Could anyone help with this Maths GCSE question please??

[E1nste1n]

Thankyou - exam tomorrow!

@noblegiraffe ?
I have disappointingly forgotten how to do this over the past 35 years.
it wasn't on DD1's GCSE syllabus.

Or OP repost in Secondary.

If you differentiate this you get 2x^2 - 27.

A turning point would be when this = 0 so re arranging would give x to be 3 and -3.

Put these x values into the equation to give values of y then subtract them.

Hope this helps.

sd249

Now I know where I was going wrong. I read it as x2 not x3 whereas obviously it had to be x^3 due to the two turning points.

But when you differentiate you get 3x^2-27 =0 to give the correctly stated +3 or -3

In principle, the 1st derivative when equal to zero will give you the values of x at those points on the graph. Use those two values of x to give you a pair of simultaneous equations to solve for k.
Once you have the full form of the original equation, sub your x values to get y and hence solve the difference between b and d.

Oh yeah - typo sorry!

You don't need to find k as you are subtracting the two y values

I have to say this means nothing to me, but will show DS!

Thankyou

Also..,,,

????

True, k comes out in the wash.

@bungaloid don't need to solve for k -when you do b-d the ks cancel

When you differentiate, you are finding the gradient of the tangent to the curve at any place on the curve.
At a turning point the tangent is horizontal and so has zero gradient.

Explaining differentiation isn't something I'd like to try any further over a MN thread.

sqrt(a) = a^1/2

So you have a1.5 / a-2 = a(1.5--2) = a3.5

k=3.5

I can't read the other one.

(Sorry for the diff explanation, your picture didn't come up first time round)

OK. I think it says 2n - 1 / 4n - 1

4n - 1 = 22n -1 = (2n - 1)(2n + 1)

So divide top and bottom by 2^n -1 and you end up with

1 / 2^n +1

These are quite hard. I assume your DS is hoping for a 7+ ?

Thankyou for this.

It’s been some years since I did Maths GCSE.

This is the EdExcel IGCSE - first paper!

You can get up to a 9 with it, but there’s also “Further Maths” paper.

All the papers should be equally hard, i.e. they shouldn't get harder.
The later questions in the paper are for the higher grades.
These look to me like questions which would be quite late on.
What is your DS hoping for?

Wow. I got an A in maths and this I dont remember this...

He’s hoping for 8 in maths. Last year in his school, over 50% got a 9, but he doesn’t think he’ll be in that half.

@kneel they updates the sylbabbus a year or so ago. I did mine 7 years ago and some of this stuff wasn't on until a level

I don't mean to be goady, but are these considered hard questions under the British school curriculum?

silver

Yes these are considered hard.
In a paper aimed at GCSE level.

GCSEs are taken at 15/16. The British system does not hold children back. These questions will be for the top 7-9 grades only.
The knowledge they require is of no use in everyday life and only helpful if they study maths/science/economics further.

NB This isn't really 'British' this is England & Wales.

Why silvercuckoo? what country's curriculum would these be considered really easy?

@TeenTimesTwo
Thanks, I was genuinely interested. I am familiar only with my own country of origin maths curriculum, so was surprised when someone mentioned upthread that it is for an advanced secondary exam, seemed just a little bit too simple.
Just reinforces my decision to escape when my children are approaching secondary school age :)