#help-0
1 messages · Page 592 of 1
i would say take logs of both sides but wtf is log10(500000) without a calculator looooool
it's easier to divide both sides by 2000 first
2^(x/30) = 500000/2000 = x/30 * log(2) = log(500/2)
won't i still end up with log(5)
log 2 and log 5 are 0.30 and 0.70, they r standard values u can learn
but it doesn't say to use log5 as 0.7
oh
@wraith locust is correct answer -5??
I need help
How can I help??
@worldly oxide yes -5
Can someone help me visualize this?
Don't solve it for me though, I wanna know what's happening
@wraith locust want soln?
hold on
@dry echo does this help lol
OHHH
man, this is great
thank you so much!
I think you have to use law of sines or cosines iirc
this is about the extent of my abilities with blender lmao
@full wasp you know any reagent which can reduce Fe+2??
idk maybe like Ag(s)
@full wasp does Li work as it is strongest Reducing agent??
or cos54 = x/28, X=28*cos54
those are way simpler yeah lol
oops
good enough for me lol
yeah it would
@tiny cedar It doesn't work like that.
$$\cos(x) = \frac56$$
Chai T. Rex
uh fuck
If you only want one solution, that should be enough to start you off.
i mean
im supposed to do it w/o calculator
so is there rlly no way i can do this
this is the problem, its in spanish but i think the words dont rlly matter
i found cos x
wich is -5/6
Sorry, I have to go.
But here's something useful:
,w simplify cos(2arccos(a))
Oh, wait.
,calc cos(2acos(5/6))
Result:
0.38888888888889
oh
,calc 2(5/6)^2 - 1
Result:
0.38888888888889
But now I have to go 🙂
@languid ore 400??
@worldly oxide How would you find that answer?
where does the 45 come from
we dont use cos in my class could you explain how i could solve it without cos @worldly oxide
how?
please
okay
help!
nono its an ungraded content check
U calc volume for both hemisphere and the cone, and subtract cone from hemisphere
Cone’s volume is given as 1/3 pi r^2 h
the height of the cone is equal to the radius of the hemisphere
so the height equals the radius?
ohhhh
i got ot
it
tysm!!!
ok i got 28.3 as my final answer
Why is 9-(-13) = +22 shouldn't it be negative because the 13 is greater?
@south stream thats not 13 it is -13
ye a positive number is of course greater than a negative number if u think it like that
Why dont you write it like 49-63
When you subtract a negative term it is basically you're adding both digit
is this free?
??
Yep
Want area??
Which??
the one in the ss
there are 4 of them
Which angle mention the quadrant
is this a test?
No its hw
men and projects are directly proportional, men and hours are directly proportional, hours and projects are inversely proportional
lol
(m*h)/p=constant
I dnt get it lol srry
which grade are you in
do you know abt direct/inverse proportionality?
ok, first lets imagine we keep the number of hours constant
so for example lets say we fix the time at one hour
more men = more projects completed
less men = less projects completed
#men and #projects are directly proportional
does that make sense
Yes it does
now let's imagine we keep the number of men constant
for example we fix it at 2 men
if they have more hours, they can complete more projects
if they have fewer hours, they can complete fewer projects
so #hours and #projects are directly proportional
do you follow
Yes
ok now imagine keeping the number of projects constant
more men will finish the projects in fewer hours
if we have less men working then they will take more hours to finish th eprojects
so #men and #projects are inversely proportional
Yes
so now we have mh/p=constant
Ohh
I think I got it
Thanks
This should make solving other qs easier
np
I haven't solved it yet
after solving it
Sure ill send it
l
I got 32
What bout u?
k
K lol
32 is correct
yes ik
Can someone explain b. I having trouble seeing how you get to that number
Ok, quick simple question. Is >18 greater than or less than? Debate in another server
greater than
none
If it is greater than, then is 0>18 true? No...
that makes no sense at all.
Hmmm
Well it is just a symbol referring whether something is greater or less than
In that case, I am wondering why people think it is greater
Yes
18 does not make sense but i guess people might assume it as numbers greater than 18?
