#help-27

1 messages Ā· Page 302 of 1

topaz axle
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fire is the right analogy, it's the burning embers

dry oak
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if its just dust, couldn't you just, like, wipe it off and be all good?

topaz axle
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if you remove the embers from the building, the light they gave off is not left behind

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yes

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if you spill it on the floor, you wipe it off and you;re good

dry oak
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interesting

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thank you

topaz axle
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then you have to bury the rug

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we can't stop it, we wait until it burns out

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@dry oak oh also UV from the sun is the same thing right?

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so that's confusing

dry oak
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yeaaa idk about the sun, but ive heard that it damages skin cells and can cause cancer, i tan anyway :P

topaz axle
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oh ok microwave is the opposite end, i thought it's between uv and gamma

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makes sense then

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so the left side cooks you a lot, but doesn't touch dna

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and the right side is opposite

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i guess it's like that

dry oak
# topaz axle

dang so higher frequency is basically more dangerous

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which one here is radiation?

regal moat
topaz axle
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all of this is radiation, starting from UV it's "dangerous"

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starting from X-Ray it's nuclear

regal moat
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All rays can be generated without nuclear

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Photon is a bit special

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They carry energy using a packet

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Before Enstein

dry oak
topaz axle
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they use nuclear decay

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maybe not always

regal moat
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Photoelectric effect is unexplainable

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People thought photon energy derive from intensity

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But its frequency

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Its a long paper

topaz axle
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@dry oakalso nuclear bombs do all of this, and the goal is to make the left side radiation, one that cooks

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the "dangerous" side is pointless

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just can;t avoid it

regal moat
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Nope

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Pretty sure a bunker build underground from steel (for support) and lead (for shielding) can stop the gamma ray

dry oak
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water can stop radiation too right? hence the blue light effect

regal moat
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You want dense material like lead and tungsten or depleted uranium

topaz axle
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can't avoid producing it i meant

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i started doubting that it's insignificant in total energy

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but seems true, it's less than a third at least

dire forge
# dry oak huh? dont we get xray in hospitals šŸ‘€

The X-rays you get in a hospital are called hard X-rays, and they're more on the right of that image, so they're more energetic. Because of how energetic they are, X-rays can give you increased risk for cancer, if they are absorbed by DNA and cause mutations. But for medical use, X-rays are generally very controlled and you are only exposed to them for a very short amount of time. Generally, if you are in need of getting an X-ray, the benefits of getting the X-ray and being able to get a medical diagnosis and treatment outweigh the potential risks. X-rays generally come from electrons, not the nucleus of an atom. This happens when an electron jumps down from a higher energy level to a lower one, releasing the energy in the form of a photon. The nucleus of an atom generally emits gamma rays, which are even more energetic.

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For the discovery of X rays, the physicist Rƶntgen was awarded the first Nobel Prize in Physics

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But yes, everything from radio waves to microwaves to the light you see to X-rays operates under the same principle. The only difference is the frequency of the radiation, which changes how much energy each photon has. This form of radiation is called "electromagnetic" radiation because it travels as a wave through the electromagnetic field.

devout snowBOT
#

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finite briar
#

could someone verify (numerically) if $$\psi \left(\frac{2n+1}{4} \right) - \psi \left(\frac{2n+3}{4} \right) = \Phi \left(-1, 1 \frac{2n+3}{4} \right)$$? Here $\psi$ is the digamma function and $\Phi$ is the lerch transcendant

woven radishBOT
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rak³en

finite briar
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Okay nvm seems false

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yeah def false

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chat could yall help me with this

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I used the fact $\psi(z) = \gamma + \int_0^1 \frac{1-t^z}{1-t}dt$

woven radishBOT
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rak³en

finite briar
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so basically that means $$\psi \left(\frac{2n+1}{4} \right) - \psi \left(\frac{2n+3}{4} \right) = \int_{0}^{1} \frac{ t^{\frac{2n+3}{4}} - t^{\frac{2n+1}{4}} }{1-t} dt$

slender mirage
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At n = 1, LHS is pi - 4, rhs is thisnt

woven radishBOT
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rak³en
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

finite briar
finite briar
finite briar
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thx

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.close

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finite briar
#

.reopen

devout snowBOT
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āœ…

slender mirage
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blunder returns

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Hey kannawave

finite briar
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Hey lol

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Tf isn't the imaging going

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is this correct?

