An algebra problem by Prakhar Singh
If the sum of the terms of an arithmetic progression is , find the term of this progression.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
1 solution
S {n} = an^{2} + bn S {n-1} = a( n-1)^{2} + b (n-1) t {n} = S {n} - S_{n-1} = an^{2} + bn -a (n-1)^{2} - b (n-1) = an^{2} - an^{2} + 2an - a + bn - bn + b = 2an - a + b