2×1/1+2×3/1+3×4/1+4×5/1+……49×50/1怎么解?

问题描述:

2×1/1+2×3/1+3×4/1+4×5/1+……49×50/1怎么解?

2×1/1+2×3/1+3×4/1+4×5/1+……49×50/1
=(1/1-2/1)+(2/1-3/1)+……+(49/1-50/1)
=1-50/1
=50/49