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also assume first line is 100% correct

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also i think the mistake is when i switch the sum and the integral

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(done by fubinis theorem, but i never check the conditions xd)

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pretty sure its simply convergence though, which it should

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HMMMMMMMMMMMM

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OKAY so I am getting

woven radishBOT
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rak³en

finite briar
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Where in reality it is

woven radishBOT
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rak³en

finite briar
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<@&286206848099549185>

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oops missed a comma in both latex

slender mirage
sage burrow
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hmmm did you miis the change from 1/2 to 1/4?

slender mirage
finite briar
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oh yeah lol right i missed wayy too much

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1 sec lemme re latex

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got $\psi \left( \frac{2n+3}{4} \right) - \psi \left( \frac{2n+1}{4} \right) = 2\Phi \left(-1,1, \frac{2n+5}{2} \right)$, but supposed to be $\psi \left( \frac{2n+3}{4} \right) - \psi \left( \frac{2n+1}{4} \right) = 2\Phi \left(-1,1, \frac{2n+1}{2} \right)$

woven radishBOT
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rak³en

finite briar
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And I can't spot the mistake 😐

finite briar
# finite briar

the mistake shouldnt be after this page, because all I did was simply write it as a lerch transcendant on the next page

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also I gtg for a bath so yall if someone finds the mistake pls do share it

devout snowBOT
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@finite briar Has your question been resolved?

slender mirage
devout snowBOT
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slender mirage
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.reopen

devout snowBOT
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āœ…

slender mirage
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$\psi(z) = - \gamma + \int_0^1 \left(\frac{1-t^{z-1}}{1-t}\right) \dd t$

woven radishBOT
slender mirage
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is the right formula. what you're using has {z} in place of {z - 1} in the integral @finite briar

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that is shifting your Lerch transcendent's a by 2

devout snowBOT
#

@finite briar Has your question been resolved?

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daring barn
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Hi, when doing data normalization, how do we choose between max-normalization or min-max normalization?

devout snowBOT
#

@daring barn Has your question been resolved?

devout snowBOT
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@daring barn Has your question been resolved?

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viral lynx
devout snowBOT
viral lynx
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I drew a lil diagram sorry its not the best

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The equation of the circle is (x+1)^2 + (y+2)^2 = 9

fossil locust
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what did you get as the radius of the circle?

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oh cool

viral lynx
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r = 3

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Im not really sure how to solve it though

fossil locust
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a few different approaches exist

viral lynx
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We dont have either the x or y coordinate of the tangent

fossil locust
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I would recommend subbing in y = ax + b, expanding and rearranging to get a quadratic in x

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then you can use the fact you need discriminant = b^2 - 4ac = 0

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since you only want 1 x-value, for 1 intersection -> tangent

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and also -2 = a * 11 + b, so you have -2 - 11a = b

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so you really just have a quadratic in x, and a as some unknown constant

viral lynx
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1 moment im rereading a few times to try and understand

viral lynx
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Where do these numbers come from?

fossil locust
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you sub (x, y) = (11, -2) into y = ax + b

viral lynx
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Ahh

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Alright I will try

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(x + 1)^2 + (y + 2)^2 = 9

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(x + 1)^2 + ((mx + c) + 2)^2 = 9

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x^2 + 2x + 1 + (mx + c + 2)^2 - 9 = 0

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(mx + c + 2)^2 is really really messy šŸ˜µā€šŸ’«

ebon coyote
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( ... = 0 at the end there)

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Yh it'll be a little

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Treat it as ( [mx] + [c + 2] )^2

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(because it will sort out your x-powers for you)

viral lynx
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Can I sub in the -2 and 11 now? That would make things easier

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Or is it too early?

viral lynx
fossil locust
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yeah actually that's easier now

viral lynx
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Ok thank god šŸ˜…

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x^2 + 2x + 1 + (mx + c + 2)^2 - 9 = 0

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x^2 + 2x + 1 + (mx - 2 - 11m + 2)^2 - 9 = 0

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x^2 + 2x + 1 + (mx - 11m)^2 - 9 = 0

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x^2 + 2x - 8 + (m^2)(x^2) - 22xm^2 + 121m^2 = 0

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Actually im not sure

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What is a, b and c in b^2 -4ac

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Do I get a = 1 from x^2? Or is it a = m^2 because of the (m^2)(x^2)?

viral lynx
fossil locust
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also you mean -22xm^2

viral lynx
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I think thats the part im stuck on

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Like is x^2 the only x^2 term or is (m^2)(x^2) also an x^2 term

fossil locust
viral lynx
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Ah ok

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Ahhh I see what I need to do

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x^2 + 2x - 8 + (m^2)(x^2) - 22xm^2 + 121m^2 = 0

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(1 + m^2) x^2 + (2 - 22m^2) x + (-8 + 121m^2)

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So a = (1 + m^2)
b = (2 - 22m^2)
c = (-8 + 121m^2)

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b^2 - 4ac = 0

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(2 - 22m^2)^2 - 4(1 + m^2)(-8 + 121m^2) = 0

fossil locust
#

try substituting m^2 = u by the way

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makes your life easier

viral lynx
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4 - 88m^2 + (- 4 - 4m^2)(-8 + 121m^2) = 0

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4 - 88u + (- 4 - 4u)(-8 + 121u) = 0

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4 - 88u - 484u^2 - 452u + 32 = 0

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-484u^2 -540u + 36 = 0

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-4(121u^2 + 135u - 9) = 0

fossil locust
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yeah hold on

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(2 - 22m^2)^2 = 4 - 88m^2 + (-22m^2)^2
= 4 - 88u + 484u^2

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so you actually just get 4 - 88u - 452u + 32 = 0, everything else is right

viral lynx
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4 - 88u + 484u^2 - 452u + 32 = 0

fossil locust
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no, you are missing +484u^2

