Question

如圖，數(shù)軸上兩點(diǎn)對(duì)應(yīng)的實(shí)數(shù)分別是1和，若點(diǎn)關(guān)于點(diǎn)的對(duì)稱點(diǎn)為點(diǎn)，則點(diǎn)所對(duì)應(yīng)的實(shí)數(shù)為（　　）.

A．

B．

C．

D．

Answer 1

A

設(shè)點(diǎn)C所對(duì)應(yīng)的實(shí)數(shù)是．根據(jù)中心對(duì)稱的性質(zhì)，即對(duì)稱點(diǎn)到對(duì)稱中心的距離相等，即可列方程求解．?dāng)?shù)軸上兩點(diǎn)間的距離等于數(shù)軸上表示兩個(gè)點(diǎn)的數(shù)的差的絕對(duì)值，即較大的數(shù)減去較小的數(shù)．
設(shè)點(diǎn)C所對(duì)應(yīng)的實(shí)數(shù)是．
則有
x=
故選A．