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    Ok, so we just started arithmetic series today in class, which seems pretty easy so far. He gave us questions 1-4 to complete for tomorrow, which I've done, so I thought I'd just go on and do questions 5-10 as well because I have a terribly sad life with nothing better to do I managed to do questions 5-9, it's just that 10 seems to be a wee bit different. Any pointers on it would be appreciated

    A sum to n terms of a series is given by kn^2 + n where k is a constant. Show that the series is arithmetic.
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    Find a_1 + a_2 + \cdots + a_n and a_1 + a_2 + \cdots + a_{n-1}. What might you do with these to isolate a_n? Once you know the nth term of the sequence you know the nature of the series.
 
 
 
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