gwd 11-Q25

[u9069700]

Q25:
If the sequence x1, x2, x3, …, xn, … is such that x1 = 3 and xn+1 = 2xn – 1 for n ≥ 1, then x20 – x19 =

A. 2^19
B. 2^20
C. 2^21
D. 2^20 - 1
E. 2^21 - 1

Answer:A

算了很久..還是得不出這麼簡潔的答案耶...
請問正確的解法?

[homaru]

http://www.formosamba.com/phpBB3/viewtopi ... B1+%3D+2xn
這邊:)

[u9069700]

謝謝您~~~~