2/1x2+2/2x3+2/3x4+2/4x5+...+2/98x99+2/99x100
问题描述:
2/1x2+2/2x3+2/3x4+2/4x5+...+2/98x99+2/99x100
答
2/1x2+2/2x3+2/3x4+2/4x5+...+2/98x99+2/99x100
=2×(1-1/2+1/2-1/3+……+1/99-1/100)
=2×(1-1/100)
=2×99/100
=99/50