令bn等于1/an2-1
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![令bn等于1/an2-1](/uploads/image/f/1792855-55-5.jpg?t=%E4%BB%A4bn%E7%AD%89%E4%BA%8E1%2Fan2-1)
Sn=(a1+an)n/2Sn=na1+n(n-1)d/2=n[2a1+(n-1)d]/2=na1+n²d/2-nd/2=n²d/2+n(a1-d/2)Sn=An²+Bn
1)bn都是正数,所以Tn》T1=b1=1/32)裂项bn=1/(n^2+2n)=1/(n(n+2))=[1/n-1/(n+2)]/2b1=(1-1/3)/2b2=(1/2-1/4)/2b3=(1/3
Sn=-an-(1/2)^(n-1)+2所以S(n-1)=-a(n-1)-(1/2)^(n-2)+2相减Sn-S(n-1)=an=-an-(1/2)^(n-1)+a(n-1)+(1/2)^(n-2)(
n=1,S1=a1=2,n>1,an=Sn-S(n-1)=2n,n=1时也适合,故:an=2nbn=(1/4)·1/n(n+1)4bn=1/n(n+1)=1/n-1/(n+1),所以:4Tn=[(1-
an+1=4-(4/an)a(n+1)-2=2-4/anb(n+1)=1/(a(n+1)-2)=1/(2-4/an)=an/(2an-4)=an/2(an-2)bn=1/(an-2)所以:b(n+1)
1美元=3.8令吉2004年4月30号的汇率如此算来1令吉=0.26315美元
n=1+1/n,Sn=b1+b2+b3+.+bnSn=1+1/1+1+1/2+1+1/3+.+1+1/nSn=n+1+1/2+1/3+.+1/n当n趋于无穷大时,上式可以近似用ln(n)+C来模拟亦即
上面的答案显然有点问题(1)an+2=(an+an+1)/22a(n+2)=an+a(n+1)2[a(n+2)-a(n+1)]=-[a(n+1)-an][a(n+2)-a(n+1)]/[a(n+1)-
令”是个数量单位,它是指“全张纸500张”,意思就是500张全张纸才是一令,那么1令=对开1000张=4开2000张=8开4000张=16开8000张.
∵在数列{an}中,a1=1,an+1=an2-1(n≥1),∴a2=a21-1=0,同理可得a3=-1,a4=0,a5=-1.∴a1+a2+a3+a4+a5=-1.故选:A.
证:a(n+1)=2an/(an+1)1/a(n+1)=(an+1)/(2an)=(1/2)(1/an)+1/21/a(n+1)-1=(1/2)(1/an)-1/2=(1/2)(1/an-1)[1/a
(1)由题,2a(n+1)-a(n)=n∴a2=3/4,a3=11/8,a4=25/16(2)证明:由2a(n+1)-a(n)=n∴a(n-1)=2a(n)-(n-1),(n≥2)∴b(n)/b(n-
an=4-(4/a的n-1项)(n大于等于2)令bn=1/an-2?
an-2=2-4/a(n-1)=[2a(n-1)-4]/a(n-1)1/(an-2)=a(n-1)/[2a(n-1)-4]=[a(n-1)-2+2]/2[a(n-1)-2]=1/2+1/[a(n-1)
1.证:a(n+1)=an²+4an+2a(n+1)+2=an²+4an+4=(an+2)²log3[a(n+1)+2]=log3[(an+2)²]=2log3
(n+1)=a(n+1)+1=[2an+1]+1=2an+2=2(an+1)=2bn,所以{bn}是公比为2的等比数列.b1=a1+1=2,所以bn=b1*q^(n-1)=2*2^(n-1)=2^n.
Sn+an=nS(n-1)+a(n-1)=n-1an+an-a(n-1)=12an=a(n-1)+1bn=an-12an-2=a(n-1)-12bn=b(n-1)bn=(1/2)b(n-1)故等比a1
∵当n=2时,a1+a2=3,当n=1时,a1=1,∴a2=2,∴公比q=2,∴等比数列{an}是首项是1,公比是2的等比数列,∵a12=1,a22=4,∴等比数列{an2}是首项是1,公比是4的等比
a(n+2)=[an十a(n+1)]/2=a(n+2)-a(n+1)=[an-a(n+1)]/2化b(n+1)=-1/2*bn(因bn=a(n+1)-an){bn}等比数列,b1=1,公比-1/2则b