \cdot \frac{1}{2\sqrt{x}}$$ and what is shown above are two different statements because 2sqrt(x) would get distributed on the second expression but in the first, it does not get distributed
dldh06
okay yeah. So because 2+1/2sqrt(x) is a term, and we want to distribute it, it needs to be in parenthesis
so relating to the quotient rule
$(g'(x)) * (h(x)) - (h'(x)) * (g(x))$
marty
we don't want to distribute the negative across the entire second term
is that correct?
Because you're not distributing anything, you don't need to surround each term with parentheses
You can but I did it later
but hold on here we wouldn't even distribute would we
This step
To this
You do need parentheses surrounded everything though, because of the negative sign outside
If you look at this image
There's still that negative on the outside
so the second term needs to be respected as a negative term
and that would distribute the negative within
at one point at least
Yes
and this is true for all formulas or rules or whatever
since this is the definition of the quotient rule
And because the negative would get distributed, that's why you need parentheses
but i thought the quotient rule wasn't even defined like that
g'(x) * h(x) - h'(x) * g(x)
we're not saying
gh(x) - hx(x)
Notice here how you have the negative outside 2sqrt(x) + 4
it's not enclosed as a function
You can distribute that negative first into 2sqrt(x) + 4
But I didn't
I multiplied 2sqrt(x) + 4 by 1/(2sqrt(x)) first
Because multiplication is commutative
You could have done -(2sqrt(x) + 4) = -2sqrt(x) - 4 first if you wanted
marty
No
with negative sign
Because it's not $-\left((2\sqrt{x}+4)\frac{1}{2\sqrt{x}}+6\right)$
dldh06
you have two functions
only the first function is in contact with the negative sign
only that function should be distributed with negative sign
not the entire term
correct ?
No it depends on the parentheses
Whether it's this, this means all the terms the negative gets distributed to
i understand that
Or this where only the first term gets the negative
i'm asking if the parenthesis should be inserted in this example
because we're inserting two functions into the formula, the quotient rule
should we treat the term as having parenthesis
This example meaning the original problem?
i mean in general for the quotient rule, but also any formula that might be used, i guess
i think the parenthesis should only be considered around the functions each
so 4 paranthesis in total for the quotient rule
No because as I mentioned it's based on distribution
This is quotient rule here
yes
there i see 4 parenthesis
well not really
but
imagine one around each function
i mean
surely it has to be either that we put parentheses around the terms, OR around the functions inserted
or else it should mean we don't put parenthese at all?
either
$(a) - (b)$
or
marty
$(f1) * (f2) - (g1) * (g2)$
marty
I think you are just confusing yourself even more
i don't think so, cus i've been getting almost exclusively wrong answers using the quotient rule so far
i'm obv confused lol but
i def don't get it yet
https://www.youtube.com/watch?v=8jVDEcQ0wXk&ab_channel=TheOrganicChemistryTutor
Trying watching this and doing the examples with the video
This calculus video tutorial provides a basic introduction into the quotient rule for derivatives. It explains how to find the derivatives of fractions and rational functions. It contains plenty of examples and practice problems.
Calculus 1 Review:
https://www.video-tutor.net/calculus-1-review-basic-introduction.html
I like this channel v much btw, been using it for everything so far
3 min in, and it seems like he puts parantheses arounds the functions
this helps distribute correctly
and also means that only the first function of the second term has the negative sign
Yeah, like I said parentheses are used to based on what gets distributed
my mind is v slow rn but... isn't it also opposite?
what gets distributed is based on the parantheses?
