Question

1乘2乘3分之1加2乘3乘4分之一加3乘4乘5分之一,一直加到48乘49乘50分之一

Answer 1

=(1/2)×(1/1×2+1/2×3)+(1/2)×(1/2×3-1/3×4)+……+(1/2)×(1/48×49-1/49×50)

=(1/2)×(1/1×2+1/2×3+1/2×3-1/3×4+……+1/48×49-1/49×50)

=(1/2)×(1/1×2-1/49×50)

=306/1225