https://www.khanacademy.org/math/class-10-algebra-od/xdf6c731a6bbb91d2:arithmetic-progressions/xdf6c731a6bbb91d2:difference-formula/v/difference-formula 2026-07-16T04:20:50.611819751Z Difference Formula In this video, you’ll master the Difference Formula (Method of Differences) to easily find the sum of complex sequences and series. We begin with a clear introduction to how telescoping terms cancel out, before diving into step-by-step derivations for the sum of squares ($\sum n^2$) and the sum of cubes ($\sum n^3$) of the first $n$ natural numbers. You'll also get a solid breakdown of Sigma notation to confidently read and write summations, concluding with a practical, hands-on example solving the consecutive product series 1.2 + 2.3 + 3.4 + ... + n(n+1). Khan Academy video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Difference Formula In this video, you’ll master the Difference Formula (Method of Differences) to easily find the sum of complex sequences and series. We begin with a clear introduction to how telescoping terms cancel out, before diving into step-by-step derivations for the sum of squares ($\sum n^2$) and the sum of cubes ($\sum n^3$) of the first $n$ natural numbers. You'll also get a solid breakdown of Sigma notation to confidently read and write summations, concluding with a practical, hands-on example solving the consecutive product series 1.2 + 2.3 + 3.4 + ... + n(n+1). https://cdn.kastatic.org/ka-youtube-converted/o02VzmlDlWY.mp4/o02VzmlDlWY.mp4 854 Difference Formula