1. The problem statement, all variables and given/known data Here's my question. My school recently taught me finding summation using method of difference and what my teacher taught was just involving 2 partial fractions. But this question appeared in my exercise given by my teacher. r th term: (2r-1)/r(r+1)(r+2). Find summation of n th terms begin with r=1. Can someone show me how to solve this using method of difference? 2. The attempt at a solution What I got is sum (- 1/2r + 3/r+1 - 5/2(r+2) ). And I stucked. What I used to know is r th term is f(r) - f(r-1). and sum of rth term is f(n)- f(0). I cant get the f(r) - f(r-1) either because -1/2r and -5/2(r+2) both having the same sign.