Question

计算：l1-1/2l+l1/2-1/3l+1/3-1/4l+……+l1/9-1/10l

Answer 1

|1-1/2|+|1/2-1/3|+|1/3-1/4|+……+|1/9-1/10|

=(1-1/2)+(1/2-1/3)+(1/3-1/4)+.+(1/9-1/10)

=1-1/2+1/2-1/3+1/3-1/4+.+1/9-1/10

=1-1/10

=9/10