gaokao 2017 Q12

gaokao · China · national-I-science 5 marks Geometric Sequences and Series Find a Threshold Index (Algorithm or Calculation)

The answer to a problem is: The sequence is $1, 1, 2, 2^0, 2^1$, and the next three terms are $2^0, 2^1, 2^2$, and so on. The first term is $2^0$. Find the smallest positive integer $N$ such that $N > 100$ and the sum of the first $N$ terms of this sequence is an integer power of 2.
A. 440
B. 330
C. 220
D. 110

The answer to a problem is: The sequence is $1, 1, 2, 2^0, 2^1$, and the next three terms are $2^0, 2^1, 2^2$, and so on. The first term is $2^0$. Find the smallest positive integer $N$ such that $N > 100$ and the sum of the first $N$ terms of this sequence is an integer power of 2.

A. 440

B. 330

C. 220

D. 110

Paper Questions

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