1.1\2-[-(+1\6)-(+1\12)]+[-(-1\20)+1\30]-[(-1\42)+1\56]本人只知道这么写：=1_数学解答

1.1\2-[-(+1\6)-(+1\12)]+[-(-1\20)+1\30]-[(-1\42)+1\56]
本人只知道这么写：
=1×1\2+1\2×1\3+1\3×1\4+1\4×1\5+1\5×1\6-1\7×1\8
2.在1、2、3、……、50前添加“+”或“-”,并求它们的和,所得结果的最小非负数是多少?请列式解答.

人气：274 ℃　时间：2020-06-15 11:29:23

解答

1.原式=1×1\2+1\2×1\3+1\3×1\4+1\4×1\5+1\5×1\6-1\7×1\8 =1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7-1/7+1/8=1/2+1/2-1/7-1/7+1/8=1-2/7+1/8=5/7+1/8=47/56=7/82.-1+2+（3-...