23.已知有理數(shù)a,b,c在數(shù)軸上所對(duì)應(yīng)的點(diǎn)分別是A,B,C三點(diǎn),且a,b,c滿足,①多項(xiàng)式
|a|+(a-2)x+7關(guān)于x的二次三項(xiàng)式;②(b-1)
2+|c-5|=0.
(1)求a,b,c的值;
(2)點(diǎn)P為數(shù)軸上C點(diǎn)右側(cè)一點(diǎn),且點(diǎn)P對(duì)應(yīng)的數(shù)為y,化簡(jiǎn)|y+2|+2|1-y|-|y-5|.
(3)點(diǎn)A在數(shù)軸上以每秒1個(gè)單位長(zhǎng)度的速度向左運(yùn)動(dòng),同時(shí)點(diǎn)B和點(diǎn)C在數(shù)軸上分別以每秒m個(gè)單位長(zhǎng)度和4個(gè)單位長(zhǎng)度的速度向右運(yùn)動(dòng)(其中m<4),若在整個(gè)運(yùn)動(dòng)的過(guò)程中,點(diǎn)B到點(diǎn)A的距離與點(diǎn)B到點(diǎn)C的距離差始終不變,求m的值.