Algebra, calculus etc - Help check whether i did the question right in the exam!!!

[river thorn]

here's the question on my paper, spent a long time on it and was worth a lot of marks, want to make sure i got it right - mark scheme not out yet

[dawn pawn]

1. Ask your question and show the work you've done so far. If you've posted a screenshot of a question, specify which part you need help with.
2. Wait patiently for a helper to come along.
3. Once someone helps you, say thank you and close the thread with:

   +close
   

4. Feel free to nominate the person for helper of the week in #helper-nominations
5. Do not ping the mods, unless someone is breaking the rules.
6. If you're happy with the help you got here, and the server overall, you can contribute financially as well:

[river thorn]

this is GCSE further maths btw!!!

dont know how i'd figure this out using an online calculator

and theres no youtube videos on the paper yet

[robust eagle]

What's that Answer ........................................(3) ??

[river thorn]

thats the marks haha

[robust eagle]

And Answer ..............................................4(4)

LOL OK

[river thorn]

LMAOOO

[robust eagle]

DId you do in this qs in the exam?

[river thorn]

yep

two weeks ago

[robust eagle]

a = ?

[river thorn]

i got smth like 2.25 but idk if its right and i literally need like atleast 90% in this exam cus im cooked for mechanics

i need to know if i got it right

and i wouldlove a work through it

[robust eagle]

AHHH

I got a = 2/3 Lol

nah sry , a = 3/2

[river thorn]

wait that could be what i got

it was two weeks ago loll lemme check

[robust eagle]

Check it

[river thorn]

in the exam i put -2/3 for a 😥😥😥😥😥 losing hope

[robust eagle]

AHH NOO

it's 3/2

[river thorn]

can u do a lil diagram

cus idek how i got there in the exam i fr started pulling equations out my ass

[robust eagle]

Oh Ok , will do

actually now dinner time for me lol

I will come back

after sometime

[river thorn]

alrrr

STILL NEED HELP Algebra, calculus etc - Help check whether i did the question right in the exam!!!

[river thorn]

if anyone could like draw on this the answer step by step it would help me out immeasurably

[finite moss]

So we start from 9?

[river thorn]

Yuppp

[finite moss]

Are you familiar with derivatives

[river thorn]

I am

[finite moss]

Nice

So can you write the equation of the tangent through that point

[river thorn]

btw ive already done this question, this isnt like a "do my homework" type thing aha, jic, like i kinda wanna know if i got the answer right in the exam

[finite moss]

Ah

Tell me your process

[river thorn]

mark scheme isnt out yet

[river thorn]

ngl i dont quite remember, exam was on the 21st, i think i differentiated it then set it equal to y=3x+1?

i rememeber not beign able to get a from there so i did some absolutely random calculations in hopes of getting it

[finite moss]

You actually differentiate it and put x=-1

Then that's equal to the slope of y=3x+1

[river thorn]

Oh i remmeber doing that i just dk what step at 😭😭😭

[finite moss]

Which is ...?

[river thorn]

dk ngl

[finite moss]

So the slope is rise over run

Which in this case is 3

[finite moss]

So this is equal to 3

Now we can find the value of a

[river thorn]

let me write this down aha

of the tangent ye?

[finite moss]

The slope of the tangent is the value of the derivative at that point

We are given x=-1

The derivative of y=4+a/x^2 is....?

[river thorn]

-2a/x^3

[finite moss]

Good

Now put -1 in x

So 2a yeah?

[river thorn]

a = 3/2

[finite moss]

Yeah

[finite moss]

Now can you write the equation of the tangent through that point

[river thorn]

don't remember ngl,
though i know now i got the wrong answer in the exam haha,
Im not doing maths past this year

[finite moss]

Oh I am sorry to hear that

The equation of a line requires slope

And the point through which it's passing

[river thorn]

i put -2/3 there

omg why did i do reciprocal

Algebra, calculus etc - Help check whether i did the question right in the exam!!!

[tender shoal]

you just want the solution?

once you have a = 3/2, all you need is to find the point on the tangent. then use point slope form for equation of a line

[robust eagle]

Hi

[tender shoal]

normal is just perpendicular to the tangent, so the slope for c) is just -1/3

[robust eagle]

@river thorn I think you got your answer?

[robust eagle]

Thank you for joining dude

[latent thistle]

@robust eagle has given 1 rep to @glass nexus

[river thorn]

Hiyaaa sorry don’t have notifs on, thank you all ❤️❤️❤️

+close