Question

Find the sum

(-1)^1 + (-1)^2 + (-1)^3 +.......+(-1)^50

Answer 1

well look at the pattern of the simplified terms

-1 + 1 - 1 + 1 - 1 + 1 ......

and 50 is an even number... so what do you notice about the sum of each pair...?

Answer 2

-1

Answer 3

so looking at the 1st 2 terms

-1 + 1 =

if there are 50 terms then there are 25 pairs...

so sum the 1st 2 terms and then multiply by 25...

and please don't guess