1. The problem statement, all variables and given/known data U( r ) = r(r+1)(r+2)(r+3), show that U (r + 1) - U ( r ) = 4(r+1)(r+2)(r+3) Hence, find the sum to n terms of the series 2x3x4 + 3x4x5 + 4x5x6 +..... 2. Relevant equations Sequence Knowledge.. 3. The attempt at a solution I can't even TOUCH on the problem. Can you please help?