Can someone please help me
I came across this question and idk what to do
A Norman window has the shape of a semicircle atop a rectangle so that the diameter of the semicircle is equal to the width of the rectangle. What is the area of the largest possible Norman window with a perimeter of 47 feet?
Be sure to realize that the perimeter is just the outside of the window.
please lmn asap
looks like an optimization problem
first step draw a diagram if you haven't already
so let's say l is the length of the rectangle and w is the width of the rectangle
find an expression for the perimeter in terms of l and w
then find an expression for the area in terms of l and w
so using the perimeter equation, solve for l in terms of w, or w in terms of l, whichever one is neater
then substitute that into the area equation
now that you have the area functon in 1 variable, find the critical points of the area function
you still need help?
The way my first grade teacher taught us was to imagine the signs as alligators trying to eat the bigger number, so since the 'alligator' is facing away from the 18, 18 is less then the other number so [x>18] x is greater than 18.
kinda weird lmao
y" means double differentiation of y
is there a channel on this server to help with a math course ill be taking in a months time , it kicked my ass once before and i know ill need help with it
so at y' do I use dy/dx?
That is d^2(y)/(dx)^2
oh wow
Yes
then after dy/dx?
the first derive
what do I do next?
derive the next equation and discard the dy/dx at the left?
Differentiate dy/dx again
is the dy/dx on the left be affected?
I'll explain from start
First take everything except y to rhs
Find dy/dx
Now replace dy/dx with y'
Now find dy'/dx
@bold token
so it would be 8yy'?
oh didnt really need that, but thx
Can anyone help I’m doing past papers but I don’t know how to do this
hm
What is the derivative of x^2?
2x
And the derivative of 4?
y' would be 2x+8yy'=0?
that's what im thinking
but my teacher didnt explain that further xD
No no, this is not what y' is equal to
However, we can solve for y'
[ 2x+8yy'=0\Rightarrow 8yy'=-2x] Finish the rest
We have to find y" so there should be no y term
dackid (jump king +)
This is false
um
F I was wrong it seems
Im pretty sure some y would be left or smth
We are just doing algebra here by solving for y'
You forgot the negative, but yes
so it would be y''?
$x^2 + 4y^2 = 4$ is an equation of an ellipse
NickPro
No, that is y'. In order to get y'' we need to evaluate again
graphing is not needed atm
So the value of y clearly matters
yeah that's why y'=-2x/8y
then I derive -2x/8y to get y''?
So we have $y'=-\frac{x}{4y}$
dackid (jump king +)
wait somethinglike that
Now you need to differentiate again
Yes, then you differentiate this fraction
As we see, the chain rule will come in to effect again
Take the derivative of -x/4y
Ans should be in terms of x from what I have learned
yeah whats the derivative of 4y?
It's generally not a good idea to change the system of notations in the middle of your solution
Still false
4(dy/dx)?
You have a quotient of two functions -x and 4y
yes i know qouteinet rule
So you need the quotient rule here to take the derivative
jsut the 4y im worried
It cannot be in terms of x since you can have two different values for y for which the equation works
How did you understand the importance of variables for data analysis?
can someone help? im stuck on this question
Well y is a function of x, so you use the chain rule. And you are correct since the derivative of 4y is 4y'
So you would have to add plus-minus in the front
What's wrong with this?
Im not following
y is not a function
let me clear
Please ignore them Yogurt
Yes
now what would be the derivative of 4y?
They are the same thing
That's the same thing
oh xD
Just in different notation
This will not be an equation this time
so I just disregard y' on the left?
You'll have $y''=\dots$
dackid (jump king +)
The derivative of y' is y''
oh so y''=blahblah with y'
Why can't we take y as a function here ?
right?
That is the definition of the 2nd derivative
You will get two outputs for y
But if you recall the vertical line test, that means y is not a function
Ohh....
is this correct?
Ok thanks got it 👍
Its yogurt, take the derivative of -x/4y
aight
Didn't think of verifying whether it's a function or not
You are asking questions you'll know the answer to if you just take the derivative
This is why implicit differentiation plays a big role: you can still evaluate derivatives of curves that are not necessarily functions
I see
They can also still be functions, but with no clear analytic expression
Also true
i feel
Like inverse to a degree 5 polynomial
that my ans is wrong
So we differentiate y^2=4ax the same way right implicitly?
is (-4y+4xy')/16y^2 wrong?
