Implicit differentiation

[solemn yarrow]

Need help with part b

[errant walrus]

yummy

which paper was this

[solemn yarrow]

not sure

[errant walrus]

once you differentiate, sub in -1, -4 to work out the gradient

[lucid bronze]

Oh this fucking q it was on a mock I did

[errant walrus]

i have worked solutions on it

[solemn yarrow]

oh ok

send a pic pls

[errant walrus]

idk which paper it is 😭

[lucid bronze]

I'll try to do it myself

Then send a screenshot

[errant walrus]

nah

in doing it

let’s face

race

[lucid bronze]

Wait what answer did you get for a

To save me some time

[errant walrus]

3px^2 + qy / -qx - 6y

@solemn yarrow

q = - 5

[solemn yarrow]

yep

[errant walrus]

p = 2?

[solemn yarrow]

yeh

right

[errant walrus]

yooo

[solemn yarrow]

can i see working out

[errant walrus]

ofc

[solemn yarrow]

can you explain part b

thanks

[lucid bronze]

Damn I got beat

I also wanna see the working out wonder where the 5 marks are allocated

[errant walrus]

once you work out dy/dx you can sub in the coordinates

then work out the equation of the line

you know what the x and y coefficient is equal to

so you make the x’s and y’s wqual

last time i did this i think i had simultaneous equations

[hot radish]

Ye that’s what I got too

[errant walrus]

do you know which paper the question was from

i wanna see how i got the simultaneous equations

[hot radish]

Did you input -1,-4 into the equation?

[errant walrus]

which equation

i put it in dy/dx yeah

[hot radish]

The normal equation

[errant walrus]

yeah

[hot radish]

Yeah that’s what I did

[errant walrus]

what’d you do afterwards

[solemn yarrow]

shouldn't you input 4

[errant walrus]

hm?

you put the coordinates

(-1,-4)

[solemn yarrow]

oh

i acidentally put 4

[hot radish]

The products of the slopes is -1

[solemn yarrow]

shouldn't it be 3p +4q

because it is -q

so when you input -4

you get +4q

[errant walrus]

i got + q

they wanted the x^2 on the numerator so the only thing that should be negative is the denominator

as all the terms are positive

[errant walrus]

then you do the negative reciprocal as it’s the normal

[tardy bear]

Did u sub in the coordinates into C

[errant walrus]

i subbed the coordinates into dy/dx

[tardy bear]

U didn't have to find the equation of the tangent

[errant walrus]

if i did i could make the x and y components =

[tardy bear]

U could have rearranged the equation of the tangent in the form y = mx + c

[errant walrus]

that would’ve been faster

[tardy bear]

Yea

[errant walrus]

and less chance of error

[tardy bear]

What I was thinking u could do too is

[tardy bear]

Once u do this

U can equate the numerator to the numerator to find q

[errant walrus]

i think did that last time and got simultaneous equations actually

[tardy bear]

And then sub that into the denominator and find p

[errant walrus]

ohhh yeah

that’s a good way of doing it

[tardy bear]

But it's kinda weird

Cuz u can interpret

-19/26

[errant walrus]

true

[tardy bear]

And 19/-26

[errant walrus]

easy to make an error

[errant walrus]

yeahh ofc

[tardy bear]

Thjs will give the wrong answer

[tardy bear]

But I think u will have to interpret it as -19/26 because if u rearrange u get -19xfirst

[errant walrus]

yeah

that’s a weird way of thinking about it

if it works it works ig