#help-26
1 messages Β· Page 138 of 1
Yeah, I've heard it's needed for eigen-stuff
It is also fundamental to making projection matrices
And just projections in general as you are doing right now
wait, w1 = (1, 1, 0) and w2 = (0, 1, 1) though I thought?
v - c1 w1 - c2 w2 = (2 - c1, 4 - c1 - c2, 3 - c2)
I thought w1 = <3, 3, 0> and w2 = <-2, 2, 4>
No, those were the projections we calculated using the previous method
That method was wrong, my mistake
Sorry
This method should be faster and work correctly
By w1 and w2, I mean the two vectors that span S in the original problem
Ohh, okay
Now I'm getting c1=-11 and c2=8
How'd you get that
I used dot product to get the system
2*c1 + c2 = 6
c1 + 2*c2 = 7
that's right, but your solution for c1 and c2 isn't right
(for example 2*-11 + 8 = -14, not 6)
c2 = 8/3
c1 = 5/3 ?
Let me check with substitution
Yeah, I'm getting those solutions
Are those the solutions you got?
You mixed up c1 and c2, I think
So c1 = 8/3?
No I mean
c1 = 5/3 and c2 = 8/3
But it looks like you accidentally did c1 = 8/3 and c2 = 5/3 in your calculation for the final answer
yea
So I have a visualization of what I think the porjection is, but I don't really know waht it means or does
I notice that the projection bector lies on the span of <1,1,0> and <0,1,1> but it isn't orthogonal to <2,4,3>
Projection is the opposite of what you are thinking
It is the closest point to (2,4,3)
If (2,4,3) was in the span
That makes sense now that I think about
The projection would have just been (2,4,3)
So projection of a vector is the closest that a scalar multiple of the vector can be to another vector
and the projection of a subspace is the closest that a vector in the span of the of the subspace can be to another vector
Projection of a vector onto the subspace
My bad
You can actually see this
Because the difference between vector and the it's projection is orthogonal to the span
It was already used here
It would be normal to the plane
Like a normal line in calculus?
No like a normal line to a plane
If you are talking multivariable calculus where they taught you the definition of a plane yes
I haven't taken calc iii yet
Just google
I was kinda thinking this
Ignore the red curve here, the blue line is normal to the green one
(normal just means perpendicular)
We're only working with linear stuff rn
Okay
I just used the red curve to make the green and blue ones
I was going to ask about the least squares regression problem, but it's getting a little late
Thanks @dusk adder & @urban grove
.close
np
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you're welcome!
Like this?
The blue line does look normal to that plane yes
Cool, thanks again
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ok ques time
for me
im kinda confused here
I wanted to practice some algebra
and I found this on one site
gaussian elimination?
what is 2+2
ig 2R1-R2->R2?
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yw
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In a randomised controlled experiment are there no omitted variables
you supposed not to or can assume that the expectation of that is zero
There are omitted variables (I mean, randomization would not change the fact that I have a certain gene for example) but those should not influence the treatment (i.e., the distribution of people who have a certain gene should be randomized enough to not have effect on treatment effect)
So there are omitted variables but they don't possess an influence on the study
But then
Isn't the definition of an omitted variable one that DOES influence the study
And it has been wrongly excluded
So technically those variables are not "omitted variables"?
I mean. Yes. For example, suppose we have a new drug to reduce blood pressure. We let the participants consume it and let them go home and come back to check. What patients eat at home can influence their blood pressure, but does that count as an omitted variable? RCE ensures that those are evenly distributed (hopefully) and mitigate those biases.
Meal does influence blood pressure, but if we only care about the effect of the drug, RCE remove those effects
(hopefully)
So would you say that
"There are no omitted variables in a randomised controlled experiment" is True?
There should be no omitted variables bias in a randomised controlled experiment. The variables are still there (like meals) but the effects are even out from randomization.
@queen cloud Has your question been resolved?
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k is just the normal variable people use for growth rate
$P(t)=60\cdot (2)^{(3t)} \to P'(t) = 60 \cdot 3 ln(2) \cdot 2^{(3t)}$\
or\
$P'(t)=3ln(2) \cdot P(t)$ \
giving by definition a relative growth rate of $3ln(2)$ (the amount $P(t)$ increases at a rate of $3ln(2)$ of its amount)
Crystopher
so 3ln2 is correct?
if we assume that your function P(t) is correct, then it should be 3ln(2)
how did you arrive at your results?
i just used average rate of change in the given interval π
i have no idea what it wants
b) states basically that given two points $(1800,980)$ and $(1850,1260)$ find a function $P(t)=P_0e^{kt}$ with parameters $k$ and $P_0$ that goes through these points, then use it to find $P(1900)$.
