x(2/1*3+2/3*5+2/5*7+……+2/2003*2005)=2004
x(1-1/3+1/3-1/5+1/5-1/7+……+1/2003-1/2005)=2004
x(1-1/2005)=2004
x*2004/2005=2004
x==2005