we put parantheses around the functions thus we distribute this way
i should have just watched this video to begin with
and so
after this distribution, between : f1g1 and f2g2
we no longer have to consider any parentheses
i think we clarified this at the beginning
so sometimes we need to distribute. That is based on what parantheses are set up. Functions are naturally put in parantheses. After distribution, order of operations rule
Yes
If that is all you have, feel free to close this channel and come back if you need more help, otherwise good luck
okay, i followed these principles, redid the exercise, and got it right
i think i get it now
thank you so much
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i've gotten so lost while doing my integral
stiroy
ok yes keep going
then i write $ln(|1+sin(pi/6)|)+ln(|1+sin(-pi/6)|) = ln(3/2) + ln(|1/2|)$
stiroy
it's F(top) - F(bottom) not plus
so it should be ln(1)?
how's that
well if i rewrite it, i get ln(3/2) - ln(|1/2|)
Hayley
I think he's talking about this
$\int_{a}^{b}f\left(x\right)dx=\left|F\left(x\right)\right|_{a}^{b}=F\left(b\right)-F\left(a\right)$
LE SSERAFIM
i messed up the quotient rule
Oh sry nvm
dw, i did mess that one up to after playing around with it soo much
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Determine all solutions to the equation sin x = 0.6 in the interval 0° ≤ x ≤ 450°
I mean, it wants x to be in the interval [0,450]
and one of your solutions is 756.87
so that doesn't quite seem right
you've found additional solutions by adding 360, which is fine
K = 0,1,2
but you're missing a few from symmetries
How do I go on from there?
so, the two solutions 36 and 396 are fine
but recall that sin has horizontal symmetry at x=90
try drawing a diagram
that might be helpful
there's a third solution you're missing though
you have the first and last intersection
but notice that sin cuts the line y=0.6 again between those two points
the black line is a line of symmetry
so we can reflect the x=36.87 solution across
the third one that is ≈ 143
(90 - 36,87) + 0 * 360 = 53,13
But that's still not correct
it's not 90 - 36.87
but you've almost got it
so,
this distance here
we want to add it to 90
to get to x3
but this distance isn't 36.87
the distance on the left from 0 to x1 is 36.87
probably an easier way to think about it is to look at the line x=180
these distances are equal, because it's symmetric across x=90
wait so does it become 180
the black line on the right is x=180
so 180 - 2 * 36,87
not 2*
just 180-36.87
x1 is 36.87 to the right of 0, so x3 is 36.87 to the left of 180
but don't we need to substract from the right (the blue right arrow)
Ok ok
I got it
yeah, the two blue arrows are equal in length
that looks right, yep
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why
@short blade
they are the same yes
so why....
did it say you were wrong?
Commutative property
noo... i guess not.. but i suspect that i got wrong answers on my quotient rule exercises when distributing
so i checked what was the real answer to the distribution
but surely its the same
yes those are the same
you could show your work for your exercise though and we can double check it
this is why they're the same, not why it's that's the result on wolfram alpha, right
if you got 1 min let me re'do it and i will show you, especially if im wrong
first i did this and then i put the 2 in front of the x, and that was wrong, idk why i did that, but now it's right
i guess i was just sloppy
did someone call me
could i further simply another way
I don't think so
another q
derivative of sin(4x)
chain rule because of 4x?
in other words is it cos(4x) * 4?
nvm i just checked it is
ok i have a proper question
regarding these steps. Was the division of 5x possible only because I divided both terms on the nominator as well as the denominator?
@keen nova Has your question been resolved?
@keen nova Has your question been resolved?
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I've done the product rule, as well as chain rule for right term of f(x). How can I simplify this
could factor out x^2 * 4^(x^5)
btw your notation is bad
you wrote g(x^3) when you meant g(x):=x^3, likewise you should have h(x):=4^(x^5) and not h(4^(x^5))
oh yeah i know
and f'(x^3 * 4^(x^5)) should instead be [x^3 * 4^(x^5)]', xor f(x) = x^3 * 4^(x^5); f'(x) = ?
im a lil tired today
if you know then don't write bad notation tired or not
i was going to omit parentheses
for those
its not meant to be the actual function definition
i just enclosed it in parentheses dont worry bout it
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@inner quartz
yo
ayo
who was it
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Yes, we know.