Crystopher
would this work
that should work
a bit different to what I had in mind but still seems to check out.
@dense cosmos Has your question been resolved?
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.reopen
wait is the one solution 0?
I was confused for a second but I thinkk the only value that makes sense is 0
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Can someone explain to me why my solution sets are wrong?
Please don't repeatedly close and claim a new channel with the exact same question. This erases all previous progress made towards your problem and is confusing for helpers, making it more difficult to help you. Please be patient, even if your channel has not received much attention.
you just fliped the sign
i was told to flip the sign to get rid of the -1/5
so should i have not flipped the sign
pretend im new to math
i have been stuck on this problem for hours
- and 1) is the correct answer
Moo
correct answers
- is fifth, 2) is first i mean
(β2, 3) βͺ (4, β)
(ββ, β2) βͺ (4, β)
(β2, 4)
(β2, 3)
(ββ, β2) βͺ (3, 4)
these are my options for the answers
LOL
your answer doesnt fit into any of these
ok
can you circle on the problem where i did it wrong then?
so i can learn and know for next time
if you don't divide both sides by -1/5 but 1/5, the answer is clear
okay
f(x) = -1/5 (x+2) (x-3) (x-4)
original problem
I want to find f(x) > 0
so now its
(-1/5) (x+2) (x-3) (x-4) > 0
is that correct so far?
this one is wrong
the fliped function isn't anymore f(x)
let's assume that is f'(x)
wait i dont want to confuse myself even more if i dont have to..
so should i just have not fliped the sign
my teacher didnt teach me inverses yet
i was just told to divide both sides by -1/5 to get rid of it
and because of that i flipped the sign
can i do it without flipping the sign
(-1/5) (x+2) (x-3) (x-4) > 0
divide both sides by 1/5 correcct?
yes.
yeah,
do we have to do anything with the -1?
of course
ok
so i now have the equation
(-1) (x+2) (x-3)(x-4) > 0
now i do the line with the points correct?
yeah
?
what steps did u skip
im only at the number line rn
so now i have the number line
-2 , 3 , 4
do i do -1 too?
or ignore that
if x=-1, (-1) (x+2) (x-3)(x-4) = 20
um
thats different from the method i did in the picture
π
this is the part im confused on
and have been for the past 2 hours
bc no one explains it
this is what i have so far
yes
so are we just not doing the number line?
i made an error cuz i'm tired too
whats the calculation for?
im on the number line and i dont know what this calculation is for
let me explain this
if x is bigger than 4,
x+2 >0, x-3 >0, x-4 >0
that means f(x)is smaller than 0
right?
wait
can i ask you why my method didnt work?
and why you chose this method instead
my teacher told me once I graphed the numbers on the number line
(-2 , 3 , 4)
we have 4 intervals
and then we choose a number within those intervals to test
so i chose -3 for the first interval
0 for the second interval
3.5 for the third interval
5 for the fourth interval
then
for each interval
i input it into x
so for first interval
when x = -3
(-3 + 2) = -1
(-3 -3) = -6
(-3-4) = -7
so that section is negative
is it because i need to multiply eveyrthing by (-1)?
because i got - + - +
but since theres -1 do i just do the opposites?
that's it
ok
thats literally the part ive been stuck on for 2 hours
i didnt know why it was opposite
okay
let me try to explain
as the problem says fx = -1/5(x+2)(x-3)(x-4)
then if we introduce a new function g(x) which is equal to -1/5 * f(x)
g(x) = (x+2)(x-3)(x-4)
right?
yea
in this case, about a specific x if g(x) < 0,
what about f(x)?
f(x) = (-5) * g(x) > (-5) * 0 = 0
right?
where is the -5 from?
we just assumed that g(x) = (-1/5) f(x)
that means f(x) = (-5) * g(x)
okay g(x) = -1/5 * f(x)
if we divide both sides with (-1/5)
i think if we were in vc it would make more sense to explain
- fx = -1/5(x+2)(x-3)(x-4)
- g(x) which is equal to -1/5 * f(x)
why are we multiplying f(x) by -1/5
is it to get a coefficient of 1?
maybe. you can multiply by -1 instead of -1/5
the result is same.
