2006 AMC 10B Problem 1

Below is the professionally curated solution for Problem 1 of the 2006 AMC 10B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2006 AMC 10B solutions, or check the answer key.

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Concepts:exponentpairing and grouping

Difficulty rating: 720

1.

What is (1)1+(1)2++(1)2006?(-1)^1 + (-1)^2 + \cdots + (-1)^{2006}?

2006-2006

1-1

00

11

20062006

Solution:

There are 20062006 terms. Pairing consecutive terms gives (1+1)+(1+1)+.(-1+1)+(-1+1)+\cdots. Since 20062006 is even, every term pairs off and the sum is 0.0.

Thus, the correct answer is C.

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