Question

Write the sum using sigma notation.
-3/8 + 4/7 - 5/6 + 6/5 - 7/4+ 8/3

Answer 1

Rob/Jeff -- please use the same name for your posts.

Answer 2

I assume you know how to write sigma: ∑

Note that the numerators go from 3 to 8, alternating signs, and the denominators count down from 8 to 3:

8
∑ (-1)^k * k/(11-k)
k=3