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- A wolf runs along a straight road that goes directly from her lair (W ) to Grandmotherβs house
(G). Some of this road is on flat ground and some is downhill or uphill. The wolf runs downhill
at 20 km/h, on flat ground at 15 km/h, and uphill at 12 km/h. It takes the wolf 3 hours and
27 minutes to run from W to G. It takes the wolf 2 hours and 33 minutes to run from G to W .
Which of the following is closest to the distance between W and G?
(A) 33 km (B) 36 km (C) 39 km (D) 42 km (E) 45 km
!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
@ripe heron Has your question been resolved?
x=vt => t = x/v is a good start
huh
x is distance
v is speed
t is time
if you still don't understand I will send an ss that creates the equation
k thx
i still dont understand
so after everything is the answer 45
yes
I can try
What is the sum of the rightmost two digits of 106^2024?
chatgpt gave me 15 π
idk if its right or wrong tho
i'm sure about I have to find a pattern or sth like that but I have no idea how can I find one but gonna try
k thanks
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hey
Pick for example theta_1 = theta_2 = pi/2
mhm
what happens?
uhhh, im not sure? i don't understand what you are asking.
ah ok
Im asking you to simply try some values
like these
oh yeah, i know they dont equal i just want to see some sort of proof.
well that is a proof
proof by contradiction?
if u want a proof for more general case, have u been taught compound angles yet?
nope, its a perfectly valid proof by counter example
because my rational is they should be equal sine x(a) + x(b) = x(a+b)
why?
sin is not being multiplied by a or b here
it's not the distributive property because it's not multiplication
oh yea, its a ratio...
it's a function application, which is different and just happens to use the same notation
well. thanks yall! i just needed to know that because im confused about the cast law.
ive never heard of cast law
the thing you have to learn here is that linearity is a special property and not something that works for just about any function
i feel like the term linearity wont mean much to them at the moment
how could sin (180) =-0.801152635734, how can you have a triangle with negative length?
im calling it by name, to make it more obvious it's a special property
well first you should probably switch to degree mode instead of radians
yeah fair enough
radians
You can switch to degrees in settings (top right)
Out of curiosity, has your teacher shown you the unit circle or are you familiar with it
desmos sin(x) is a generalized notion, than that of the definition from a triangle
but my point being, how can some trig values be equal to negative if you can't have a negative distance? no im just studying on my own.
sine is defined a little differently outside of 0-90 since you can't use right triangles
yeah
so the definition is generalized
it makes sense once you encounter the unit circle
there are videos on youtube that will teach u the unit circle concept better than we can probably word here on discord
Courses on Khan Academy are always 100% free. Start practicingβand saving your progressβnow: https://www.khanacademy.org/math/algebra2/x2ec2f6f830c9fb89:trig/x2ec2f6f830c9fb89:unit-circle/v/unit-circle-definition-of-trig-functions-1
Extending SOH CAH TOA so that we can define trig functions for a broader class of angles
Practice this lesson y...
diagrams will probably help more than texts for this topic so i would consider just watching these videos
i tried to look but i couldn't find any, they all used ref angles and i don't get why ref angle has to be the one adjacent to the x axis and why using the unit circle to get the trig values could translate to triangles.
my first road block was sin (110), i thought that you could just get sin (90) then add sin (20) but i see thats wrong.
so i was confused why you would need a ref angle
infact distances aren't now negative, here the triangle is instead represented in a coordiante system, so the coordinates may be negative, but we still treat distances between points as non-negative
play around with this
notice how the triangle is still there
yeah I was confused about that, how can a negative coordinate translate to a triangle which can't have negative distance. i was looking for some sort of geometric proof too.
it's just a rather convenient generalization
if you tried to keep the coordinates positive, youd have ugly jumps
and again, the distances arent negative its the coordinates
we've changed represenation here
The negative sign should be thought more of as direction than anything else
so, what i am confused on, is why we would use a ref angle, and if there was any geometric proof to show that a triangle with a sin value would correspond to a coordinate that on the unit circle.