Okay, recall the quotient rule [ \left(\frac{f}{g}\right)'=\frac{f'g-g'f}{g^2}]
dackid (jump king +)
In our case f(x)=-x and g(x)=4y
yeah I got this
dy/dx?
You calculated the derivative of y like 3 minutes ago
y' is
Why not just plug that in
-x/4y
Yes
You replace y' with -x/4y
Yes
aight on it
Ok so you replace y' in the end
Yes
Can this be done for functions too?
Indeed
Sure, but if we can write y=f(x), then the question becomes pretty straightforward
Nice this makes differentiation a bit easier
Nothing special here
This can be done for any curve given that it's differentiable
[-4x-4x^2/4y])/16y^2?
That's one of the ways we prove that the derivative of ln(x) is 1/x
Simplify, but yes
welp thx everyone
I see
You bet
Same way we can find derivative of a^x
\begin{align}
y=\ln(x) \Rightarrow x=e^y
\end{align}
\begin{align*}
\dv{x}(e^y)&=\dv{x}(x)\
y'e^y&=1\
y'&=\frac{1}{e^y}\
y'&=\frac{1}{x};; (\text{Recall equation 1})
\end{align*}
There ya go
dackid (jump king +)
Nah, that ones a bit different
Also, there is your proof for the derivative of ln(x)
But I found it
dackid (jump king +)
And so by the chain rule: $(a^x)'=\ln(a)a^x$
dackid (jump king +)
dackid (jump king +)
Give me a min I'll solve it
Alright. This one's a little tricky at first
Yes it is indeed
Keep in mind the variable is the base of the logarithm
Yes
Hey guys I need help with 12
Like I did the working and I got the answers however the answers only have two of the answers I have
Yh
So?
I found alpha and beta
and I have plus or minus 1/2 and 2/3 or 3/2
The answer gives me only 1/2,2/3
Help me I am stuck
@grand kelp
[ \log_x(a)=\frac{\ln(a)}{\ln(x)}]
dackid (jump king +)
That's honestly a very strange way to solve a quartic equation
Lemme look at this for a moment
I didn't think of that sheesh
@tribal geyser First, you lost the 18x^2 term in your equation
Nice job wolfram -_-
@grand kelp it’s using sum and products lol
so if u could explain that’ll be great
@grand kelp I didn’t lose it lol I wrote in at the top
You didn't
So I know the product is equal to -6, but what about the sum?
The sum is 52 / 24 afair
I don't know what the sum of the roots are for higher polynomials
yh
If u put it on a calculator it also gives u what I got lol
I got plus and minus 1/2 and 2/3 3/2
It just works the same, since you have $(x - x_0)(x - x_1)...(x - x_n)$
NickPro
But the equations gives 4 solutions
Well anyways [ \beta \cdot \frac{1}{\beta}\alpha\cdot -\alpha=-\alpha ^2]
How did u know which one?
dackid (jump king +)
no worries
And [ \frac{1}{\beta}+\beta +\alpha-\alpha=\frac{1}{\beta}+\beta]
dackid (jump king +)
dackid (jump king +)
Like if u try solve it u will get 4 solutions
Dackid give me more of those kinds of questions if possible
I’m lost
Yes
Can anyone help?
@tribal geyser What's your problem once again?
You don't know what solution to choose in a pair?
Yes because I figured out alpha which has two solutions and beta which also has two
So which one am I suppose to use
It doesn't matter because if you change the sign of alpha or replace beta with its reciprocal the solutions would stay the same
Are u sure because why would the answer only state 2 then?
Well, there isn't a valid reason to say that either of these answers is wrong so I assume the authors just gave one of the options
@coral pagoda It's not sqrt(6) since you have to divide that 6 by 24
sry
can someone help with this question?
Ah. My bad
idk
Less of a problem question but more understanding. When I have a taylor series, am I evaluating f(x)^n by the value of a?
Lets say ln x centered at a = 1. When expanding it, am I evaluating ln(x) and its derivatives at the value of a?
