(1)2,1,4,3,8,5,( ) A.8 B.10 C.12 D.13(2)1,0.5,1,4,( ),216 A.25 B.27 C.32 D.36

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(1)2,1,4,3,8,5,( ) A.8 B.10 C.12 D.13(2)1,0.5,1,4,( ),216 A.25 B.27 C.32 D.36

(1)2,1,4,3,8,5,( ) A.8 B.10 C.12 D.13(2)1,0.5,1,4,( ),216 A.25 B.27 C.32 D.36
(1)2,1,4,3,8,5,( ) A.8 B.10 C.12 D.13
(2)1,0.5,1,4,( ),216 A.25 B.27 C.32 D.36

(1)2,1,4,3,8,5,( ) A.8 B.10 C.12 D.13(2)1,0.5,1,4,( ),216 A.25 B.27 C.32 D.36
(1)2,1,4,3,8,5,( )
a1=2
a3=a2+a4,a4=a1+a2,a3=2a2+a1=2a1
a5=a4+a6,a6=a2+a3,a5=a2+a3+a4=a3+2a2+a1=4a2+2a1=2(2a2+a1)=4a1
a7=a6+a8,a8=a3+a4,a7=a3+a4+a6=2a3+2a2+a1=6a2+3a1=3(2a2+a1)=6a1
所以奇数项为:
a1=2
a(2n-1)=2(n-1)a1
a7=2(3a1)=12
(2)1, 0.5, 1, 4, ( ), 216
1^k, 2^(-1), 3^0, 4^1, (5^x), 6^3
指数为k,-1,0.1,x,3
x=2
5^x=5^2=25