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so if you add it back you get 4 - 88u - 484u^2 - 452u + 32 + 484u^2 = 0

viral lynx
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Ohhh

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I thought you meant my sign was wrong haha

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Okok I see

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4 - 88u - 484u^2 - 452u + 32 + 484u^2 = 0

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36 - 540u = 0

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540u = 36

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u = 36/540

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u = 1/15

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m^2 = 1/15

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m = +-sqrt(1/15)

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Those are the slopes of the tangents

fossil locust
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yeah

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you just need one of the tangents so you can choose say m = sqrt(1/15)

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also remember from the very beginning, -2 - 11m = c

viral lynx
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For a min i forgot what the original question was šŸ˜…

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So many u's and m^2's

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but ok

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-2 - 11m = c

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-2 - 11(sqrt(1/15)) = c

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Cant simplify that

fossil locust
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yeah just leave it then

viral lynx
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so c = -11sqrt(1/15) - 2

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The final equation is

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x/15 -11sqrt(1/15) - 2

fossil locust
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you mean, x/sqrt(15) - 11sqrt(1/15) - 2

viral lynx
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Ah yeye

fossil locust
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could you simplify something like tan(arcsin(u)) using a right triangle?

viral lynx
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🤩

viral lynx
fossil locust
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I have a quicker way if you know that, cause this question is quite specific

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the centre happens to lie on the same horizontal line as (11, -2)

fossil locust
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okay then don't worry about it

viral lynx
fossil locust
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yeah, it's actually not that bad

viral lynx
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Could you teach me? If you dont mind

fossil locust
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if theta = arcsin(u), then sin(theta) = u

so you can let opposite = u and hypotenuse = 1
so adjacent = sqrt(1 - u^2)

and tan(theta) = u/sqrt(1 - u^2)

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for this question u happens to be 3/12 = 1/4

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tan(theta) = sin(theta)/cos(theta) = y/x

so that gives you the slope of a line

viral lynx
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Ok 1 moment I need to reread that a few times to understand

fossil locust
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when you're ready

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,w 3/sqrt(12^2-3^2)

fossil locust
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,w 1/sqrt(15)

viral lynx
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Ah cool

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That is actually a really neat way of doing it

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I thiiiiiiiiiink I get it but im gonna do some more examples with this method to make sure I do

fossil locust
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yeah then the identity follows if you replace 3 with u, and 12 with 1

so that sin theta = opp/adj = u/1 = u

viral lynx
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Ah yeye I think I get it

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My brain is fried after this question so Im gonna take a quick break before I try some more examples hehe

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But thank you sooooo much for your help

fossil locust
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no worries!

viral lynx
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You are a really good teacher!!

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ā¤ļø

#

.close

devout snowBOT
#
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native stone
devout snowBOT
native stone
#

so we got this exercise, dont mind the different language because ill show my solution so that should help

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thing is, i came up with a solution, got to the right answer....but the solution has a flaw in it that actually makes me wonder why it works

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at the top of the page i put what we know so that its easier to understand

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the problem here, is that i amplified with z-|z|

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so multiplied and divided

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which we dont know if its zero or not

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because if it zero, then i couldnt do that

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one of the multiple choice actually even sais that z=1 so it was a possibility

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anyone got a clue why this works?

frozen aurora
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if $\overline{z} \neq -|z|$ then $z \neq -|z|$ as well

woven radishBOT
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artemetra

frozen aurora
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because |z| is real

native stone
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why

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oh

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thats cool, thanks

slender mirage
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You have to check, for which z, you have Im(z² + 2z|z|) = 0

native stone
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it sais that z is complex

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so for no z

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or wait

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idk what you wrote there honestly

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but it makes sense that z is different that |z|

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since one is complex and one is real

thin inlet
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|z| not equal z conjugate implies z is not purely real

native stone
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oh

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so then how do i show that z-|z| is different than 0

thin inlet
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or wait

slender mirage
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The conditions should be Im(z) = 0 or Re(z) + |z| = 0

native stone
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ill show you a pic of what i got

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which is wrong

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here

slender mirage
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No need to over complicate

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Since it says w is real, multiply num, denom with (z + |z|)

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(z{bar} + |z|)(z + |z|) is now real

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So, (z + |z|)² is real

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=> z² + 2z|z| is real

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Plug z = a + ib, and you have your conditions, 2ab + 2b|z| = 0

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So, b = 0 or a + |z| = 0

native stone
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i dont understand what youre saying by multiply with denom conjugate

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like, z conj - |z|?

slender mirage
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multiply num, denom with (z + |z|)

native stone
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how do you know that thats different than 0

slender mirage
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huh? what is different than zero

native stone
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z+|z|

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how do you know its diff zero

slender mirage
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z{bar} + |z| non zero is given

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so its conjugate is also non zero

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wdym

native stone
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wdum ,,its,, conjugate

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the conjugate of the sum?

slender mirage
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YES

native stone
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whats the conjugate of a sum

slender mirage
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bruh blobcry

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conjugate of z1 + z2 = conjugate of z1 + conjugate of z2

native stone
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wow

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oki

slender mirage
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now which option says Im(z) = 0, or Re(z) + |z| = 0

native stone
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if im(z)=0 doesnt that just mean that z is real?

