AMC10 2016 B
AMC10 2016 B · Q1
AMC10 2016 B · Q1. It mainly tests Exponents & radicals.
What is the value of $\dfrac{2a^{-1}+\dfrac{a^{-1}}{2}}{a}$ when $a=\dfrac{1}{2}$?
当 $a=\dfrac{1}{2}$ 时，$\dfrac{2a^{-1}+\dfrac{a^{-1}}{2}}{a}$ 的值是多少？
(A)
1
1
(B)
2
2
(C)
$\frac{5}{2}$
$\frac{5}{2}$
(D)
10
10
(E)
20
20
Answer
Correct choice: (D)
正确答案：（D）
Solution
Answer (D):
$\dfrac{2\left(\dfrac{1}{2}\right)^{-1}+\dfrac{\left(\dfrac{1}{2}\right)^{-1}}{2}}{\dfrac{1}{2}}=\left(2\cdot2+\dfrac{2}{2}\right)\cdot2=10$
答案（D）：
$\dfrac{2\left(\dfrac{1}{2}\right)^{-1}+\dfrac{\left(\dfrac{1}{2}\right)^{-1}}{2}}{\dfrac{1}{2}}=\left(2\cdot2+\dfrac{2}{2}\right)\cdot2=10$
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