Question

下列哪个数小于它的倒数？

Which of these numbers is less than its reciprocal?

$-2$

$-1$

$0$

$1$

$2$

知识点：不等式

$0$ 没有倒数， $1$ 和 $-1$ 的倒数都是它们本身。

$2$ 的倒数是 $\frac{1}{2}$ ，但 $2$ 不小于 $\frac{1}{2}$ 。

因为 $-2 < -\frac 12$ ，所以 $-2$ 是唯一小于其倒数的选项。

所以正确答案是 A。

$0$ has no reciprocal, and $1$ and $-1$ are their own reciprocals.

The reciprocal of $2$ is $\frac{1}{2},$ but $2$ is not less than $\frac{1}{2}.$

Therefore, as $-2 < -\frac 12,$ we know that $-2$ is the only one of the answer choices that is less than its reciprocal.

Thus, A is the correct answer.