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just hold on until i write it down, i may have some more questions if i dont get something

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what do i do now

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@slender mirage

slender mirage
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BRUH

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Don't you think you're over indulgent with your FOILS?

native stone
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foils?

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huh?

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whats that?

slender mirage
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basically, multiplying algebraic expressions and expanding

native stone
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how would you do it otherwise?

slender mirage
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It's like I give you (a + b)(b + c)(c + a) and you expand it all the way to get 2abc + ...

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=_= I never told you to expand denominator

native stone
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what are you supposed ot do?

slender mirage
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NO, not when it's not required

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but you will =_=

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we multiplied denominator with its conjugate because

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For any complex number w, ww{bar} = |w|² is real

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So denominator is real even if you do not multiply and expand

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Got it?

native stone
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NO

slender mirage
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=_=

native stone
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all this time

slender mirage
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the denom is (z{bar} + |z|) yes?

native stone
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you meant to multiply w*w conj?

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is that what u wanted?

slender mirage
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YEAH

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wait no

native stone
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i feel violent

slender mirage
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no no lmao

native stone
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good

slender mirage
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it's not w wconj

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jeez

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I ran out of variables

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is why I used w

native stone
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brother, what do you want me to do

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i dont understand

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shouldnt i have multiplied how i just did/

slender mirage
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Alright let's do from step 1

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Okay?

native stone
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sure

slender mirage
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denom is (z{bar} + |z|) yes?

native stone
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damn right

slender mirage
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(z + |z|) is its conjugate yes?

native stone
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hell yea

slender mirage
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so we multiply num and denom with (z + |z|)

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alr?

native stone
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no no

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we dont

slender mirage
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=_=

native stone
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im kidding

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keep going

slender mirage
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so the denom automatically becomes real, yes?

native stone
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wow

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i didnt see it that way

slender mirage
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Yes. No?

native stone
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yeye

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i see it now

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so now we got the num which we should show it real

slender mirage
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Yes

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And num is (z + |z|)²

native stone
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damn

slender mirage
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so we gotta have z² + 2z|z| as real

native stone
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and |z| is real

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wait

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oh yea i see

slender mirage
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plug z = a + ib

native stone
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i thought that if (z+|z|)^2 is real then z+|z| is also real

slender mirage
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we need Im(z² + 2z|z|) = 2ab + 2b|z| = 0

native stone
slender mirage
native stone
#

im tempted to just literally see what (a+bi)^2 is

slender mirage
#

you only need the imaginary part blobcry

native stone
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and then substitute in z as well

slender mirage
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Yes that is what I did bleakkekw

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picked the imaginary part from the expression after substitution

native stone
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right right

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so you did do the ,,foil,, or whatever

slender mirage
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did not -_-

native stone
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so you would get 2b(a+|z|)=0

slender mirage
#

Yes

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So either b = 0, or a + |z| = 0 which converts to b = 0, a < 0

native stone
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why

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cant a= -|z|?

slender mirage
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Yes lol, solve that equation now

native stone
slender mirage
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what is |z|

native stone
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oh

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b=0 in that case too

slender mirage
#

āœ…

native stone
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sensational

slender mirage
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so z is compulsorily real,

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not necessarily < 0 tho

native stone
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this was way harder than i thought

slender mirage
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which we could've just guessed by putting numbers

native stone
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thought itd be easy peasy

slender mirage
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=_= which part of what I showed you was hard

native stone
native stone
#

im reminding you that im recapping for an exam rn

slender mirage
native stone
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so thats why i forgot some things

slender mirage
#

those problems are called no brainers

native stone
slender mirage
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unfortunately blobcry there's not many no brainer problem up here

native stone
#

well

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you probably dont have multiple choice problems

devout snowBOT
#

@native stone Has your question been resolved?

#
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regal berry
#

$(-4)^{73} / 2^{144} - 25^{12} / 5^{23}$ idk how to start

woven radishBOT
#

Simon James B

regal berry
#

$(-2^2)^{73} / 2^{144} - (5^2)^{12} / 5^{23}$ like this?

