1/4×5+1/5×6+1/6×7+1/7×8=
问题描述:
1/4×5+1/5×6+1/6×7+1/7×8=
答
1/4×5+1/5×6+1/6×7+1/7×8
=1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8
=1/4-1/8
=1/8