Shout here for any general help on Pure Maths stuff from Y12 or Y13…
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Pure Maths123 comments to Pure Maths |
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Copyright © 2012 The Sydenham High School Mathematics Department Blog - All Rights Reserved |
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Pure MathsShout here for any general help on Pure Maths stuff from Y12 or Y13… 123 comments to Pure Maths |
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Copyright © 2012 The Sydenham High School Mathematics Department Blog - All Rights Reserved |
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Hi Becky,
Just realised my reply to you hasn’t appeared. Sorry.
Yes n=8.
d=200 because her allowance increases by 200 each year.
Completing the square:
eg x^2 + 6x + 2
becomes (x+3)^2 -9 +2
= (x + 3)^2 – 7
comparing this with the general format they give you, the ‘a’ is the 3 and the b is -7
Does that help?
JT
oh yes got it for the completing the square!! I see. So I got U8=1900…is that right??
Yes, that’s right
(Mr W and I attacked the custard creams today – wonderful xxx)
YEY!!! okay so that means ive done them all apart from question 7d but that looks like a long question so I might speak to you tomorrow about it. Ah good, glad you enjoyed them..you deserved them!
xx
For 7d put your sum to n terms = 32000
n will be your only unknown
It turns into a quadratic with big numbers but you can divide them down into something smaller. Quadratic factorises. Use the answer that makes sense and you’ll be there
aah i did that just got a bit stuck because I wasn’t sure what L is?? is it still 1900?
No because you don’t know what n is so you have to leave it in terms of n.
The nth term is the last term so it’s a+(n-1)d
With numbers, that becomes 500+200(n-1)
Makes a nice mess for you to tidy up
Good luck!
You could just work it out year on year keeping a running total till you reach 32000.
Thank you Mrs Tibble….I did that and got to 318.5 in the end which doesn’t sound right so I will talk to you tomorrow. See you tomorrow
Aaaaah Miss, I am so confused!! I am completely stuck on question 13 and 18 of ex 6H from Mr Williams Homework. I don’t even know where to start!! Please help me
Becky, for 13a) Use the formula Un=a+(n-1)d
where a is 50, d=50 and n=10, because as n goes up by 1, the sequence increases by 50
(if that makes sense?)
then for 13b) use the formula Sn=1/2n[2a+(n-1)d], where you know Sn is 76 000 and you know a and d, so you are finding n
Thanks Vish,
I will have another go and let you know how i got on
Thank you
Hi guys,
Are you sorted now? Thanks for helping each other: I was in school (6th form choices evening)
Vishali – did you leave your C1 in my room?
JT
no im still confuzzledddd
I am finding this so hard! on Que 13 a) ive done the un=a=d(n-1) and got to u10=500…now what do i do to prove that makes 500m is 11 300?? Hope you had a good evening with lots of people thinking of taking maths for A-Level!! 
I probably did, can’t find it, so using my own copy to do my hw
are you free period 1 tomorrow?? Im going to go to bed soon and will just explain to Mr Williams i found it really difficult
Hi Becky,
Start writing out the terms of the sequence (and number them)
1st is £500 (50m)
2nd is £640 (100m)
3rd is £780 (150m)
4th is £920 (200m)
5th is £1060 (250m)
nth is 500 + 140(n-1) (nx50 metres)
Following the depth pattern means 500m will be the 10th term
Thank you Mrs Tibble, I will go and see Mr Williams tomorrow morning to go through it.
thank you for you help! 
We’ve got 10, 11, 9 in the morning. I’ve got 13s period 4 so Mr W might be free then – unless he’s got you!
Mrs T
Hi Mrs Tibble,
Did we have any homework that was in for this term? I wrote in my journal ‘finish exercise’ but i have no idea which exercise because it has been so long. oops!
Hi Becky,
I don’t think that was C1; could have been stats.
No idea
Mrs T
Ah okay thank you. I might ask the others tomorrow because ive got no idea what that was. I had a look in my folder and couldn’t find anything. Hmmmm…very strange