woven radishBOT
#

Simon James B

regal berry
#

but from here i am stuck

toxic grove
#

Try expanding out the brackets

small jackal
#

4^evennumber = (-4)^evennumber

#

Same with 2

#

Simplify the right side first

regal berry
#

so it's -(2^2)^73

#

sorry but i am confused

toxic grove
small jackal
toxic grove
#

$(a^b)^c = a^{bc}$

#

That should be enough

#

with proper formatting though lol

small jackal
toxic grove
#

ukwim

#

It's still -4^oddnumber though

#

The - does not cancel o ut

regal berry
#

still confused on what to od

woven radishBOT
#

depression

regal berry
#

I know! But is this the easiest way? we are supposed to do to the easiest

toxic grove
#

That is the easiest way

small jackal
#

Okay I just re-read

toxic grove
#

Just simplify it down and the answer will fall out

small jackal
#

-4^73=4^72 x -4

#

2^144=4^72

regal berry
#

$-2^{146} / 2^{144} - 5^{60} / 5^{23}$

woven radishBOT
#

Simon James B

toxic grove
#

Might wanna check that arithmetic

#

But yeah that's the right idea

small jackal
regal berry
#

but we do not have the same base how do i make 2 negative

small jackal
#

-(2^146)=-2x2^145

regal berry
#

or it does not matter

small jackal
toxic grove
#

It both matters and doesn't matter

#

You already solved it without realizing I think

small jackal
toxic grove
#

The minus sign is effectively outside the brackets

#

So yeah just forget about that

small jackal
regal berry
#

$-2^2 -5^{37}$

toxic grove
woven radishBOT
#

Simon James B

small jackal
#

Check the right side

regal berry
#

ok lemme do it again

#

$(-2^2)^{73} - (5^2)^{12} / 5^{23}$

woven radishBOT
#

Simon James B

small jackal
#

No just evaluate the right side

regal berry
#

omg-

#

what is there to evalute

#

i can't see

toxic grove
#

How did you work out 5^37

small jackal
regal berry
small jackal
#

Do this first $(5^2)^{12}$

woven radishBOT
regal berry
#

5^24

small jackal
#

Yes so 5^24/5^23=...

regal berry
#

5

small jackal
#

So what is your final answer

regal berry
#

-5?

small jackal
#

Now put that together with your answer for the left.

regal berry
#

hold on cuz idk what is the answer from the lest side

small jackal
#

Ping me when you're ready

regal berry
#

-4-5 = -9

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regal berry
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small jackal
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small jackal
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vast violet
#

pls...

devout snowBOT
vast violet
#

i am just annoyed and ready to smash tjis calcukator

tropic skiff
vast violet
#

ok

viscid onyx
#

That's in radians.
Convert it into degrees.

tropic skiff
#

And in the 4th row, change to DEGREE instead of RADIAN

vast violet
#

Ohh ok thnx

#

so i should keep it there for a physics class

tropic skiff
vast violet
#

Ok thnxs

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hasty flame
#

does a polynomial like f(x) = (x+1)^2 (x-2)^2 have a vertex when graphed?

distant helm
#

From the given function there are definitely 3 vertex

#

2 lies on x-axis which are zeros of the function and 1 above x-axis

ancient sluice
#

x< -1 fn , x (-1,2) fn , x >2 fn

hasty flame
smoky nimbus
distant helm
#

You can expand f(x) and solve f'(x)=0 which instantly gives 3 critical points

hasty flame
hasty flame
distant helm
#

But in this case its unnecessary because you can guess how many vertex

distant helm
distant helm
#

Double roots act as vertex because f(x) doesnt change sign through those points

hasty flame
#

expand the function

distant helm
#

Ye, expand, solve f'=0

hasty flame
#

whats that little ' for?

distant helm
#

f'(x)=0, to be more clear

smoky nimbus
hasty flame
#

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stray orbit
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stray orbit
#

not even sure what the u is here imma be honest

#

Very lost

faint gorge
#

maybe 2tan(theta)

#

for x

stray orbit
#

What?

potent tusk
#

how does bro see this

stray orbit
#

😭😭😭

faint gorge
#

or maybe trig sub won't work

#

nicely

potent tusk
#

why cant you use usub

stray orbit
#

I have not learned of any such trig sub yet

stray orbit
faint gorge
#

the next thing that came into mind would be u = x² that would cancel an x

#

and then another linear substitution with u+4

stray orbit
#

Bro what is linear substitution

#

I just started Calc 2 bro šŸ˜–šŸ˜–šŸ˜–

#

I can only use u sub

faint gorge
#

when you substitute something in the form of ax+b

#

that's also u-sub lol

#

just a fancy name

stray orbit
#

Oh

faint gorge
#

yea try u = x²

stray orbit
#

I assumed it was some crazy bs idk

faint gorge
#

no dw

#

and then do z = u+4

#

step by step should get you to work

#

it out

stray orbit
faint gorge
#

did you first apply the u-sub

stray orbit
#

Am rn

#

Ngl bro he did not prepare us for a lot of the questions on this hw

#

How are they assigning this after 1 lecture

stray orbit
faint gorge
#

you forgot the dx and to change that into du

woven radishBOT
#

anti-algebraist š”ødωnš“²Ā²s

faint gorge
#

And then another "u-sub" let's call it z and that will be z = u+4

#

and then use power rule

stray orbit
#

Where does the * 1/2x come from

faint gorge
#

differentiate u = x^2

stray orbit
faint gorge
#

du/dx = 2x

#

dx = 1/(2x)

faint gorge
#

you could have done u = x²+4 too but I was afraid that would be too much at first

#

anyway gtg u will figure it hopefully

stray orbit
faint gorge
#

same

#

it's the very same procedure

#

rewrite everything in terms of u and change dx in terms of du

stray orbit
#

.close

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velvet bear
#

can i get some help solving this

devout snowBOT
wicked turtle
#

!status

devout snowBOT
#
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2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
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7. None of the above
velvet bear
#

1

wicked turtle
#

what have you tried?

velvet bear
#

i really dont even know where to start so nothing yet

strange nimbus
#

What can you do to the left side to get just s by itself?

velvet bear
#

wait i think i know what to do now thanks for the help

#

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strange nimbus
#

No problem.