i can see that the unit circle is already a geometric proof of most trig functions, but i want to see if there was anyways to translate transformation in the unit circle into math steps, like how would you represent a turn of the radius to some angle theta on an equation.
well, thats all i guess. thanks for the clarifications.
im not sure what you mean by ref angles, but for the latter imagine you're on the 1st quadrant and have a unit circle. Place a right angle triangle such that the hypotenuse is the radius of the unit circle, so it must be a distance of 1. (refer to the desmos link)
yup
now (again refer to the desmos link) given some angle a, which is between the adjacent side, origin and hypotenuse
so like this
oh ya
again we know the hyp is 1, could you express the other sides in terms of sin and cos?
yes you could repersent the adjacent side as cos and the opposite as sin
cos (a) and sin(a)
yeah and why?
because both those functions equal to some number x over the hypotenuse which is 1
Sorry, i cant quite follow; let me ask you the defintions of cos and sin instead
What are we doing here?
oh its opp/hyp for sin and adj/hyp for cos, we are doing trig.
Question?
yup!
What is the Question?
okay cool, now since we're in a coordiante system
im clearly already helping them rn?
just scroll up idk
i just didn't understand how the sin values could be negative since that implys a negative ratio which means a triangle with negative distance. and how the unit circle is relevant to a triangle.
K but still
now, since we're in a coordiante system
notice how from the origin traversing a distane cos(a) to the right
we land on the coordiante (cos(a), 0)
Ok, but if you guys still need help ping @jaunty badge
so if we imagine a line segment from (0,0) to (cos(a),0) what would that represent?
a value of x
Sorry, whats x?
the distance from the origin to the x axis which is also equal to the cos(a) in this context.
yes the x- coodinate
like if you had a line segment from (0,0) to (cos(a),0) what would that look like?
yes
so what im trying to get at is that this line segment is just the adjacent side on our triangle
do you see that?
ya
and how the point (cos(a),0) would then be the right endpoint of that line or in other words the bottom right corner of the triangle
yes
so now imagine we're on the point (cos(a),0)
mhm
let's traverse upwards by sin(a)
yes
where would we land you reckon?
at the end point of the hypotenuse
yup!
so if our right triangle lives in the 1st quadrant, we're able to use the definitions from geometry (since our coordinates will be positive) and the points on this triangle can be expressed with cos(a) and sin(a), and so we havent really done anything different yet apart from representing points of the triangle as points in a coodiante system
yeah
now notice, once we move the right triangle say to the 2nd quadrant, our triangle will be flipped horizontally if it must obey the same conditions as we said earlier, i.e hyp is the radius of the cirlce etc
but now our x coordinate for example will be negative if we talk about the corners of the points we talked about eariler
we'd like to keep using say the point (cos(a), 0) to describe that corner we mentioned before
or even (cos(a), sin(a))
yes but, when we do that, a becomes the exterior angle though.
the natual thing to do here is if our angle a is greather than 180, then the cos(a) should be negative, to account for this change in the coordiate sytem
Yeah sure
and if that happens then the values of the trig functions would be respective the exterior angle not the interior one, and the exterior angle does not form a right angled triangle but an oblique triangle
Yeah so that's perfectly valid if you want to keep the coordinates positive, but what we want here is be able to represent the same points the same way we moved it, i.e the x-coordinate of our corner will be negative. Also notice that the point (cos(a),sin(a)) will act as a rotation about the origin
if we let cos be negative, once in the 2nd quadrant, we can start rotating things rather nicley aswell, as you would in real life
yeah but the interior angle is not equal to the exterior angle so how could you use the interior angle to represent the exterior angle.
So youll have that the interior angle + exterior angle = 180 (if we treat the x-axis as our floor in this case)
just solve for whatever youre keen on knowing
wait...
nvm, i am still confused, thanks for the help though - you cleared up most of the confusions i had
can i ask you a different algebra question?
im glad i could help, sure!
it one that i have been having trouble with
ok so...
