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# Mega A Level Maths Thread MK II watch

1. Can someone help me on this C2 Binomial Expansion question, part B. How do I go about these questions? Thanks :-)

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2. (Original post by Westeros)

Can someone help me on this C2 Binomial Expansion question, part B. How do I go about these questions? Thanks :-)

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1 + x/4 = 1.025
x/4 = 0.025
x = 0.1

So sub that into your expansion
3. (Original post by Westeros)

Can someone help me on this C2 Binomial Expansion question, part B. How do I go about these questions? Thanks :-)

Posted from TSR Mobile
Break it up into two parts - (1 + 0.025)^8, and with the expansion you've just made, substitute x/4 with 0.025.

I think that's how you do it anyway. Forgive me if I'm wrong. xD

EDIT: OR, you can find the value of x by making x/4 = 0.025, and then substitute it into your expansion!
4. (Original post by L'Evil Fish)
1 + x/4 = 1.025
x/4 = 0.025
x = 0.1

So sub that into your expansion
Saviour
5. (Original post by Westeros)
Saviour
No problem!
6. (Original post by L'Evil Fish)
So, I want 95+ UMS in C3.

Any tips?

Also, question...

Parametric Functions, how to we find the second differential again?

Is it differentiating dy/dx wrt to t. And dividing by dt/dx?
OK, there are two ways:

- Firstly, you can convert to cartesian form and find the second derivative as you normally would.

- Secondly, you can find in terms of t, and differentiate this:

7. (Original post by DJMayes)
OK, there are two ways:

- Firstly, you can convert to cartesian form and find the second derivative as you normally would.

- Secondly, you can find in terms of t, and differentiate this:

So:

[(dy/dx) d/dt]/(dt/dx)
8. (Original post by L'Evil Fish)
So:

[(dy/dx) d/dt]/(dt/dx)
What you've written is confusing to read but yes, essentially you differentiate the function for dy/dx with respect to t and divide by dx/dt. I'd always chain rule it how I did though; as I think simply knowing how to do that is better than learning an algorithm for it.
9. (Original post by DJMayes)
What you've written is confusing to read but yes, essentially you differentiate the function for dy/dx with respect to t and divide by dx/dt. I'd always chain rule it how I did though; as I think simply knowing how to do that is better than learning an algorithm for it.
Yeah, that's how I do it... And how it was shown in the mark scheme

So I thought it the convention...
10. (Original post by L'Evil Fish)
Yeah, that's how I do it... And how it was shown in the mark scheme

So I thought it the convention...
Yes, but if you understand where it comes from you'll be in much better stead than someone who simply knows what you have to do, but doesn't understand why. An example I have for this is M1 vectors:

Take one of the reasonably frequent questions which tell you a vector is, for example, parallel to i. A lot of people will learn these questions as "If parallel to i, j components are 0" and vice-versa. This works, but it's not a good way of approaching said questions. If someone simply understands that two vectors are parallel if they are scalar multiples of each other, then they will be much better off, especially for questions which have it parallel to a less standard vector, like 5i - 14j, for example.

(Also, finally decided to take the plunge and get a profile picture.)
11. (Original post by DJMayes)
Yes, but if you understand where it comes from you'll be in much better stead than someone who simply knows what you have to do, but doesn't understand why. An example I have for this is M1 vectors:

Take one of the reasonably frequent questions which tell you a vector is, for example, parallel to i. A lot of people will learn these questions as "If parallel to i, j components are 0" and vice-versa. This works, but it's not a good way of approaching said questions. If someone simply understands that two vectors are parallel if they are scalar multiples of each other, then they will be much better off, especially for questions which have it parallel to a less standard vector, like 5i - 14j, for example.

(Also, finally decided to take the plunge and get a profile picture.)
So it's continuation of the chain rule?

Anyone know what M2 Vectors with Variable Acceleration is about? I've not covered M1 vectors because WJEC don't have them.
12. (Original post by L'Evil Fish)
So it's continuation of the chain rule?

Anyone know what M2 Vectors with Variable Acceleration is about? I've not covered M1 vectors because WJEC don't have them.
You can have your acceleration as a function of time. For example:

a is the rate of change of velocity with respect to time, so we can write:

and integrate to get

We can extend this idea to vectors:

a = 2ti+3t^2j

a is the derivative of v with respect to t, so we can integrate both sides with respect to t to get:

v = i +j
13. (Original post by DJMayes)
You can have your acceleration as a function of time. For example:

a is the rate of change of velocity with respect to time, so we can write:

and integrate to get

We can extend this idea to vectors:

a = 2ti+3t^2j

a is the derivative of v with respect to t, so we can integrate both sides with respect to t to get:

v = i +j
Okay... So that's it? Why use vectors at all? (excuse naivety)
14. (Original post by L'Evil Fish)
Okay... So that's it? Why use vectors at all? (excuse naivety)
For motion in multiple dimensions. if you don't use vectors you essentially have motion along a single line, which is unhelpful for a lot of physical situations. I believe you can get more dimensions by parametrics but vectors are easier/more effective for higher dimensions.
15. (Original post by DJMayes)
For motion in multiple dimensions. if you don't use vectors you essentially have motion along a single line, which is unhelpful for a lot of physical situations. I believe you can get more dimensions by parametrics but vectors are easier/more effective for higher dimensions.
Aah okay, but surely at M2 it won't be great anyway
16. Has anyone given any thought to the pi vs tau debate? The fact that 2pi crops up numerously in maths and physics and that it'd make more sense for tau (2pi) to be used.
17. Can anyone help me with 9(e)? I know you use logs but not sure how...

Thank you so much!

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18. (Original post by hello.cupcake)
Can anyone help me with 9(e)? I know you use logs but not sure how...

Thank you so much!

Posted from TSR Mobile
Just have substitute in r. Simplify a little. Tell me when you get stuck again!
19. (Original post by reubenkinara)
Has anyone given any thought to the pi vs tau debate? The fact that 2pi crops up numerously in maths and physics and that it'd make more sense for tau (2pi) to be used.
That debate is so exasperating. But this sums everything up quite well:
20. (Original post by PrinceyJ)
That debate is so exasperating. But this sums everything up quite well:
I've seen that and quite a few videos on the subject!

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