原式=[(1997-2)*(1997+2)]*[(1997+1)*(1997-1)]*1997 =(1997^2-4)*(1997^2-1)*1997 =(1997^4-5*1997^2+4)*1997 =(2000-3)^5-(2000-3)^3*5+4*1997 然后用二项式定理可求解