25.已知:數(shù)軸上點(diǎn)A,C對(duì)應(yīng)的數(shù)分別為a,c,且滿足|a+7|+|c-2|=0.點(diǎn)B對(duì)應(yīng)的數(shù)為-3.
(1)a=
,c=
.
(2)若在數(shù)軸上有兩動(dòng)點(diǎn)PQ分別從A,B同時(shí)出發(fā)向右運(yùn)動(dòng),點(diǎn)P的速度為2個(gè)單位長(zhǎng)度/秒,點(diǎn)Q的速度為1個(gè)單位長(zhǎng)度秒,當(dāng)點(diǎn)P在點(diǎn)D追上了點(diǎn)Q,求點(diǎn)D對(duì)應(yīng)的數(shù)為多少?
(3)若在數(shù)軸上找一個(gè)點(diǎn)M,使得點(diǎn)M到點(diǎn)A和點(diǎn)C的距離之和為17,請(qǐng)求出點(diǎn)M所對(duì)應(yīng)的數(shù)?(要求寫(xiě)詳細(xì)解答過(guò)程)