【知識(shí)準(zhǔn)備】若數(shù)軸上A點(diǎn)對(duì)應(yīng)數(shù)x,B點(diǎn)對(duì)應(yīng)數(shù)y,M為AB中點(diǎn),則我們有中點(diǎn)公式:M對(duì)應(yīng)的數(shù)為
.
(1)在一條數(shù)軸上,O為原點(diǎn),點(diǎn)C對(duì)應(yīng)數(shù)c,點(diǎn)D對(duì)應(yīng)數(shù)d,c>2,且有|c-3+d|+(d+2)
2=0.則CD的中點(diǎn)N所對(duì)應(yīng)的數(shù)為
1.5
1.5
.
(2)【問(wèn)題探究】在(1)的條件下,若P點(diǎn)從C點(diǎn)出發(fā),以每秒1個(gè)單位的速度向左運(yùn)動(dòng),運(yùn)動(dòng)了6s后,Q點(diǎn)從D點(diǎn)出發(fā),以每秒2個(gè)單位的速度向右運(yùn)動(dòng),R為PQ的中點(diǎn).設(shè)Q點(diǎn)運(yùn)動(dòng)時(shí)間為t秒,t為何值時(shí)R到點(diǎn)C的距離為2.
(3)【拓展延伸】若數(shù)軸上A點(diǎn)對(duì)應(yīng)數(shù)x,B點(diǎn)對(duì)應(yīng)數(shù)y,M為AB靠近A的三等分點(diǎn),則我們有三等分點(diǎn)公式:M對(duì)應(yīng)的數(shù)為
.若數(shù)軸上A點(diǎn)對(duì)應(yīng)數(shù)x,B點(diǎn)對(duì)應(yīng)數(shù)y,M為AB靠近A的四等分點(diǎn),則我們有四等分點(diǎn)公式:M對(duì)應(yīng)的數(shù)為
.
①填空:若數(shù)軸上A點(diǎn)對(duì)應(yīng)數(shù)x,B點(diǎn)對(duì)應(yīng)數(shù)y,M為AB靠近A的5等分點(diǎn),則我們有5等分點(diǎn)公式:M對(duì)應(yīng)的數(shù)為
.
②在(2)的條件下,若E是PQ最靠近Q的五等分點(diǎn),F(xiàn)為PC中點(diǎn),求5OE+14OF的最小值?并求出此時(shí)t的取值范圍.