x [1/3 + 1/15 +1/35 +...+ 1/(2005*2007)]=1x*[1/2(1-1/3) + 1/2(1/3-1/5) +1/2(1/5-1/7) +...+1/2(1/2005-1/2007)]=1(x/2)*(1-1/3+1/3-1/5+1/5-1/7+...+1/2005-1/2007)=1(x/2)*(1-1/2007)=1x=2007*2/2006x=2007/10...