So it would be ln(1), 1/(1), -1/(1^2), 2/(1)^3....
Alright thanks.
are there any particular instructions (integration by parts / integration by substitution) to solve this problem?
i don't know what techniques you know, but one boring way I see immediately would be to expand the fraction by sqrt(25+x^2) so that you get rid of the root in numerator.
Could you proceed from there? Then you'd have to use an algorithm for such integrals.
im pretty sure it can be either way but which ever way is the easiest is preferable
adding to that you can also substitute x = 5sin(theta)
oh yes that's probably the most elegant solution
wait why would you substitute x = 5sin(theta)
i suggest you to try it and see for yourself what happens
if you are still confused then ask again
it's something that you have to see once or twice to be able to think of it
hi I need help with how to solve this
I dont know how to start solve when there is sin and cos
did you use the hint?
I put the hint instead cosx and what then? how do I continue
have you learned about this limit ? sin(x)/x
expand by (1+cosx)
substitute x/2 = t in the given problem and then relate (sint/t)^2 with that limit
This particular integral is actually pretty easy since this is a semi-circle centered at the origin with a radius 5
What you need is the top-right quarter of the circle
yeah then integrate the area of the top right quarter
It would be 25pi/4 I believe
what is sin(pi/4)
$\sin\frac{\pi}{4} = \frac{\sqrt{2}}{2} = \frac{1}{\sqrt{2}}$
NickPro
how from this you get to sint/t
I just get to 2sin(t)^2/x^2
Notice that $\frac{2\sin^2{\frac{x}{2}}}{x^2} = 2(\frac{\sin{\frac{x}{2}}}{x})^2$
NickPro
Now you can replace x/2 with t and get $2(\frac{\sin t}{2t})^2$
NickPro
@hollow owl
no problem
how about on the calculator
not everything needs to be done on a calculator
I’m trying to make the act faster im on time crunch
This doesn't have to be done on calculator
but if I did it on the calculator it would be faster?
no
1 + 36 = 37
2 + 18 = 20
3 + 12 = 15
4 + 9 = 13
6 + 6 = 12
All the options
@hardy geyser I don't know how you can find the divisors of a number on a calculator
so guess check would be the fastest way
I mean, 36 isn't a very large number
You can even check all the possible options, of which there's not too many
what if they give me a larger number
There are some techniques that you can use like estimating the numbers you can get, checking the remainders, etc.
Not sure the remainders would work but who knows
For example we have just found that all the options are 12 or larger
nvm I found a YouTube video I got it ty
Okay
Is that a pyramid?
are u kidding?
so it's flat?
I'm not, it maybe a triangle or a pyramid
Okay
48??
how did u guys solve it
because the triangles are the same
This can't be true
Because you're getting that the sum of angles is 144 degrees, not 180
tho it's definitely solvable
@woeful pulsar can u solve and explain if u can
there are lots of isosceles triangles
try marking down all the equal angles
see what relations you can make too
u sure?
Yes
what u mean with circumcenter
64?
@leaden hill You can draw a circle around the triangle
Have you studied things like that?
no kinda
new in thesethings
and what u say about that
ise means if
ABC is a triangle
it want how much is the X
Ever heard of Menelaus's theorem?
yeah
You can apply it for ABE and the line CD
thalesle yapıyosun onu
cevap 6 değil mi
ef/fb oranı de/bc oranı demek zaten
de/bc = ae/ac
thales işte
@leaden hill anladın mı
How would I approach this problem in a time effective manner?
what is this question asking for?
is it some sort of taylor series?
Whoops, sorry
firstly you can ignore the x^10 and just differentiate ln(1+8x)
this should give you 8/(1+8x), which you should be able to write the taylor series for easily, which you can integrate
i don't quite understand how im going wrong for this question
if sin(a)=-4/5 pi<a<3pi/2 and cos(b) =-5/13, pi/2<b<pi, evaluate tan(a+b)
This works beautifully
Thank you so much!
