Q2 ii). June 2006, 4722 C2 A/S level maths

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A sequence of terms u1, u2, u3, . . . is defined by u1 = 2 and un+1= 1 − un for n ≥ 1. Answers to part i) u1= 2, u2= -1, u3 = 2, u4= -1 (ii) Find 100 ∑ n=1 un

The answer to part ii) is 50 but I don't understand how it's that answer, I don't understand the mark scheme at all! ;( 

Sorry if this isn't clear enough but I couldn't copy an image on here. I'm so stuck and my exam is tomorrow. I would really appreciate any help :) **

Posted Thu 17th May, 2012 @ 17:52 by Rose
Edited by Rose on Thu 17th May, 2012 @ 17:54

1 Answer

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The sequence is arrathmetic and the funny sign (can't copy it) basically means, find the sum of the first 100 numbers so you should just use the formula out of the book! Sorry this is late but i'm guessing you had your C2 on friday, in which case a question like this didn't come up anyway!! Hope the exam went well for you, I found it horrible!! 

Answered Sat 19th May, 2012 @ 23:59 by Oliver