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✅
Ohok continue
thanks!
Okay! ill be around if you need math help
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Someone check this please?
the graph seems to match the words
The graph is already set by the assignment btw
The question (image 1) is based on the pre made graph
i guess my main thing is pay close attention to the graph spacing
are you saying I did it correctly?
i'd say almost? look at where the vertex is vertically
what does each gridline represent? lok at the axis
(this is probably not that big of a deal because you're just estimating anyway)
It represents throwing something in the air and how long it takes to fall(?) (the graph)
Mm ok
the point is that to me the vertex looks like it's at 25 rather than 24.25 
but it's nbd
I think the x of 1.25 would still stand or no?
I’m just gonna submit it
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Having trouble to solve part D, why does the E(x) has to be equals to -0.2P?
I see, thanks so much
They somehow got E(x) = 0.8P which is approximately right, but still not exact
$7.33 is the correct answer
For this question, the expected value is for the player, so in the organiser’s perspective, the expected amount of will be negative ?
For example, expected value for the player is $6.11
For the organiser, they will expect to lose $6.11. (Without any charges)?
Wait, no I am lying to you
Let P be what Ravi charges.
Then, 0.8P = E(x)
That's their third line
That is, 80% of what Ravi charges, he should expect to give back. That way, he gets to keep 20% of it
I don't know why they did the first line the way they did, since -0.2P is not equal to E(x)
I see, but I think by understanding the third line would be enough to solve the question
@random heart Has your question been resolved?
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can some1 explain
ill show the answer too
i understand the summation part
but how does that equal
the summation under them
this one
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why is dS equal to that
?
<@&286206848099549185>
??????????????????????
<@&268886789983436800> he is trolling
@molten magnet stop
?
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Closed by @bronze pivot
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i can help
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is this a surface integral
yeah
we're not there yet
cal 3
it's just how it is
right?
wdym
that is called the surface element
vecot projectioons
yeah
so whats the question?
I believe there are some derivative for it online? But that's just how it's defined. The surface element for a given parameterics of r(u,v) is the magnitude of the cross product of it's two gradients
THAS CORRECT
sorry
caps
mc
fb
why so many trolls
so in a similar way, if you have a surface represented by g(x,y), that could be expressed as the parametrics r(x,y)=(x,y,g(x,y)). To which the surface element is the one given in your picutre
wdym
this is the same thing as the Jacobian right waler
well no, the jacobian bares a different meaning
<@&268886789983436800>
(x,y,g(x,y)) is familiar though
okay i guess I just gotta remember dS = the magnitude of the cross product of the surface's two gradients
please stop posting in this channel if you have nothing to contribute
remember that the cross product just gives the area of a parallelogram spanned by two vectors, so this should make geometric sense
the two derivatives just give two vectors tangent to the surface

This is not the place to ask for help. If you want help, then open another channel. This is someone else's.
no thats not what im saying
im trying to aid him
sense i have some knowlegde on the topic
i wanted to see
what he was doing
You haven't said a single word to aid them yet, so please just stop posting in the channel
and try it myself
I block him
im looking at the problem ma'mm
sorry
ill leave
Okay anyways, LeGM does this geometric explanation make sense
yeah
cool :)
wait where did the +1 come from
basically you can parameterize the surface as <x, y, z(x,y)> and then the derivative in the x direction is <1, 0, dz/dx> and the derivative in the y direction is <0, 1, dz/dy>
taking the cross product of these gives you
<-dz/dx, -dz/dy, 1>
and then the magnitude of that is
ohh
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you're welcome!
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can anyone explain why 0.5x still negative and and where's the 1x.?
1x - 0.5x = ?
