The Student Room Group
no you're on the right lines :smile:
Yeah, flipping them and adding them together sounds like a good idea. That's the first thing I'd try, anyway :smile:
I think the method you are suggesting should work.

Spoiler

right so it then goes on to say:
The first three terms of an arithmetic series are k, 7.5 and k +7 respectively
B) Find the value of k

The wording has completely thrown me, probably really easy can anybody help?
Reply 6
d = difference between k and 7.5, as well as between 7.5 and k+7.
You should be able to equate two expressions to solve for k.
Reply 7
AveUgotaWkdSide
right so it then goes on to say:
The first three terms of an arithmetic series are k, 7.5 and k +7 respectively
B) Find the value of k

The wording has completely thrown me, probably really easy can anybody help?

It's saying that x1=k,x2=7.5,x3=k+7x_1 = k, x_2 = 7.5, x_3 = k+7, so:
[br]a=k[br]a+d=7.5[br]a+2d=k+7\newline[br]a = k\newline[br]a + d = 7.5\newline[br]a + 2d = k + 7

You can solve these simultaneously. I'll help you out by saying that you should replace aa by kk in the 2nd and 3rd equations.
Original post by electriic_ink

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Thank you, this is very useful because all the one's I see out there have too many terms for me to comfortably be able to recall the whole proof.

Spoiler

Reply 9
Original post by Wolfram Alpha
Thank you, this is very useful because all the one's I see out there have too many terms for me to comfortably be able to recall the whole proof.

Spoiler




Unapologetically necroing, lol.
Necroing is what?
@_gcx
Reply 11
Original post by Wolfram Alpha
Necroing is what?
@_gcx


Resurrecting something from the grave. I suppose it is Easter.