How would I solve this on a graph?
idk sorry
how does the determinant of (m-lambda*I) make the eqn 0?
the idea is that v is not zero, and neither is M - lambda*I
the only way you can get zero out of that matrix-vector product is if the columns of M - lambda*I are linearly dependent
if im given f'x and f(1) how would i find fx
integrate
thanks
you integrate and find the integration constant using f(1)
so like just substitute c for f(1)
no
you have f'(x), let's call its antiderivative F(x)
this F(x) is equal to f(x) + c
you know f(1)
so F(1) = f(1)
for example, say f'(x) = 1
and f(1) = 10
the integral of f'(x) is x
and 1 is definitely not equal to 10
however, there's also the integration constant in there, so that F(x) = x + c
then we say F(1) = f(1)
so 1 + c = 10
or c = 9
thanks
you know the product of all 4 roots?
I managed to get to when i got it to +- 2
what do you mean by products of all 4 roots?
nice you are ahead of where I'm suggesting
hold on while I think what to say
you mean a + b +c +d = -b/a
though you can try factoring it into two quadratics
So do I make ab = 2 and cd = -2
and then swap around with ab =2 and cd = 2
as well as ab and cd = -2
actually there are just two cases
$6x^4-11x^3-26x^2+22x+24=6(x^2+Ax+2)(x^2+Bx+2)$
OR
$6x^4-11x^3-26x^2+22x+24=6(x^2+Ax-2)(x^2+Bx-2)$
My friend and I were wondering why it can't be negative 2
Element118
just need to find A and B
erm
you have to try both cases
$6x^4-11x^3-26x^2+22x+24=6(x^2+Ax+2)(x^2+Bx+2)$
OR
$6x^4-11x^3-26x^2+22x+24=6(x^2+Ax-2)(x^2+Bx-2)$
Element118
I don't think I have LaTeX
if you start by evaluating the condition for the sum of 3 roots taken at a time you will get k=-2
what are the conditions
-22/6 = abc+bcd+cda+dab if a,b,c,d are roots
yeah
assume ab = cd = k
I mean is it possible if you can prove it with when you sub ab in into abcd
where ab becoem +- 2
but +2 for some reasons was rejected
we cannot make a conclusion from just abcd
Hey I'm really confused with this question could someone help?
This is part of my working out l and it shows where I got stuck
I'm pretty sure this question makes a 4x3 by 4x1 order
Which is not defined
Ahh I'm so confused
a looks about right
but for AX=B, X is your variables
i.e. x y z
@alpine sable
A should be n x m where n = number of equations and m = number of variables, X is then m x 1, forcing B to be n x 1
PrettyPrincessKitty FS
which is ax + by + cz
Ahh alright
if you write out A to be [a b c // d e f // g h i] and X to be [x // y // z] and multiply it out
you'll see it
C wants you to find x, y, z
math is tough
@lament wyvern
why is A a 3x4
each row corresponds to 1 equation
you have 3 rows, yet 4 equations
I count 4 rows
so your matrix should have 4 rows
And I don't see how column can rep the corresponding equations
Ok so I was right like this:
yes
Then why isn't it working
if you write out A to be [a b c // d e f // g h i] and X to be [x // y // z] and multiply it out
you'll see it
Like as in draw it Because I can't understand it sorry
I'm sorry, I just can't visualise that.
AX=B
you have your A
you have your X
idk how else to explain it
you can, though
so I've drawn it
if you do the multiplication, you'll get ax + by + cz
So where does the total taking ls go?
where can it go?
why are you inverting it
Because it wants a^-1
I mean you don't need to throw it in a calculator
I'm though because it goes against what I have been learning, usually the x,y,z is just for reference and then you times the other two and invert the equation matrix
Here I'll show you
yeah I mean maybe you've been taught different
but usually you put it in an augmented form, row reduce the matrix, read off the solution
ah okay, so what you're doing there is you have AX = B
A^-1AX = A^-1B
IX = A^-1B
X = A^-1B
And there's the question
Yes but I'm pretty sure that's what it's asking
Not only thAt but it's a 3x3
Np
yeah you know what A is
Yes
idk how to use a CAS to find the inverse
okay, so you should be able to put that A matrix in
just the A matrix, nothing else

sorry, I got confused by what you were asking
yeah sadly I have no idea how to solve that, it seems like a calculator problem
nonsquare matrices can have inverses
Therefore Its undefined
I don't think so
Because all the calculators online are asking for perfect square matrices
And wont let me modify it to 4x3
Oh well
or rather, it has 2 inverses (if it's not singular)
oh wait, no
yeah because the commuting makes no sense
What
A-1A = I = AA-1
doesn't make sense for nonsquare
so then you have (A-1L)A = I = A(A-1R)
for the left and right inverses
I've gotta be honest, the question is confusing me
because A cannot be square
and yet it wants an inverse
Yes
Thats what I was getting at
Maybe it has something to do with the question
Or maybe ijt doesnt
Maybe it's an absolute giga brain equation
Anyway thanks again @lament wyvern
np, sorry Icouldn't help more
3 plus 1?
