how tf do you do part b

[rotund swallow]

@undone sundial please

[compact hazel]

have u done year 2 differentiation

@rotund swallow

[gaunt cedar]

Use the formula for differentiation that you get in the formula sheet

[undone sundial]

I did this yesterday I think

[undone sundial]

Yea he sitting the a levels

What u do is

U find dn /dt by using quotient rule

And then try replacing n into the Dn/dt

[gaunt cedar]

Yh that

[rotund swallow]

Yeah but they want it in terms of N

[undone sundial]

Send dn/dt

[undone sundial]

Okay soo 900/(3+7e^-0.25t)

Is N

So replace that by N

[rotund swallow]

This way is insane

[undone sundial]

I ain't reading all dat 💀

[rotund swallow]

Not even worth the 4 marks

Would just skip to part c

Also @undone sundial for part b

I got sin2x = 21/25

Which is correct

But I got 4 solutions

[undone sundial]

How

[rotund swallow]

They got 2

[rotund swallow]

Squared both sides

[undone sundial]

I would have used harmonic identity

[undone sundial]

Aighht

[undone sundial]

Ye makes sense

[rotund swallow]

Idk how I got 4 extra solutions tho

[undone sundial]

Something with ur domain

Show ur solutions

[rotund swallow]

Cos sin^-1(21/25) is 57 degrees on my calc

But that ain’t even an answer

[undone sundial]

Yea it won't be

[undone sundial]

28.5 is ?

[rotund swallow]

Nah

61.7 is the first one

Which was my second solution

[undone sundial]

Ooh aaight show me ur working out if u have done it

[rotund swallow]

Aight one sec

[undone sundial]

Ur missing a 25 I think

Ooh no wait mv

Mb

-21 I think

The RHS should be -21

[rotund swallow]

Why?

[undone sundial]

4-25

-21

[rotund swallow]

Yeah but that equals to -50sinxcosx

Can divide both sides by -1

[undone sundial]

Ooh mb

[undone sundial]

Didn't do the whole thing but 28.6 shoukd be a solution

[gaunt cedar]

Wait, Why are the integrating?

[undone sundial]

Working it the other way round

[rotund swallow]

Exactly😭

Not on the ms

[undone sundial]

Showing dn/dt = N

[undone sundial]

Hmm

Bro

OK nvm

-50 is correct

Yea bro idek why it's not

[rotund swallow]

@tranquil widget why isnt this right?

[tranquil widget]

Yea so you got 4 solutions, where 2 were in the ms

That’s because you squared it, you’ll get extraneous solitions

Where if you plugged them in, you’d get the negative version

But obv when squared they’d all equal the same answer

So doing that method, you’d need to try all your answers and see which give the positive (correct) answers and give the negative (incorrect) answers

[rotund swallow]

Wdym plug them in?

[rotund swallow]

Ohhh I see

[tranquil widget]

Into the original equation

[rotund swallow]

Ahh

Thank you sm

[tranquil widget]

So, with two of your solutions for theta, you’ll get 2

But with the other 2

They’ll give you -2

[rotund swallow]

I’ll just do harmonic from now on then

Thanks

Yeah got a negative

Ur right

[undone sundial]

Nah bro that's in the ms too

Ooh I see

[bright spoke]

is that the Rcos (x+ a) stuff?

[rotund swallow]

Yh

[bright spoke]

so which one would you use here ?

[rotund swallow]

Either works

[bright spoke]

can you send the answers as well

just wanna check if it works

nvm i just check ur answer, i got them

[rotund swallow]

2 are wrong

Read what the mentor said

[bright spoke]

yh ik i got the other 2 solutions

using the harmonic one

just wanted to see if it worked

[unreal sable]

Ok so that’s further maths a level 4 marks…

[bright spoke]

na thats normal maths

[unreal sable]

….

[quick barn]

it's normal because it's a first order differential eq

if it was second itd be fm

[unreal sable]

What even is that

[north current]

this aint gcse

op tagged it wrong

https://cdn.discordapp.com/emojis/1109192339664150559.gif?size=48&quality=lossless&name=wahhgone

[granite axle]

Isn’t differentiation part of gcse? Very simple tho like d/dx x^2

[north current]

nah it's in fm gcse

also that R symbol

[unreal sable]

It’s part of gcse I think

[north current]

differentiation isn't gcse

for edexcel at least

not in aqa

[unreal sable]

In edexcel I think it is

[north current]

not in ocr

[north current]

no

[unreal sable]

Oh igcse edexcel

[north current]

ah that might be why

yh

[granite axle]

Ye I do edexcel IGCSE and it’s a part of it

[unreal sable]

We haven’t learned it yet though

[north current]

not for us in gcse

[unreal sable]

Isn’t differentiation calculus

[north current]

yeah

[unreal sable]

Oh ok

[granite axle]

It was the last topic we did this year but it’s light at gcse

[unreal sable]

And then further igcse Edexcel is probs just harder calculus

[unreal sable]

Do you do further as well

[granite axle]

Nah my skl doesn’t offer it anymore but I’m set 1 and our teacher started teaching integration by parts

[unreal sable]

Integration?

[granite axle]

Dw abt it

It’s j the reverse of differentiation

[unreal sable]

Oh

[undone sundial]

Dw about integration 💀

Ig at a level maths it's not bad dk about fm

[granite axle]

At a level do u use integration to find arc lengths, volumes and surface areas?

[velvet plume]

Bro these differentia equations

[undone sundial]

I think that's fm if I'm not wrong

[quick barn]

a level fm

I think some of its stuck in conics