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rugged crypt
devout snowBOT
devout snowBOT
# rugged crypt
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
rugged crypt
#

1

winter torrent
#

draw a sketch

rugged crypt
#

how?

winter torrent
#

well you could start by getting a pencil and some paper...

#

I see an equation. is it in a standard form that you recognize?

#

if not, can you put it into one?

#

it says ellipse. is there something in your book or notes about an ellipse?

rugged crypt
#

wanted to confirm this is the sketch

winter torrent
#

I mean it's a graph so sure

rugged crypt
#

tbh i dont really know much bout how to solve these types of word problems

#

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burnt leaf
devout snowBOT
burnt leaf
#

For Calculus 2, how do I get the volume for this ? I'm honestly very confused and don't know how to do it on paper.

burnt leaf
#

Kinda, it's using the area of the circle as the first step, right?

wind mason
#

$\int_a^b \pi (r(x))^2dx$ or in terms of $y$, where $r(x)$ or $r(y)$ is the radius function.

woven radishBOT
wind mason
#

but here, there is 2 radii.

burnt leaf
#

So for x, it'd be pi (x^2)? then y, pi (y^2)?

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#

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#

@burnt leaf Has your question been resolved?

burnt leaf
#

.reopen

#

.close

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burnt leaf
#

.reopen

devout snowBOT
#

āœ…

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hazy cradle
devout snowBOT
hazy cradle
#

i made a GP like:
a/r^3, a/r^2, a/r, a, ar, ar^2, ar^3, ar^4

#

3rd * 5th = a^2 = 49 => a=7

#

nvm

#

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hazy cradle
#

.reopen

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#

āœ…

hazy cradle
#

idk how to solve

#

what i tried :
took b as the common diff, a as the first term, thought of it like an AP

#

but idts im going anywhere with that

toxic grove
#

You should start by calculating m

#

There's quite a limited number of values for a and b to try so it shouldn't take long to just count the elements of R

hazy cradle
#

wont that waste time, if i try finding it by counting?

feral agate
#

anything beyond n=3 results in 0

#

so if m >= 3 you only need to go upto n=3

#

ah wait you still need m though

#

yeah you just need to count then

hazy cradle
#

lemme try

#

m=8?

feral agate
#

yes

hazy cradle
#

oo i got it

#

i hv one more ques

distant helm
#

I think you can use binary here? not sure but give it a try

hazy cradle
#

what is binary?

distant helm
#

yeah no that is too overkill

#

you can simply determine the row by trial and error
(if you notice that you can determine the first and final number of the row)

#

for example, to know 8 is in what row, guess that 8 is in-between 7 and 10

#

the first and final numbers of a row also have a formula that is easy to derive

solar goblet
#

what i would recommend is to write the upper and lower bound of a row as a formula of k

#

notice that the lowerbound for each row is 1, 2, 4, 7, 11, ...

#

1 + 0 = 1
1 + 1 = 2
2 + 2 = 4
4 + 3 = 7
7 + 4 = 11

#

one can see that as the pattern continues, the second term increments. thus this is a quadratic trend

#

likewise for the upperbound

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slender mirage
# hazy cradle
Now, solving the recursive relation gives L(n) = n(n+1)/2.
Also, the start term of nth row is nothing but L(n - 1) + 1```
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hazy cradle
slender mirage
#

let's check

#

,calc 103*104/2

woven radishBOT
#

Result:

5356
slender mirage
#

looks like it does contain 5310. Congratulations

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hazy cradle
#

yeah ggs

#

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restive river
devout snowBOT
restive river
#

need to write the negation of this

#

i.e f is not increasing smth

#

My attempt

#

f is not increasing if $f(x) \geq f(y)$ for some x,y such that $x<y$

solar goblet
restive river
#

hehe

#

sorry

distant helm
#

equal also works

#

obviously

solar goblet
#

negation of < is not >

restive river
#

i forgot the difference between increasing and strictly increasing

#

so wasnt sure if i had to include equals to

dark tundra
#

They’re the same

solar goblet
#

they are the same

slender mirage
#

basically, you're given p -> (q -> r)

#

can you write it's negation thinkies

dark tundra
#

There is a difference between increasing and nondecreasing

stone stump
#

be careful

#

this very much depends on the author

steady robin
#

i thought increasing was >= strict increasing was >

stone stump
#

for me increasing and strictly increasing are different

steady robin
solar goblet
#

i guess 1 2 3 3 4 is increasing but not strictly increasing

steady robin
solar goblet
#

but it seems like the question writer doesn't bother to make a distinction between the two

dark tundra
# restive river

Well either way the given definition of increasing in this question is f(x) is strictly less than f(y) for x<y

