Edexcel C2 20th May 2015 *Official Thread*

It's really up to you. Generally we use n-1 because we start with a, and the 2nd term has ar, third term ar^2.
Sometimes with years (often if it starts in year 2000) it's easier to start on year 0 (and use ar), even if it's more confusing. If you're not sure, stick with ar^(n-1)

Why is it easier to use ar^n for years?


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I only have four students on this paper tomorrow and they are all strong.

Therefore, I hope the paper is disgusting!

Where's the sector on your drawing? But confused.

i defo will be

Could someone please explain what they did here?

sector is the semicircle. it's a sector of angle Pi radians. A half circle.

Because sometimes if we start in year 2000, it's easier to call that year 0 than year 1. Really it's just people who are more confident saving time. There's no real benefit of it, it's just being fancy.

Does anyone know if we can use the sum for geometric series for for when common ration is more than one

Does anyone know if we can use the sum for geometric series for for when common ration is more than one

Does anyone know if we can use the sum for geometric series for for when common ration is more than one

yeah you just 1-r, and swap them so its r-1. when r>1

yeah you just 1-r, and swap them so its r-1. when r>1

yeah you just 1-r, and swap them so its r-1. when r>1

why wouldn't it work if you do it the original way?

It still works, it just gives you a negative value. Our teacher taught it to us, that if r>1 than we had to swap it and do r-1.

do you want to help eachother seeing as we'll both still be up? I know it won't go bad but still scared

hm okay
Idk man hopefully should be an alright paper