1)=13(13n?13n 1?...f(x(1)使f(x)0 x26x 61,它的解x1或5;因为d > 0,a11,a35,2d4,d2,∴an2n1(n∈N*)使n1×12 B1,其解b113..。
①当m点在AB线上,d点在q点为DQ⊥AB,BD相连,DM和CB延伸到p点相交,则AQBQ2,QMBM1,DQ23,在Rt△DQM,DM(23)2 PM133,∫BC∨ad。∴∠PMN120,∠ PBD 120,∴△PMN∽△PBD,∴PNPDPMPB,即43 BN13 13313343,解为bn3;②当m点在AB延长线上时,交点d是q点的DQ⊥AB,连接BD,然后是DQ23,BD4,DMDQ2 QM221,∫BP∨ad,∴MPPDBMAB14,BPADBMAB 15,∴BP45,∵ MP。∴△PBD∽△PMN,∴PMPBPNPD,也就是0)a31 2d,A514D3Q2,b5q^42d q^4201,4d q2122,1 *22,2q^4q2280 (2Q7) (q2>0
2、...Sn 2(n∈N*(I)可以从Sn 13Sn 2得到。当n > 1时,可通过减法得到Sn3Sn1 2,an 13an(3点)a12,∴数列{an}以2为第一项,以3为公比的几何级数∴ an = 2× 3n?1(6分)证明:(ii) Sn = 2 (3N?1)3?1=3n?一...(8分)所以BN = 2× 3N?1(3n?1)(3n 1?1)=13(13n?13n 1。
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2023-12-26 / 1.4.08
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