#

So what is the negation?

steady robin
#

the distinction is important
f(x) < f(y) whenever x < y implies increasing but the converse is not true

woven radishBOT
restive river
#

šŸ‘ ?

dark tundra
#

In this case, yes

steady robin
#

idk who put that i think it was arya but this

slender mirage
#

it was OP making changes to their latex

steady robin
#

oh

slender mirage
#

if you're required to entirely negate it, should look like:
||f is an increasing function and there exists x < y such that f(x) ≄ f(y)||

restive river
#

i should have posted the complete question :P

slender mirage
#

however, I think you want something different

restive river
#

ii

slender mirage
#

:p

slender mirage
#

:p I assumed you wanted to negate the whole statement, turns out it only requires you to negate the increasing property

restive river
#

yeah

#

arent both the same?

slender mirage
#

No lmao, one is ¬(p -> (q -> r)) other is ¬p -> ¬(q -> r)

#

they're not the same

restive river
#

damn

#

ah

slender mirage
#

So basically, what you wish to express is: \ f is not increasing if $\exists x, y,$ s.t. $x < y$ and $f(x) \geq f(y)$

woven radishBOT
restive river
#

s.t ?

slender mirage
#

such that

#

it's same anyways, you can use your wordings

restive river
#

thanks

slender mirage
#

^^" next time present original q before interpretation

#

helps

restive river
#

¬(p -> (q -> r)) is the same as p -> (q -> ¬r)) ?

#

@slender mirage

slender mirage
#

nope

restive river
#

whats ¬(p -> q) ?

#

p -> ¬q right ?

slender mirage
#

¬(p -> q) is p and ¬q, p -> ¬q is ¬p or ¬q

#

are they both same?

restive river
#

i should make a truth table to check that right?

slender mirage
#

or simplify, it's easy to do that

restive river
#

simplify ?

#

oh

#

p and (q and ¬r))

slender mirage
#

šŸ’€

restive river
#

lol

#

thats rigged

slender mirage
#

Lmao, you should get back on topic

#

I need to go too. I'm running late on my Curves n Surfaces assignment

restive river
#

okay

#

thanks

#

.close

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#
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pseudo pollen
#

A password contains the digits 0,1,...,9 with no restrictions, except it has to have at least two and at most four digits. Also, the password must contain an 8. How many possible passwords are there?

topaz axle
#

you solve it three times

#

2 digit, 3-digit, 4-digit

pseudo pollen
#

I did

#

and I got 2386

#

is it right?

topaz axle
#

no i get much more

pseudo pollen
#

how much šŸ’€

topaz axle
#

how much did you get

#

separately

pseudo pollen
#

from 10 to 99 18 numbers

#

From 100 to 999 252

topaz axle
#

18 is right, 19 with 00

#

3 digit is 271

arctic field
#

why are you doing 10 to 99?

#

its a password it doesnt have to be a number

pseudo pollen
#

wdym

topaz axle
#

oh yeah, it's jsut a conicnidence

pseudo pollen
#

wait so it’s much higher

topaz axle
#

like you missed 10 paswrods and found 9 extra

pseudo pollen
#

wait a sec

#

but wdym I missed 10 passwords?

topaz axle
#

well you started from 10, there are 10 passwords less than 10 i forgot about 8 facepalm

#

but you still got 18 anyway

#

the right number is 19

pseudo pollen
#

okay

#

but for example, from 100 to 199 there are 19 numbers right?

#

and from 800 to 899 there are 100

#

and from 200,300,400,500,600,700 and 900 there are also 19 numbers for each of them

#

so

#

isn’t it 19*8+100?

#

or am I missing something

topaz axle
#

now you're missing 19 from 000 to 099

arctic field
#

008 is valid

pseudo pollen
#

o

#

oh

#

wait so

#

there are also numbers like 0008?

topaz axle
#

sure

arctic field
#

its a password, not a number

pseudo pollen
#

oh

topaz axle
#

that's why they said no restrictions

pseudo pollen
#

that makes sense

#

can I dm you when I’m done?

topaz axle
#

there's like no other restriction they meant

#

i don't mind

pseudo pollen
#

ohh

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#

@pseudo pollen Has your question been resolved?

pseudo pollen
#

ok final answer 3729

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proven canyon
#

My book tells me that a function such as the one on the upper part of the image cannot have a primitive function because of darboux's theorem.
However could a function such as the one on the bottom have one?
Thanks in advance

proven canyon
#

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spring gate
#

any idea on how to integrate this

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faint prawn
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Let r2 + x2 = u

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2xdx = du

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Then you can do it i think

spring gate
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lemme try

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wont it come like this

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nah it seems way too complecated

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ther's gotta be a better method

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ight lemme try soemthing

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woven radishBOT
#

rak³en

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finite briar
#

BRUH

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lost laurel
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lost laurel
#

Kind of confused as to How I'd sketch this

winter torrent
finite briar
#

jacobian ded

winter torrent
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it's pretty simple to see the region 1 ≤ u ≤ 2

