Comments on: Mr Brewin’s Y12 – C1 – Sequences

By: Mr Brewin

Mr Brewin — Wed, 07 Jan 2009 22:02:31 +0000

It’s right there in the text book. You start with a + (a + d) + (a + 2d)… up to (a + (n-1)d) then you reverse it, and subtract… Enough to go on?

By: Bernice

Bernice — Wed, 07 Jan 2009 21:27:41 +0000

how do you prove that Sn=1/2n (2a+(n-1)d) using gauss’ method????

By: Mariam

Mariam — Tue, 30 Dec 2008 19:46:15 +0000

for the january stats exam, we only have to revise up to 5.3 rite, the addition rule???

By: Mariam

Mariam — Mon, 29 Dec 2008 19:10:26 +0000

oh rite, i think i get it now, thanks sir

By: Mr Brewin

Mr Brewin — Mon, 29 Dec 2008 18:49:49 +0000

Ooops… Latex not working in comments.

(k – 33 1/3) ( k + 35)

By: Mr Brewin

Mr Brewin — Mon, 29 Dec 2008 18:49:05 +0000

OK… So it looks like that’ll go to:

$latex (x – 33\frac{1}{3})(x +35) \latex$

Thanks to http://www.math.com/students/calculators/source/quadratic.htm

By: Mariam

Mariam — Mon, 29 Dec 2008 15:25:35 +0000

Ive got the equation 3k^2+5k-3500<0
its from the paper- 10 January 2007- afternoon
reference :6663/01
I hope thats helpful, and thanks for helping

By: Mrs Tibble

Mrs Tibble — Sat, 27 Dec 2008 18:00:02 +0000

Hi Mariam,
There must be some info somewhere in the question which will enable you to turn this expression into an equation. You can’t solve for k without an equation.
If you can’t find it, you’ll need to give me the paper details or type out the question.
Have fun,
Mrs T

By: Mariam

Mariam — Sat, 27 Dec 2008 15:04:57 +0000

in one of the past papers part of a question is: show that k satisfies (3k-100)(k+35), which i’ve done, but i can’t seem to get the next bit- find the value of k.
The answer says its 100/3 so k=33 but i dont know where these numbers have come from…. help please

By: Mrs Tibble

Mrs Tibble — Wed, 19 Nov 2008 18:39:48 +0000

Hi Deola,

No, you can differentate more than once. The first derivative gives you the gradient ie how the function is changing with x. The second derivative tells you how the gradient is changing with x, and thus it is used to work out whether a turning point is a max or min.

Mrs T