can you solve this system of equation step by step, i have been having trouble with it. i think i do the steps correctly but the results never make sense
Hm let's try
I should start by asking what progress you made, so i could focus on something in particular
so, i can solve for x in the first equation, then i plug it into the third equation and solve for y
then i plug x again into the third equation
this yealds me some sort of quadratic equation with two variables instead
then i plug in y from the previous equation and plug it into the third equation
this only leaves z then i solve the quadratic and the results dont make sense
when i input the value of z in desmos, the graphs don't get a point where they all intersect
Alright, let's try something different
oks
so let me just label these, so we have the system
$$\begin{cases}
x+2y-z=2&\quad (1)\
3x-y+2z=7&\quad (2)\
1/x+y-z=0&\quad (3)
\end{cases}$$
ok
Aslan
notice that if we multiply equation (1) with 2, we get 2x + 4y -2z = 4, right?
yeah
so by adding (1) and (2) we get 5x + 3y = 11, right?
yup
alright lets remember this one and instead notice something else
ok ok
if we say subtract (1) from (3), what do we get?
we get, 1/x - y -x = 0
almost!
oh and i already made a typo lol, it should say 2y and not 3y
or no, nvm ignore that
hm. i really cant fact check you rn so im just comming along until it clicks :d
because i have been focused on that equation for the past week and every where i search its always just a quadratic system with only two variables and rn im just desperate for some sort of mental ease, don't worry, im following along.
alright!
π
so going back to this
ok
oh wait. wouldnt it be 0 though? because you substracted a negative by a negative so the negative becomes additon.
so when you subtract or add equation, formally what we really mean is that we are subtracting or adding each side separately, if that was unclear
so on the RHS, we are doing 0 - (+2)
oh so like x+y+z - ( x+Y+z) not each term substracted seperatly?
Let me show it more explicitly maybe
ah yeah i got it dont worry
you sure?
Well, just to make sure we're on the same page. Say we have the equations w = 4 and k = 2, could you add these two for me?
yeah! so that would be the RHS and LHS resp. !
I.e we have that w+k = 6
makes sense?
so is it the one with the brackets or the one without.
it would be the one with brackets, but this is only the LHS, we also have a RHS of the equation
so going back to this example
yeah?
could you subtract say w=4 from the eq. k=2?
w - k = 2
Thats correct, if i told you to subtract the eq. k=2 from the eq. w=4; but it seems youre on the same page atleast
alright, so do you now see why we're missing a -2 on the RHS here?
yeah, so for the other equation it would equal 1/x -x -y = -2 oh yeah my bad i forgor about the rhs
yeah
5x + 3y = 11
mhm
Let's solve for y here
yeah
What do we get?
we get y = (11-5x)/3
k
we should now have an equation in one variable
yeah
could you write it for me?
element
missing a RHS here!
element
: - )
neat!
after a bit of algebra we have the equivalent equation (3+6x)/x = 11 - 2x
would you agree?
alright cool, you might see where this is going, now multiply the nonzero x to both sides to get a quadratic equation.
Namley 3+6x = 11x - 2x^2
ya
I suppose you can solve this one on your own?
element
I can provide atleast one solution, x=1
Check this by plugging it in
Thereβs one more however
yeah i already knew the values of those varables, so this works. and yes there is the second value
but my one problem is
But uh, this isnβt right?
this worked but why didn't it worked when i didn't do elimination and dis substitution through out the entire system.
i mean why didnt it work when i did substitution through out
the entire system
In theory it should of worked
this time you used elemination and then substitution but when i used substitution through out the entire system it didn't work.
i don't know why that is, do you? or it was just a miscalculation on my part.
It could be just due to a mistake, but in principle it should work too
I havenβt seen the explicit work for me to judge though
because when you don't use elimination you get massive numbers like $54x^{2}-132x+46=0$
element
and when you solve it, it gets bigger
but anyways, thanks for your help, atleast now i know how to solve em.
i guess ill ask a teacher when i get back to school.
If youβre getting different solutions to that quadratic, then youβve made a mistake
yeah, its when i solve the quadratic i get a different answer.
but its not the quadratic that i miscalculate, its at the steps before. because when i check my quadratic equation answers in a calcualtor they make sense.
You did however also not provide the correct solutions to this, so it could very well be a mistake on your part
Like when solving the quadratic
wait what was my answer?
This
isn't that the solution?
As I said, one of the solutions is x = 1, but neither of them is that
i used the completing the square method this time and it made sense through out, lemme do that again
@final hollow Has your question been resolved?
