(1+1/11+1/13+1/17)x(1/11+1/13+1/17+1/19)-(1+1/11+1/13+1/17+1/19)x(1/11+1/13+1/17)=(1+1/11+1/13+1/17)x(1/11+1/13+1/17+1/19-1/11-1/13-1/17)=(1+1/11+1/13+1/17)x1/19=2972/46189
19／1
