I´m trying to learn something about matematical induction. This chapter starts with sums (Sigma)
There is this easy problem I do not understand.
It says calculate the Sigma: from k=1;to n. where
The textbook answer says: Answer:
But when I do it I get:
starts at k=1 so I get:
Now I try to evaluate the last term:
/multiply by n(n+1)
that gives me
so I get
Now to evaluate the sum I take the (first term +last term)multiply by n and devide by 2.
That gives me =
clearly Iám doing someting very very stupid...anyone got an idéa whats wrong here?