@final hollow howβs the progress?
ah i see, i messed up because i divided by -2 instead of 2
i just got that...
wait lemme send you wnat i got
$x=\frac{5-1}{4},x=\frac{5+1}{4}$
element
well thats all. thanks π
Great! Ur welcome 
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xΒ²+3x
6xΒ²+24x
can i cancel out the xΒ² numerator on top with the 6xΒ² on the bottom to make it 5xΒ²? and can i also just divide 24 and 3 individually?
if you want to cancel things on fractions, it has to apply to every term. you cant do anything to individual terms
so how would i simplify this fraction?
factorise so that the numerator and denominator has common factors and then cancel
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Need help with this stats question π
what is percentile?
if you understand the definition, this should be more obvious to you
I will say that there are a lot of ways to answer this question, however. Many of them result in a slightly different answer.
but that depends on what is being taught in your class
Iβve put the answer 6.8 it didnβt work and I canβt understand any other way of finding the answer
i believe 6.8 would be the 30th percentile?
I mean, you are not entirely wrong. 6.8 is lower bound for the 40th percentile
but I think you can do better
Hint:|| Think about the position. What does that decimal point tell you?||
Are you telling me Iβm supposed to arrange them by the lowest to highest decimal point?
no
when you find the percentile, you need to find the position for that, correct?
what is that position?
Well I mean it would be the 4th box no? πββοΈ
nobody
are you sure?
Anyway... if it is like .4, you know that it should be far off from 4 but not that far that it becomes 5.
you know that your 4th position is 6.8 and 5th position is 16.1
so your percentile should lie inbetween that
not really
one of the way to approximate that is to think that if the length between 6.8 to 16.1 is one unit, what is the length of 0.4 of that unit?
like... if it is 4.5, you know that it should be in the middle between 6.8 and 16.1
Honestly dude Iβm actually fried I donβt get this last part at all
Alr Alr I UNDERSTAND THAT
so you approximate that
Soo I would think 9.3 or 10.3
well... you know that it is 0.4 position more than 4th position. so if I know that one position around there is 16.1 - 6.8, then 0.4 of that is...
(like, you need 16.1 - 6.8 much to turn 6.8 [4th position] into 16.1 [5th position])
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A ball weighs 0.3125 pounds. How many foot-pounds does it take to throw a ball 90mph.
foot-pounds?
what's that in SI
Newton meters
ah
so work
Yeah
ok, maybe I can help
uh
1/2(mv_2^2)-1/2(mv_1^2)
what units is the answer in
Foot pounds
,w 0.3125 pounds to kg
,w 0.5(0.14175)(40.23)^2
,w 114.707 Newton meters to foot pounds
must have made a calculation mistake
How
maybe work in SI and then covert to imperial ?
90^2x0.3125x0.5
Because thatβs the units we using
not feet per second
no, I mean convert the speed to feet per second
I'm not familiar with calculations in imperial, so I can only guess
but because the standard unit of time in imperial is second
stick to metric, calculations are much easier
Yeah I donβt need to know thereβs 37393746.27384 feet in a mile
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question
why is f(x)=2x^3-3 an even number?
That's a function and it is also odd for all integer x
oh f I'm stupid πππ...
i just realised
sorry for wasting your time idk what got into me
No worries
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It is more of a general question in techniques of evaluating power series
context is highschool math and power series isnt a stand alone topic
Overall I find it quite hard to evaluate power series and idrk where to proceed with them
i haven't been taught any techniques or general guidance in how to evaluate these series so I was wondering if anyone here have readings or general suggestions in solving these
@glass maple Has your question been resolved?
There is not really a standard way of evaluating power series, except itβs like a known series
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Hi! I'm making a tower defense game and I want to calculate where the tower should shoot the bullet to hit the monster and the equation would look like this where everything is constant except for x,y :
x = monster.rect.centerx + (monster.direction[0]*sqrt((x^2) + (y^2))) - self.rect.centerx
y = monster.rect.centery + (monster.direction[1]*sqrt((x^2) + (y^2))) - self.rect.centery
I want to somehow solve these equations to:
x = something
y = some other thing
well are the monsters only moving in the same direction always?
otherwise your turret will definitely miss if they turn a corner
yeah rn I don't care about that this will be good enough
please someone help me <@&286206848099549185>
@vast vector Has your question been resolved?
@vast vector Has your question been resolved?
@vast vector Has your question been resolved?
