x/3+x/15+x/35+ +x/2011*2013=2012
x(1/1×3+1/3×5+1/5×7+.+1/2011×2013)=2012
x/2(1/1-1/3+1/3-1/5+1/5-1/7+.+1/2011-1/2013)=2012
x(1-1/2013)=2×2012
x(2012/2013)=2×2012
x=4026