太难了,有简算吗?我有以下思路,但后面还是不行,能抛砖引玉吗?怀疑能否有简算.1) (4-3)/4 + (5-3)/5 + (6-3)/6 + ...+ (12-3)/12 = 9 - 3(1/4 + 1/5 +1/6 + ...+1/12)2) 题目抄错了?= 1*2*(4-1)/4 + 2*3*(5-1)/5 +.+ ...