数学1尀2+5尀6+11尀12+9尀20+......9890尀9900怎么做

2024-12-14 22:51:38
推荐回答(2个)
回答1:

1\2+5\6+11\12+9\20+......9890\9900
=(1-1/2)+(1-1/6)+(1-1/12)+......(1-1/9900)
=[1-1/(1×2)]+[1-1/(2×3)]+[1-1/(4×3)]......[1-1/(99×100)]
=99-[1/(1×2)+1/(2×3)+1/(4×3)+......1/(99×100)]
=99-[(1-1/2)+(1/2-1/3)+(1/3-1/4)+......(1/99-1/100)]
约去得
99-(1-1/100)
98.01

回答2:

奖励