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Why is multiplication for formal power series defined by convolution 
because you can’t foil
(1 + x + x^2 + x^3 ….)(1 + x + x^2 + x^3 …)
You can’t just say that the result is 1 + x + x^2 + x^3 … + x + x^2 + x^3 … + x^2 + x^3 + x^4 + …
instead you take all the terms of a certain degree and put those first
I laughed
@crimson sedge Has your question been resolved?
this is a good way to understand convolutions tbh
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.coose
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Does it matter what variable i use for the bounds of an integral as long as i get the same answer?
I dont have the question but i did a trial CSSA 2023 and i got my marks back and i lost a mark for using x as a bound value instead of t but i got the same answer as the criteria
if it's an integral dx
i havent been given the paper due to securityy release dates
then you can't use x (in the limits)
its notdx
its dt
the equation required to integrate was in terms of t and i used x as my bound but my teacher argues that i lost a mark due as i should have apparently used t instead of x
if it's an integral dt then you shouldn't use t in the bounds
(with one exception which is the Leibniz multiple integration formula but I'm sure you weren't doing that)
for some reason my teacher thinks i needed to use t not x
I think we're confusing bound as in bound variable and integral bound
yyeah it was 2u
i can write an example if u want
the bound variable can be whatever as long as it isn't used before
yes please
if you just replaced all t's with x's, that should be fine
as i integrated in the exam i subbed in x and continued to solve for x and get a value in minutes which i also wrote with units
can u explain why so i can say it to my teacher
I mean, it's kind of a matter of scoping: the t only exists inside the integral
it's the same problem as using any other variable twice but with different meanings
i see
also
u know how the intergral isnt from 0
and if the question asked i.e the time required to accumlate a specific area you would do the upper bound - lower bound
and say that is the net time from the lower bound
yes, that's how you would evaluate that integral
Closed by @azure marsh
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how do you answer questions like this? A knife has a blade that is 31.3 mm wide and 2.02 mm thick. If it takes 1.39 lb of force to cut into a ribeye steak and you apply 0.237 lb of force on the knife, what is the efficiency of the blade? Answer in percent, and round your answer to 2 decimal places.
to answer questions like this, start from what they’re asking for
then find the relevant formulas for that quantity
which in this case is efficency
and do you know how to calculate efficiency?
output/input
Can you use that here?
yes but it gives the incorrect asnwer
What is the correct answer?
here is an example question i have the answer for
it is similar
A knife has a blade that is 33.7 mm wide and 2.40 mm thick. If it takes 1.25 lb of force to cut into a ribeye steak and you apply 0.239 lb of force on the knife, what is the efficiency of the blade? Answer in percent, and round your answer to 2 decimal places.
and
the answer is 37.25
so i am a bit lost
does the question give any explanation
no further explanation than that unfortuantely
has your teacher explained why
no he has not
not that i asked him
because we have open tutorials and i hadnt come across this question
until now
we have no lectures
i am not majoring in math its just a course I am required to take
i am actually quite bad at it lol
its definitely a weird question but there is plenty along these lines on this worksheet
The wheel of a wheelbarrow has a 10-in diameter with a 2.00-in wide axle. If you apply 78 lb of force to move a load of 243 lb, what is the efficiency of the wheel-and-axle system? Answer in percent, and round your answer to 2 decimal places.
such as this
as well
but lets focus on the first question for now
I don’t know how you’re supposed to get that answer either
I thought it would just be this
yes me too
but i am very lost now
well
thank you for trying
ill see if anyone else has an idea
thank u
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Why for negative #s dividing by √ of 2X the leading term odd exponent (of the numerator) result in a negative #? See the attached; for both screenshots a positive # was 1st submitted. I don't understand why the formulas in hints make the result in either screenshot make the result negative.
Thank you kindly for your help
√ of 2X the leading term odd exponent (of the numerator) result in a negative #?
bad place to use the letter X as a substitute for "times", typing abbreviations notwithstanding.
@teal magnet are you asking why, for these limits at negative infinity, $\sqrt{x^2} = -x$ rather than $+x$ as one might have expected?
oh actually no that's not quite right.