btw was wondering if anyone could help me with this. unsure what where this 3/5 come from
uh, looks like they've multiplied the entire thing in the step before by 3/3
so you get $\frac{3sin(3x)}{3.5x.cos(3x)}$
PrettyPrincessKitty FS
then you can pull out the sin(x)/x => 1 bit
\cdot ,\sin and \cos
ty
you get 2 simultaneous equations
Oh
write the first equation in terms of powers of 3 and compare powers
First equation i got x=y
Correct?
2x+1=3y i think
3x3^2x=3^2x+1
Umm... I'm new to this server, saw this question and I hope this helps you... (Pardon the handwriting plz)
laws of exponents
its 3x3^2x so powers will be added
Thanks!
But i found the ans
Appreciate ur help
Can chi-squared test use the value 0 (zero) as the frequency?
is it an ideal gas?
If the gas is assumed ideal then the calculation is simple, if it's not assumed ideal you need the van der waals
Ok so you can assume it's ideal?
$PV=nRT\implies V=\frac{P}{nRT}$
moshill1
Yeah that's the ideal gas equation
ok so .09atm is 9.11925kPa
so then plug in all the numbers
$V=\left(\frac{9.11925}{(7.7)(8.314)(56)}\right)^{-1}$ cba to tex in the units
moshill1
,w calculate (7.78.31456)/(9.11925)
Yeah but you got on the order of 2000L, when it should be around 1/5 of that
Im saying im shit at sig figs LOL
try scientific notation?
$390=3.9\times 10^2$
moshill1
Yeah well math says the answer is 390 so I'd talk to your teacher / prof about it
significant figures play a role in approximation i don't know how exactly but you can read about it
try 400
cause i cant recall if .09 is 1 or 2
Ok so it was to 1 sig
Yeah you had 2, 1 and 2, so division takes the fewest
Yeah sig figs are just a thing you do
they help in error propagation; I think
I mean I'd want the most accuracy in error prop not a sig fig value
then round off the average and deviation
the intention is to give the most accurate approximation keeping the error propagation in mind
iirc
My 2 cents is just round appropriately / that's what I plan on teaching
yes
keep to 4 sig figs
That's my guess, yes
Well yeah, the answer is ~.301 so the answer bank is probably wrong 
how do i approach the first one?
do i try get it into reduced row e form with the variables
existence of free variables means the solution isn't unique
yeah it helps to get M_2 into RREF
so you can see what the leading 1s and therefore what the leading variables are
right i'll try do that
That number is 0.4 and the 4 is in the tenths place
Which means whatever number is in the tenths place is divided by 10
you still there?
any progress?
i have been trying to rref it but i feel im doing smthing
wrong
is the first step to do r3/ 9-k?
did u do gauss-jordan elimination?
nope
do u know gauss-jordan elimination?
it's a method of reducing a matrix to its RREF
can you show what you did
so basically first i divide R3 by 9-k to get a one in the bottom left
and i work my way to get to the rref and have values with k and h in the augmented part
umm
if i try get the ref for m1
nvm
!superficialsicko
because otherwise there is no solution
by itself u mean 9-k right?
take lcm from the lower most term
come in Q3 or some other which is vacant
sorry?
what's the rref
im still doing it
just to make sure im on the right track, i should get x y and z in terms of h and k right @tough hatch
after rref
x y and z are the variables you are going to classify as either leading or free
then if one of them is free
no unique solution
?