Dist = sqrt((monster_pos_x + monster_vel_x * t - turret_pos_x) ^ 2 + (monster_pos_y + monster_vel_y * t - turret_pos_y) ^ 2) = t * proj_vel
solve for t
then
monster_pos_x' = monster_pos_x + monster_vel_x * t
aim turret at (monster_pos_x', monster_pos_y')
@vast vector
hmm
solving for t should just be a quadratic
t = (-monster_pos_xmonster_vel_x - monster_pos_ymonster_vel_y + monster_vel_xturret_pos_x + monster_vel_yturret_pos_y - sqrt(-monster_pos_x**2monster_vel_y*2 + monster_pos_x**2proj_vel*2 + 2monster_pos_xmonster_pos_ymonster_vel_xmonster_vel_y - 2monster_pos_xmonster_vel_xmonster_vel_yturret_pos_y + 2monster_pos_xmonster_vel_y**2turret_pos_x - 2monster_pos_xproj_vel*2turret_pos_x - monster_pos_y*2monster_vel_x*2 + monster_pos_y**2proj_vel*2 + 2monster_pos_ymonster_vel_x**2turret_pos_y - 2monster_pos_ymonster_vel_xmonster_vel_yturret_pos_x - 2monster_pos_yproj_vel*2turret_pos_y - monster_vel_x*2turret_pos_y*2 + 2monster_vel_xmonster_vel_yturret_pos_xturret_pos_y - monster_vel_y**2turret_pos_x*2 + proj_vel**2turret_pos_x*2 + proj_vel**2turret_pos_y*2))/(monster_vel_x**2 + monster_vel_y**2 - proj_vel**2)
,
t = (-monster_pos_xmonster_vel_x - monster_pos_ymonster_vel_y + monster_vel_xturret_pos_x + monster_vel_yturret_pos_y + sqrt(-monster_pos_x**2monster_vel_y*2 + monster_pos_x**2proj_vel*2 + 2monster_pos_xmonster_pos_ymonster_vel_xmonster_vel_y - 2monster_pos_xmonster_vel_xmonster_vel_yturret_pos_y + 2monster_pos_xmonster_vel_y**2turret_pos_x - 2monster_pos_xproj_vel*2turret_pos_x - monster_pos_y*2monster_vel_x*2 + monster_pos_y**2proj_vel*2 + 2monster_pos_ymonster_vel_x**2turret_pos_y - 2monster_pos_ymonster_vel_xmonster_vel_yturret_pos_x - 2monster_pos_yproj_vel*2turret_pos_y - monster_vel_x*2turret_pos_y*2 + 2monster_vel_xmonster_vel_yturret_pos_xturret_pos_y - monster_vel_y**2turret_pos_x*2 + proj_vel**2turret_pos_x*2 + proj_vel**2turret_pos_y*2))/(monster_vel_x**2 + monster_vel_y**2 - proj_vel**2)
@old cloak how do I know which one to use for t?
should just be the positive one
no solution if both are negative
t = max(t1, t2);
if (t < 0) {
return Null;
}
well no if both are positive then you should pick the smaller one
not sure if possible
proj vel is the projectile's x or y?
it is both combined
in what way?
ooh
velocity as a vector
but also you should go from proj_vel to proj_vel_x and y and not the other way around
it's a constant that you should decide
okay I'll get back when I implemented this in my code
and what is the monster_pos_y'?
' is used for changed / updated value, in this case it means future position
oh I subsitute everything into a solved version for y of this?
y = monster.rect.centery + (monster.direction[1]sqrt((x^2) + (y^2))) - self.rect.centery
what I wrote should do everything that you want, not sure what you were doing
.
you never said what monster_pos_y' is did u?
