Question

1×3分之1+3×5分之1+5×7分之1+……+97×99分之1

Answer 1

1/(1*3)+1/(3*5)+1/(5*7)+...+1/(97*99)

=[(1/1-1/3)+(1/3-1/5)+(1/5-1/7)+...+(1/97-1/99)]*1/2

=(1-1/99)/2

=98/99*1/2

=49/99