Question

1/3*5+1/5*8+1/8*11+.+1/98*101

Answer 1

题目应该是

1/2*5+1/5*8+1/8*11+...+1/98*101

吧

1/2*5=(1/2-1/5)/3

1/5*8=(1/5-1/8)/3

1/8*11=(1/8-1/11)/3

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.

.

1/98*101=(1/98-1/101)/3

把上式累加得到

1/2*5+1/5*8+1/8*11+...+1/98*101

=(1/2-1/101)/3

=33/202