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AMC数学竞赛真题2016年B 3-4

2018-11-16 重点归纳

AMC10数学竞赛是美国高中数学竞赛中的一项,是针对高中一年级及初中三年级学生的数学测试,该竞赛开始于2000年,分A赛和B赛,于每年的2月初和2月中举行,学生可任选参加一项即可。不管是对高校申请还是今后在数学领域的发展都极其有利!那么接下来跟随小编来看一下AMC10数学竞赛真题以及官方解答吧:

Problem 3

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

$\textbf{(A)}\ -2016\qquad\textbf{(B)}\ 0\qquad\textbf{(C)}\ 2016\qquad\textbf{(D)}\ 4032\qquad\textbf{(E)}\ 6048$

Solution

Substituting carefully, $\Bigg\vert\Big\vert 2016-(-2016)\Big\vert-2016\Bigg\vert-(-2016)$

becomes $|4032-2016|+2016=2016+2016=4032$ which is $\boxed{\textbf{(D)}}$.

Solution 2

Solution by e_power_pi_times_i

Substitute $-y = x = -2016$ into the equation. Now, it is 美国数学竞赛AMC有用吗. Since $y = 2016$, it is a positive number, so $|y| = y$. Now the equation is $\Bigg\vert\Big\vert y+y\Big\vert-y\Bigg\vert+y$. This further simplifies to $2y-y+y = 2y$, so the answer is $\boxed{\textbf{(D)}\ 4032}$

Problem 4

Zoey read $15$ books, one at a time. The first book took her $1$ day to read, the second book took her $2$ days to read, the third book took her $3$ days to read, and so on, with each book taking her $1$ more day to read than the previous book. Zoey finished the first book on a Monday, and the second on a Wednesday. On what day the week did she finish her $15$th book?

AMC数学竞赛报考点

Solution

The process took $1+2+3+\ldots+13+14+15=120$ days, so the last day was $119$ days after the first day. Since $119$ is divisible by $7$, both must have been the same day of the week, so the answer is $\textbf{(B)}\ \text{Monday}$

以上就是小编对AMC10数学竞赛真题以及解析的介绍,希望对你有所帮助,如果想了解更多关于AMC数学竞赛报考点、AMC美国大学生数学竞赛、美国数学竞赛AMC有用吗以及AMC学习资料等信息请持续关注AMC数学竞赛网