Question

10．已知：如圖，A，B，C，D四點(diǎn)對(duì)應(yīng)的實(shí)數(shù)都是整數(shù)，若點(diǎn)A對(duì)應(yīng)于實(shí)數(shù)a，點(diǎn)B對(duì)應(yīng)于實(shí)數(shù)b，點(diǎn)C對(duì)應(yīng)于實(shí)數(shù)c，數(shù)軸上每個(gè)小格對(duì)應(yīng)一個(gè)單位長(zhǎng)度且c-2b=5，那么數(shù)軸上的原點(diǎn)應(yīng)是（　�。�點(diǎn)．

• A． A點(diǎn)
• B． B點(diǎn)
• C． C點(diǎn)
• D． D點(diǎn)

Answer 1

分析 根據(jù)實(shí)數(shù)與數(shù)軸的關(guān)系得到c-b=1，c-2b=5建立方程組，解得b=-4，c=-3，即可確定原點(diǎn)．

解答 解：由數(shù)軸可得，c-b=1①，
∵c-2b=5②，
解由①②所組成的方程組得，b=-4，c=-3，
∴數(shù)軸上的原點(diǎn)應(yīng)是D點(diǎn)．
故選：D．

點(diǎn)評(píng) 本題考查了實(shí)數(shù)與數(shù)軸的關(guān)系：實(shí)數(shù)與數(shù)軸上的點(diǎn)是一一對(duì)應(yīng)的關(guān)系；原點(diǎn)左邊的點(diǎn)對(duì)應(yīng)負(fù)實(shí)數(shù)，右邊的點(diǎn)對(duì)應(yīng)正實(shí)數(shù)；離原點(diǎn)越遠(yuǎn)，其點(diǎn)對(duì)應(yīng)的實(shí)數(shù)的絕對(duì)值越大．