等差数列{an},{bn}的前n项和分别为Sn,Tn,Sn/Tn=2n/3n+1则a3/b5
等差数列{an},{bn}的前n项和分别为Sn,Tn,Sn/Tn=2n/3n+1则a3/b5
是a3/b5不是其他
是a3/b5不是其他
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2n/3n+1?
2n/(3n+1)?
2n/(3n+1):,n=1,a1/b1=1/2,b1=2a1
a2=a1+d,b2=b1+c=2a1+c,a2/b2=4/7=(a1+d)/(2a1+c),8a1+4c=7a1+7d,a1=7d-4c
a3=a1+2d,b3=b1+2c=2a1+2c,a3/b3=3/5=(a1+2d)/(2a1+2c),6a1+6c=5a1+10d,a1=10d-6c=7d-4c
3d=2c,c=3d/2,a1=7d-6d=d,b1=2d
a3=a1+2d=3d,b5=b1+4c=2d+6d=8d
a3/b5=3/8
2n/(3n+1)?
2n/(3n+1):,n=1,a1/b1=1/2,b1=2a1
a2=a1+d,b2=b1+c=2a1+c,a2/b2=4/7=(a1+d)/(2a1+c),8a1+4c=7a1+7d,a1=7d-4c
a3=a1+2d,b3=b1+2c=2a1+2c,a3/b3=3/5=(a1+2d)/(2a1+2c),6a1+6c=5a1+10d,a1=10d-6c=7d-4c
3d=2c,c=3d/2,a1=7d-6d=d,b1=2d
a3=a1+2d=3d,b5=b1+4c=2d+6d=8d
a3/b5=3/8
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