.
but what is the future value of the monster's y position?
you aim to where the moster will be given its current velocities and position
same for y
mb
yes, t is the time it takes for the projectile to go the distance to the future position of the monster
hmm
for some reason it says no solution every time
there are math domain errors (negative numbers inside sqrt) in the sqrt
should check for the discriminant first yes
like both t1 and t2 fail always for some unholy reason
the error tells you everything
discriminant = b ^ 2 - 4 * a * c
if (discriminant < 0) then error
a * t ^ 2 + b * t + c = 0
?
the quadratic you get from squaring both sides of this gives you the form
a * t ^ 2 + b * t + c = 0
the quadratic formula tells us that the discriminant (the part that is under the square root)
b ^ 2 - 4 * a * c
must be positive in order for solutions to exist
yeah but this happens every time
vary the starting conditions, check your variables
a = monster_vel_x ^ 2 + monster_vel_y ^ 2 - proj_vel ^ 2
b = 2 * (monster_vel_x * (monster_pos_x - turret_pos_x) + monster_vel_y * (monster_pos_y - turret_pos_y))
c = (monster_pos_x - turret_pos_x) ^ 2 + (monster_pos_y - turret_pos_y) ^ 2
simple case: it is impossible to hit if the monster is moving away at a speed faster than the projectile
frick it I'll go with projectiles that follow the enemy until they hit it
I tried to do this in various ways, this one, an iterative one, one where I check the coords where the monster will be and if I shoot in that direction will I hit it
thanks anyways
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Hey
I was wanting some clarification on the first 2 and I was wondering if someone could explain the last one
So for 1. Code 5
2. Code 3
Hi
And for question 3 I'm stuck at the beginning I have no idea how to start
its not code 3
find gradient of 5x-8y+12=0
What is a gradient I haven't learned that yet
in any linear equation y=mx+c m is the gradient
And why isn't it code 3
so arrange the equation in the form y=mx+c where y and x are variables whereas m and c are constants
Oh so code 4
Ok
Is it code 4
yes it is
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for the first matrix in the span
i get the 0101
and they get 1010
is it the same?
basically the answer i get has the columns switched
so x_4 is supposed to be fixed and equal to 1
yes
so I doubt the x_4 coefficient would be in the span
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Show your work, and if possible, explain where you are stuck.
its a bit messy but
x1 = a and x2 = c
but no matter how i calculate it, i get a = 0
when i chose b as 1 and c as 0
so basically x2 and x3 are free
so when calcualting the span, i chose x2 as 1 and x3 as 0
and i always get x1 = 0
but in the answers x1 = 1
nvm i goofed with the values
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Factor lhs by x_1
And divide to isole it
p_1x_1 + p_22x_1 = m
x_1 ( p_1 + 2p_2) = m
x_1 = m/( p_1 + 2*p_2)
You're suppose to factor out x1 first before dividing
It'll make it easier
Because if you divided by p1, you're dividing all the terms by that
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It'll be like this
If that makes sense
So if you divided by 2p2 then you'll have x1/p2 + x1/p1 on the left
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is there something wrong with this process?
just a lot of bad notatiion
whereabouts
and ambiguous fraction
first one is my friends soln and this one is mine
integral calculator says his is right though
are they the same? or am i wrong somewhere
they're the same
you can use a change of base
,w -(ln(2))^3/(2(ln(x))^2)=-(ln(2))/(2(log_2(x)^2))
crap
anyway
you can do
$-\frac{\ln^3(2)}{2\ln^2(x)}=-\frac{\ln(2)}{2}\left(\frac{\ln(2)}{\ln(x)}\right)^2$
Underfull \hbox (badness 10000)
then you can use change of base on the fraction on the right
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I've been having trouble with a question here
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Your question is cut off a lot
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What are the steps to solve this trig identity?
I tried it and the answer was wrong
I began to solve the left side by turning the sin^2theta into 1-cos^2theta
Let u=cos and maybe factoring will work
wdym by u=cos
Would i now subtract the 1 and the 3 like normal from the denominator
so that it becomes
-cos^2theta+3costheta-2
I'm saying instead of writing cos everywhere, write u
Factor after that numerator and denominator
Simplify and multiply by the conjugate
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ohh
i think i got it
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thanks
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solve this Differential equation
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Hey
Can someone please explain how to multiply / divide exponents that have coefficients?
I couldn't understand it
Something like $(5x^3)(7x^4)$ or $\frac{8x^2}{4x^3}$
Thanks
π£πͺπΌπ΄
note that $(bx)^n \ne bx^n$
π« Moosey π«
Yeah
but otherwise you can multiply just like ordinary numbers, recall your expontent rules as well
,tex .exp rules
π« Moosey π«
basically, as long as you don't have any addition attached, you can freely divide/multiply numbers just as you normally would
so you can just do 5*7 then apply product rule, or do product rule first, then mutliply the numbers
essentially you treat them separately
Ok I'll try