每一加法成分为:i*2i*3i/i*5i*10i 分子等于:6i^3求和,(i=1 to n)=6*(i*(i+1)/2)^2=[i(i+1)]^2*2/3=2(i^4+2i^3+i^2)/3 同理,分母等于50i^3求和,(i=1 to n)=50*(i*(i+1)/2)^2=2(i^4+2i^3+i^2)/25所以,原式等于根号下[2(i^4+2i^3+i^2)/3]/[2(i^4+2i^3+i^2)/25]=25/3等于5/3倍根号3。根号下81×82×83×84=根号下9*9*2*41*83*4*3*7=9*9*4*41*83*21=9*2*根号下41*83*21。