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the region 1 ≤ uv ≤ 2 is a little harder but still very doable

lost laurel
#

Oh, I thought one of the axes was a hyperbola here 🤦

lost laurel
winter torrent
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sure seems good

lost laurel
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Thanks

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.clopse

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lost laurel
#

Evaluate $\int \int_{S} x^2 y^2 dy$ where it's bounded by $y=0, y=x, x+y=1$

lost laurel
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I intend to use a change of variable

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I was thinking $ y= v, 1-x=u$

woven radishBOT
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What a wonderful world!

lost laurel
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So like the integral before I change the order would be

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$\int_{0}^{0.5} \int_{y}^{1-y} x^2y^2 dx dy$

cinder bobcat
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I think you mean y to 1-y right?

lost laurel
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oops

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yeah

cinder bobcat
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and do you have to use a change of variable?

lost laurel
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Yes

cinder bobcat
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oof

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okay well what's your next step then

woven radishBOT
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What a wonderful world!

lost laurel
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so now y=v

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and x=u?

cinder bobcat
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well you said the transformation was y = v, x = 1-u if you move stuff around

cinder bobcat
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yeah, best thing to do is graph the transformation

lost laurel
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I am

cinder bobcat
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you kinda have to in order to know the new bounds

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oh good

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oh I gotta go for now sorry, hopefully someone else can help or you can finish it off 🫔

lost laurel
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Thanks

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I feel like the bounds don't chnage at all

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<@&286206848099549185>

faint gorge
lost laurel
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what should it be

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,w y=0, y=x, x+y=1

faint gorge
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I think 0 to 1

lost laurel
faint gorge
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isn't that the region?

lost laurel
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oops

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my bad

faint gorge
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no my bad

lost laurel
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yea

faint gorge
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you are right

lost laurel
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I

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I'll use horizontal lines to integrate

faint gorge
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now what's the sub you plan to do

lost laurel
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so is $\int_{0}^{0.5} \int_{y}^{1-y} x^2y^2 dx dy$ fine?

woven radishBOT
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What a wonderful world!

faint gorge
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yea

lost laurel
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then y = v , x= u

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wait no

faint gorge
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this wont do anything

lost laurel
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yeah

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Any suggestions

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Maybe x+y=u,, x-y=v

faint gorge
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maybe u = x² and v = y²

lost laurel
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hmm

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yeah

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that works

faint gorge
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if think anything else would make it worse than it is

lost laurel
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So I now have $\int_{0}^{0.25} \int_{\sqrt{v}}^{1- \sqrt{v}} uv du dv$

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ooops

woven radishBOT
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What a wonderful world!

lost laurel
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Is that right

faint gorge
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I think the jaboian is missing

lost laurel
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oh right

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I can manage that

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is it fine other than that

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I want to ensure I know how to change the limits easily

faint gorge
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the bounds for u might be off

lost laurel
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Hmm?

faint gorge
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x = (1-y) and x² = u
So u = (1-y)² = (1-sqrt(v))²
and for lower x = y then x² = y² = v

lost laurel
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yea

faint gorge
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I feel this sub made things worse lol

lost laurel
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Let me check if my book suggests any subs

faint gorge
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[ \int_{0}^{0.25} \int_{v}^{(1- \sqrt{v})^2} uv \cdot \abs{J} : du dv ]

woven radishBOT
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anti-algebraist š”ødωnš“²Ā²s

lost laurel
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It suggets x=u+v, y=u-v

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my book

faint gorge
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ok then let's do that

lost laurel
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so $u= \frac{x+y}{2}; v= \frac{x-y}{2}$

woven radishBOT
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What a wonderful world!

faint gorge
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ok

lost laurel
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hmm

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hmm

lost laurel
faint gorge
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y in [0, 0.5] and x in [y, 1-y]

lost laurel
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no, no

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I mean

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How do I do the substitution now

faint gorge
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x²y² = (u+v)²(u-v)²

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then you'd need the Jacobian

lost laurel
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Yeah, trying to sketch the region though

faint gorge
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I think you need to get the intersections

lost laurel
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yeah, trying to figure that out

faint gorge
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and then plug them into your substitution and draw the new intersections in the uv plane

lost laurel
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wait

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so I have x=u+v

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and y = u-v

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one boundary is x=y

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so u+v=u-v

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so v=0

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another boundary is 1-y=x

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so 1-(u-v)= u+v

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so 1-u+v=u+v

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which gives be u=1/2

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which is very sus

faint gorge
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The new points are (0,0), (0,0.5) and (0.5,0.5)

lost laurel
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How did you get that

faint gorge
lost laurel
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What I did was,

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uh

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x=y

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so u+v=u-v

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so v=0

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then $u+v=1-(u-v) \implies u+v= v+1-u$

woven radishBOT
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What a wonderful world!

lost laurel
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so u=1/2

faint gorge
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ok

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continue

lost laurel
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and then

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uh

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u-v=0.5

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so the points I',m getting are (0,0), (0.5,0.5), (0.5,0)

faint gorge
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(u,v) or (v,u)?