Ann
I'm asking why a=odd integer; x^a/sqrt(x^(2a)) isn'T always positive.
right...
so you know how every real number has two square roots, one positive and one negative, and the radical symbol always refers specifically to the positive root, right?
wym "barely ever used that"
do you or do you not know that that's the meaning of the radical symbol and also the meaning one puts into the phrase "the square root of ___"?
I know that technically a square root can be negative, but I've barely ever touch that subject.
you've... successfully managed to avoid confirming that you do in fact know what i'm talking about.
i don't appreciate that.
let'S say I don'T know it, wouldn't that be better?
it would not be all that much better.
i would still need you to acknowledge it as said by me.
$\sqrt{x}$ means the \textbf{positive} square root of $x$, i.e. the one of the two that's greater than zero.
agree or disagree?
Ann
agree
Ann
the number $x^2$ has two square roots: $x$ and $-x$.
if $x$ is positive, then the positive root among those two is $x$, so $\sqrt{x^2} = x$.
but if $x$ is negative, then the positive root among those two is $-x$ (since $x$ itself is negative), so $\sqrt{x^2} = -x$.
Ann
agree or disagree?
if you mean the real #, the original is -|x| I understand
... ??
or sqrt((real #)^2)=x
i don't know what you mean by "the original".
i would appreciate if you did not strip my variables of their names.
otherwise you will force me to resort to convoluted and ambiguous variable-free phrasings.
which i don't want to do.
i mean... sure
it'll take two examples to illustrate my point ig
$\sqrt{7^2} = 7$, but $\sqrt{(-7)^2}$ is also $7$ and not $-7$.
Ann
I was to make the example....
ok then do it
(-2)^2=a a is 2, if I want the original #, I need to refer to -a
(-2)^2=a
a is 2
these two contradict each other...
sorry
you sound like you are first declaring a to be 4 and then in the same breath saying it is 2
which i don't think is what you wanted to say.
sqrt((-2)^2)=a a is 2
... ok
my example is over
please either @ or use the reply feature if you decide to try to help more.
@teal magnet so... did your original question get answered to your satisfaction? Y/N
N. if you could point to where in the hint formula the result becomes negative it would be nice.
$\sqrt{x^2} = |x|$, so for negative $x$ you have $\sqrt{x^2} = -x$.
Ann
in the first image, at the end of step 1/3, it says: ``In the denominator, let's divide by $-\sqrt{x^{10}}$, since for negative values, $x^5=-\sqrt{x^{10}}$.''
Ann
in the second image in the exact same location it says the exact same thing but with x^2 instead of x^10.
@teal magnet
where's the 1st part of any formula of that image spot making the formula output a negative?
I gotta do something 5-10 mins
@teal magnet Has your question been resolved?
I guess I'll have to memorize this. 😩 It doesn'T make sense to me why 2 negatives dividing one another don't become positive.
That sqrt(x^10) doesn't output the same as x^5, which AFAIK if it did both x^5 or negatives would cancel each negatives out.
I hate memorizing when there'S probably logic behind it that I just don'T get.
Are you asking why √[x^10] = -x⁵, for negative x?
Because x¹⁰ is positive, but x⁵ is negative, so you'd need a negative sign to make them equal
you are confusing "is negative" for "has a negative sign in front of it".
In my head sqrt(x^10) is the same as x^5. To me x^5/x^5 should always get y>=0
Well, try it.
What's (-1)¹⁰?
What's the square root of that?
Is that equal to (-1)⁵?
In my head sqrt(x^10) is the same as x^5.
this is what i spent a good amount of time trying to explain you is NOT the case.
but i see now it was all for naught.
I think they will output something different.
then why does the denominator introduce a negative?
sqrt(x^10) = |x^5|, and for x<0 this is -x^5 !!!
So the negative sign of "-x^5" makes it positive?
yes
That's a nifty trick!
I don't understand how it workd yes, but it sounds ingenious.
yet*
@teal magnet Has your question been resolved?
