已知数列{log2（an-1）}（n∈N*）为等差数列，且a1=3，a2=5，则
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数列{log2（an-1）}（n∈N*）为等差数列，
设其公差为d，则log2（an-1）-log2（an-1-1）=d，
即
=2d，又由a1=3，a2=5，an-1 an-1-1
则d=1，即
=2，an-1 an-1-1
{an-1}是以a1-1=2为首项，公比为2的等比数列，
进而可得，an-1=2n，则an=2n+1，
故an-an-1=2n-2n-1=2n-1，
则
（lim n→∞
+1 a2-a1
+…+1 a3-a2
）=1 an+1-an
（lim n→∞
+1 2
+…+1 4
）=1，1 2n-1
故选C．
| 阅读理解。 | ||
| You are travelling in Inner Mongolia. You want to book a room in a hotel, but you don't know any hotels. Look at the following two pages from a brochure (小册子). Then answer the questions.
______________________________ 2. How much will you pay if you want a double room for two days at the Grassland Hotel? ______________________________ 3. How long are the restaurants at Happy Holiday Hotel open for? ______________________________ 4. Where should you stay if you want to ride a horse? ______________________________ 5. Why are the double rooms more expensive at the Grassland Hotel? ______________________________ | ||