2016 AMC 10B Problem 3

Below is the professionally curated solution for Problem 3 of the 2016 AMC 10B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2016 AMC 10B solutions, or check the answer key.

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Concepts:absolute value

Difficulty rating: 960

3.

Let x=2016.x=-2016. What is the value of xxxx?\Bigg\vert\Big\vert |x|-x\Big\vert-|x|\Bigg\vert-x?

 2016 \ -2016

 0 \ 0

 2016 \ 2016

 4032 \ 4032

 6048 \ 6048

Solution:

Observe that: xxxx=xxxx=2xxx\begin{align*} &\Bigg\vert\Big\vert |x|-x\Big\vert-|x|\Bigg\vert-x\\ &=\Bigg\vert \Big\vert -x-x\Big\vert-|x|\Bigg\vert-x \\ &=\Bigg\vert\Big\vert -2x\Big\vert-|x|\Bigg\vert-x \end{align*} since x<0x < 0 implies that x=x.-x = |x|. Substituting values, we can see that 40322016(2016)|4032-2016|-(-2016) =2016+2016= 2016 +2016 =4032.= 4032.

Thus, the correct answer is D .

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