28.已知點(diǎn)A在數(shù)軸上對(duì)應(yīng)的數(shù)為a,點(diǎn)B對(duì)應(yīng)的數(shù)為b,且
與2x
ay
b+7是同類項(xiàng).
(1)則a=
,b=
;
(2)數(shù)軸上在A點(diǎn)右邊有一點(diǎn)C到A、B兩點(diǎn)的距離之和為26,若點(diǎn)C在數(shù)軸上所對(duì)應(yīng)的數(shù)為x,求x的值;
(3)若點(diǎn)A,點(diǎn)B同時(shí)沿?cái)?shù)軸向正方向運(yùn)動(dòng),點(diǎn)A運(yùn)動(dòng)的速度為2單位/秒,點(diǎn)B運(yùn)動(dòng)的速度為3單位/秒,若|AB|=5,求運(yùn)動(dòng)時(shí)間t的值.