x/1×3+x/3×5+x/5×7+.+x/2007×2009=2008
x/2×(2/1×3+2/3×5+2/5×7+.+2/2007×2009)=2008
x/2×(1/1-1/3+1/3-1/5+1/5-1/7+.+1/2007-1/2009)=2008
x/2×(1-1/2009)=2008
x/2×2008/2009=2008
x=2×2009
x=4018