(7²+1)/(7²-1)+（9²+1）/（9²-1）+…+（99²+1）/（99²-1）简便运算 急

(7²+1)/(7²-1)+（9²+1）/（9²-1）+…+（99²+1）/（99²-1）简便运算 急
(7²+1)/(7²-1)+（9²+1）/（9²-1）+…+（99²+1）/（99²-1）简便运算 急

(7²+1)/(7²-1)+（9²+1）/（9²-1）+…+（99²+1）/（99²-1）简便运算 急

(7²+1)/(7²-1)+（9²+1）/（9²-1）+…+（99²+1）/（99²-1）
=[1+2/(7²-1)]+[1+2/(9²-1)]+[1+2/(11²-1)]+……+[1+2/(99²-1)]
=1+2/(7+1)(7-1)+1+2/(9+1)(9-1)+1+2/(11+1)(11-1)+……+1+2/(99+1)(99-1)
=1×47+2/6*8+2/8*10+2/10*12+……+2/98*100 （有47个1相加）
=47+（1/6-1/8+1/8-1/10+……+1/98-1/100）
=47+1/6-1/100
=47+94/600
=47又47/300 （47又300分之47）