25.如圖A在數(shù)軸上所對(duì)應(yīng)的數(shù)為-2,點(diǎn)B在點(diǎn)A右邊距A點(diǎn)4個(gè)單位長(zhǎng)度.
(1)點(diǎn)B所對(duì)應(yīng)的數(shù)是
;
(2)若點(diǎn)A以每秒2個(gè)單位長(zhǎng)度沿?cái)?shù)軸向左運(yùn)動(dòng),同時(shí)點(diǎn)B以每秒3個(gè)單位長(zhǎng)度沿?cái)?shù)軸向右運(yùn)動(dòng),
①當(dāng)點(diǎn)A運(yùn)動(dòng)到-6所在的點(diǎn)處時(shí),點(diǎn)B所對(duì)應(yīng)的數(shù)為
;此時(shí)A,B兩點(diǎn)間距離為
;
②當(dāng)A,B運(yùn)動(dòng)到①所在的位置時(shí),點(diǎn)A立即改變方向向右運(yùn)動(dòng),點(diǎn)B同時(shí)立即向左運(yùn)動(dòng),而保持各自原速度不變,再經(jīng)過(guò)t秒A,B兩點(diǎn)相距10個(gè)單位長(zhǎng)度:則l的值為
.